Producer s Update and Research Highlights

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1 2011 Producer s Update and Research Highlights

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3 Friends of the Animal Sciences Department and the College of Agriculture and Life Sciences, Welcome to Cattlemen s College. Our Producer s Update booklet contains summaries of today s presentations and brief reviews of research projects being conducted by members of the Animal Sciences Department and College of Agriculture and Life Sciences. You will find contact information for our faculty in the back of the book, so feel free to get in touch with any of our members. We re proud to be partners in supporting animal agriculture in Arizona through our teaching, research and extension programs. Our educational programs are designed to enhance the career development of our students through classroom experiences, extracurricular activities and employment opportunities. It is important to note as you glance through the articles in this booklet that our undergraduate and graduate students are directly involved in the process of generating new knowledge. The discipline, hard work and critical thinking skills that go into a research project provide experiences that cannot be duplicated in the classroom. We believe these experiences add value to our students educational experience here at the University of Arizona. A recent trend in research is integration of fundamental research, applied research and technology implementation. In medicine, the catch phrase is from the bench (lab bench) to the bedside. Of course, this is not a new concept in our College of Agriculture and Department of Animal Sciences; we ve been doing this for over 100 years. Therefore, you will note that some of the reports in the update may have more immediate applications than others, while some research is designed to generate the fundamental understanding of animal science needed to address future problems. The reports are a sampling of work going on at the UA. This has been a year of transitions, with more to come in the year ahead. We have had several faculty members depart to take positions at other universities, and we have had several retirements. We are grateful to be able to replace most of these faculty members, given the tough economic times. With respect to retirements, we want to thank Dean Eugene Sander and Associate Deans Jim Christensen and Dave Cox for their years of service. We are also thankful for Dean Colin Kaltenbach s continued service into the fall of this year during the transition as a new dean and leadership team come aboard. A critical retirement in our department this past year was that of Dr. Bob Kattnig. Bob served our department and the cattle industry in Arizona for twenty years, and he was instrumental in establishing several important programs that serve producers in the state, including the ALIRT and BQA programs. We want to recognize and thank Dr. Kattnig. Unfortunately, we also lost a friend and colleague with the passing of Dr. Roy Ax. Dr. Ax served as department head for over ten years and as a teacher, advisor and friend to many Arizona students for his 20-plus years at the University. We are grateful for his dedication to our students, the Department and the livestock industry. These are just a few of the things going on the Animal Sciences Department. We re always happy to fill in the details; just come by for a visit or give us a call. Sincerely, Ron Allen, Head and Roy and Phyllis Hislop Chair Department of Animal Sciences University of Arizona Special thanks to Debbie Reed for compiling and editing this edition of the Producer s Update and Research Highlights.

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5 Schedule Cattlemen s College Range Cattle Nutrition: From the Lab to Your Ranch Arizona Cattlemen s Association Convention July 28, 2011 Prescott, Arizona Presented by the University of Arizona Department of Animal Sciences 12:00 How Animals Select Their Diets Beth Burritt, Area Rangeland Extension Agent, Department of Wildland Resources, Utah State University 12:45 You are What Your Mother Eats; Does This Apply to Your Cows? Dr. Nathan Long, Assistant Professor, Department of Animal Sciences, University of Arizona 1:20 Maternal Stress Causes Fetal Metabolic Adaptations that Lower Postnatal Performance Dr. Sean Limesand, Associate Professor, Department of Animal Sciences, University of Arizona 1:55 Selecting Your Sires to Match Your Environment and Cow Herd Dr. David Schafer, Resident Director, V-V Ranch, University of Arizona 2:20 Final Questions 2:30 Adjourn

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7 Table of Contents Cattlemen s College Proceedings What Makes an Animal Choose a Forage? 11 Beth Burritt Understanding and Using Livestock Behavior 17 Beth Burritt You are What Your Mother Eats; Does This Apply to Your Cows? 27 Nathan M. Long Maternal Stress Causes Fetal Metabolic Adaptations that Lower Postnatal Performance 29 Sean W. Limesand Sire Selection For Your Environment and Cow Herd 31 David W. Schafer Producer s Update and Research Highlights Change on the Range: Ten Years of Rangeland Monitoring on the Tonto National Forest 37 Jim E. Sprinkle, George Ruyle and Michael Crimmins Effects of a Long Acting Trace Mineral Rumen Bolus Upon Range Cow Productivity 38 Jim E. Sprinkle, David W. Schafer, S. Peder Cuneo, Doug Tolleson and R. Mark Enns Collegiate Cattle Growers Association 45 Dan Kiesling Livestock Judging Team 47 Dan Kiesling Characterization of Uterine ph During the Estrous Cycle of the Mare 48 Leah V Penrod, Stacie E Deaver, Erin K Prendergast, Glenn C Duff, Michelle L Rhoads and Mark J Arns Effects of Oxytocin, LPS, and Polyunsaturated Fatty Acids on PGF2α Secretion and Gene Expression during Equine Endometrial Culture 51 Leah V Penrod, Ronald E Allen, Michelle L Rhoads, Jason L Turner, Sean W Limesand and Mark J Arns Oxytocin Stimulated Release of PGF2α and its Inhibition by Indomethacin and Atosiban During Culture of Equine Endometrial Explants 54 Leah V Penrod, Michelle L Rhoads, Sean W Limesand and Mark J Arns

8 Elevated Catecholamines are the Predominant Inhibitors of Insulin Secretion and Contribute to Altered Metabolic Phenotype During Acute Hypoxemia in Fetal Sheep 57 Dustin T Yates, Abigail L Fowden, Anthony R Macko, Xiaochaun Chen, Alice S Green and Sean W Limesand Honors College Research Grant Project 58 Sarah Klopatek Comparison of Feedlot Performance and Carcass Merit of Various Crossbred Cattle 59 Samuel R Garcia1, John A Marchello1, Hamdi A Ahmad1 and Russell Tronstad Elevated Catecholamines are the Predominant Inhibitors of Insulin Dry and Wet Aging Effects on Tenderness, Palatability and Oxidative Rancidity in Beef Steaks 65 Tiffany J Hebb Faculty Bios and Research Interests Department of Animal Sciences Faculty List and Contact Information 79

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11 What Makes an Animal Choose a Forage? Beth Burritt Utah State University, Department of Wildland Resources Logan, Utah Department of Animal Sciences, The University of Arizona INTRODUCTION Have you ever considered why animals behave as they do and what it means for management? Why livestock moved from pastures or rangelands to confinement or vice versa often get sick, perform poorly and refuse to eat even when fed nutritious foods? Why animals moved to new, unfamiliar environments frequently suffer more from predation, malnutrition, and overeating poisonous plants? Why some animals know exactly which poisonous plants to avoid while others don t have a clue? Why livestock on pastures and rangelands perform better when they have a wide variety of plants than when they only have a few plant species to eat? Simple strategies that use knowledge of behavior can improve the efficiency and profitability of agriculture, the quality of life for managers and their animals, and the integrity of the land. Which foods animals eat and where they forage influences weight gains, reproduction, and carrying capacity of pastures and rangelands. What factors drive food and habitat selection? Animals are thought to prefer foods that are palatable, but what is palatability. Is it merely a matter of taste? WHAT IS PALATABILITY? Palatability is considered to be a matter of taste. Yet, if palatability is merely a matter of taste, why do herbivores supplemented with polyethylene glycol increase their intake of unpalatable plants high in tannins? Why would goats eat woodrat houses? Why would cows prefer to eat moldy hay and endophyte-infected grass high in alkaloids rather than nutritious pasture legumes? Flavor-Feedback Interactions. Palatability is much more than a matter of taste. Palatability is the relationship between a food s flavor and its nutrient and toxin content. When an animal eats a food, it is digested releasing nutrients and in many cases toxins, because all plants contain some level of toxins. These nutrients and toxins are absorbed in the gut and travel to the cells and organs of the body. Signals are then sent back to the brain to tell it how well a food meets the animal s nutritional needs. The brain then pairs the food s flavor with its nutritional benefits and/or toxicity. The brain stores this information for future use. Scientists refer to this process as postingestive feedback (Provenza 1995). Feedback is positive (increases palatability) if a food meets nutritional needs. Feedback is nega-tive (decreases palatability) if a food is low in nutrients, has too many rapidly digestible nutrients (like grain), or contains high levels of toxins. Palatability is influenced by the nutrient and toxin content of the food, the nutritional needs of the animal, and the animal s past experience with the food. The senses (smell, taste, sight) enable animals to discriminate among foods and provide pleasant or unpleasant feelings associated with eating. Whether or not an animal eats a food is not determined by flavor alone, rather is determined by the experiences associated with eating the food. Changes in palatability through flavor-feedback interactions occur automatically. Animals don t need to think about or remember the feedback event. Even when animals are anesthetized, postingestive feedback still changes Producer s Update and Research Highlights

12 palatability. When sheep eat a new food and then receive a toxin during deep anesthesia, they become averse to the food because the negative feedback of the toxin happens even when the animals are deeply asleep. Thus, feedback occurs automatically. At times, changes in palatability may not be rational. For example, people acquire food aversions even when they know their illness was not caused by the food. People often acquire strong aversions to foods eaten just before becoming nauseated even if they know the flu, carsickness, or seasickness - not the food - was responsible for the nausea. Polyethylene Glycol. Many woody plants contain tannins. Tannins reduce the digestibility of protein and energy in foods, and some are toxic. Polyethylene glycol binds (PEG) with tannins, preventing their adverse effects. Animals fed small amounts of PEG eat much more of foods high in tannins because the tannins no longer produce negative effects. Thus, it is the aversive post-ingestive effects of tannins, not their flavor that renders plants high in tannins unpalatable. Once PEG binds tannins, the positive post-ingestive effects of nutrients in the food make high-tannin foods palatable. That s why PEG can enable animals to eat unpalatable plants, such as serecia or oak brush, that are high in tannins. Goats and Woodrat Houses. The shrub blackbrush is deficient in energy and protein. Several years ago during a winter-grazing study, we placed small groups of goats on six blackbrush pastures. As the study progressed, goats became increasingly averse to blackbrush. In one pasture they began to eat woodrat houses. Goats acquired a preference for woodrat houses because the houses contained urine-soaked (nitrogen-rich) vegetation that helped goats rectify their deficiency in protein. By the end of the study, goats that ate woodrat houses lost 12% of body weight, whereas goats that didn t eat woodrat houses lost 20%. Animals deficient in nutrients seek out new foods, and they are likely to form a preference for a food, no matter how odd, if the food corrects a nutritional deficit or imbalance. Cows and Legumes. Animals form preferences for foods high in nutrients but diets too high in nutrients or diets that are not nutritionally balanced can cause ruminants to limit intake and search for other foods. When it comes to nutrients, herbivores can get too much of a good thing. High quality pasture may provide cattle with a diet too high in protein relative to energy, which results in ammonia toxicity. The dietary imbalance probably caused cows grazing a pasture high in legumes to seek moldly hay and mature endophyte-infected grass. When strips of grass were planted in the pasture, cattle performance increased and their strange feeding behaviors stopped. IF THAT S ALL THERE IS TO PALATABILITY... So, palatability is the interrelationship between flavor, feedback, and nutritional state. But if that s all there is to palatability, then why do dairy cows reared in confinement perform poorly on pasture and livestock reared on rangelands may perform poorly in drylot or feedlot? In both cases, animals have nutritious food available free choice, but food intake is low, performance is poor, and animals are more likely to suffer diseases. Likewise, why do cows of the same age and breeding differ in performance when eating ammoniated straw? Livestock Culture. Pasture and rangeland researchers and managers typically consider foraging only in terms of how the physical and chemical characteristics of plants influence an animal s intake rate. The social environment is rarely considered important when studying diet and habitat selection. This is unfortunate because a young animal s interactions with their mother and peers have a lifelong influence on where it goes and what it eats. When it comes to managing pastures and rangelands that contain a variety of foods and terrain, it is critically important to understand how social factors influence the foods eaten by livestock and foraging locations, both of which affect animal performance and carrying capacity. 12 Producer s Update and Research Highlights

13 The impact of social learning on adaptation helps account for why herbivores of the same species can live in very different environments and survive on radically different foods. A calf reared in shrub-dominated deserts of southern Utah is different from a calf reared on grass in the marshes of Louisiana. A bison reared on shrub-dominated ranges in Alaska is different from a bison reared on grasslands in Montana. We typically consider cattle, elk, and bison to be grazers and goats, deer, antelope, and sheep to be forb eaters and browsers. However, grazers can live nicely on diets of shrubs, and browsers can survive primarily on grass if they learn to do so. Mom teaches her young about her environment from the location of water and cover, to dangers such as predators, to the kinds and locations of nutritious and toxic foods. Learning about foods from mom begins early in life as flavors of foods mom eats are transferred to her offspring in utero and in her milk. As offspring begin to forage, they learn what to eat and where to go by following mother. Young animals learn quickly to eat foods mother eats, and they remember those foods for years. Lambs fed nutritious foods like wheat with their mothers for 1 hour per day for 5 days eat more wheat than lambs exposed to wheat without their mothers. Even 3 years later, with no additional exposure to wheat, intake of wheat is nearly 10 times higher if lambs are exposed to wheat with their mothers than if lambs are exposed alone. Lambs exposed with their mothers to various foods - grains like barley, forbs like alfalfa, shrubs like serviceberry - eat considerably more of these foods than lambs exposed to these foods without their mothers. Mother also reduces her offspring s risk of eating toxic foods. If a mother avoids toxic foods and selects nutritious ones, offspring acquire preferences for foods mom eats and avoids foods mom avoids. Lambs given a choice of palatable shrubs such as mountain mahogany or serviceberry - one of which their mother was trained to avoid - show a preference for the shrub they ate with mother. Through her actions, mother models appropriate foraging behaviors for her offspring. Dairy and Beef Cows. To reduce the high cost of feeding lactating dairy cows in confinement, many producers use intensively managed pastures as a source of high-quality forage. Unfortunately, for a dairy cow raised in confinement, the barn is habitat, a total-mixed ration is food, and water comes in a trough. Thus, mature dairy cattle reared in confinement are at a disadvantage when put on pastures and expected to harvest forages they have never seen. Although they may be quite hungry, they lack the knowledge and the skills to eat pasture. Little wonder they stand at the gate and bellow to be fed - grass isn t food and the pasture isn t home. Conversely, for a beef cow reared on rangelands, riparian areas and uplands are habitat, grasses, forbs, and shrubs are food, and water comes in streams and ponds. When these animals are moved to feedlots, total-mixed rations aren t food and feedlot pens aren t habitat. The fear and stress of new foods and environments can cause huge decreases in intake and milk production. To ease these losses, dairy cows should be exposed to green chop in the barn before grazing the first time. The time cows spend on pasture should be increased gradually to reduce stress and losses in production. Exposing calves to pastures where they will be expected to forage later in life will help them be more productive as adults by increasing their preferences for pasture species and enabling them to acquire needed foraging skills. Likewise, before leaving home, cattle on their way to the feedlot should be exposed to the foods they will be expected to eat in the feedlot. Ammoniated Straw. During a 3-year study, 32 cows - 5 to 8 years of age - were fed ammoniated straw from December to May to reduce winter feed costs. Some cows performed poorly, while others maintained themselves. Researchers were baffled until they examined the dietary histories of the animals. Half of the cows were exposed to ammoniated straw with their mothers during their first 3 months of life, while the other half had never seen straw. Throughout the study, the experienced cows had higher body weight and condition, produced more milk, and bred back sooner than cows with no exposure to straw, even though they had not seen straw for 5 years prior to the study. Producer s Update and Research Highlights

14 Producers should incorporate unfamiliar low-quality foods such as ammoniated straw into their winter-feeding program cautiously. Low-quality forages should make up only a small portion of the winter forage and be increased gradually. Replacement heifers should be exposed to low-quality forages with their mothers early in life to increase intake of these foods later in life. IF THAT S ALL THERE IS TO PALATABILITY... So, palatability is the interrelationship between flavor, feedback, and nutritional state and is influenced by an animal s past experiences with food. But if that s all there is to palatability, then why do animals perform better when offered choices of different foods and why is the grass always greener on the other side of the fence? For example, why do sheep prefer to eat clover in the morning and grass in the afternoon, even though clover is more digestible and higher in protein than grass? Why do cattle perform better when offered individual ingredients from a total mixed ration than when fed a total mixed ration formulated to meet their needs? Why do cattle on a ranch in Montana eat plants like snowberry and sagebrush that cattle don t normally eat? Each Critter is Different. With the advent of statistics in the 20th century, great emphasis has been placed on assessing the response of the average animal to a treatment. While statistics has advanced our ability to conduct experiments, it also has made variation among individuals an enemy to counter. Nutritionists determine needs and formulate diets for the average member of the herd, not for individuals. Yet, variation is common in the need for nutrients and ability to cope with toxins, even among closely related animals. Differences among individuals in food intake and preference depend on how animals are built physically, their body s chemistry, and past experiences with different foods. When we force livestock to eat a ration to meet the needs of the average animal, or pastures that planted with a single plant, we may only meet the nutritional needs of some of the individuals in a herd. Individuals can better meet their needs for nutrients and regulate their intake of toxins when offered a variety of foods that differ in nutrients and toxins than when constrained to a single food, even if the food is nutritionally balanced. Variety allows individuals to uniquely balance their own diet. Variety is the Spice of Life. Variety is the spice of life for herbivores. Like us, they may get tired of eating the same food(s) and prefer to eat a variety of foods. Preference for particular foods declines as foods are eaten. When sheep and cattle eat a food in one flavor, such as maple- or coconut-flavored grain or straw, they prefer food with the alternate flavor on the following day. Preference also drops if animals eats too much of a food on a particular day, just as our preference for turkey declines right after eating a Thanksgiving Day meal. That s why we cook foods in different ways using a variety of herbs, spices and ingedients: How many ways can you cook ground beef? Interactions between the senses and the body help to explain why palatability changes within meals and from meal to meal. Satiety refers to the decrease in preference for the flavor of a food during eating because of interactions between a food s flavor and postingestive feedback from nutrients and toxins. Flavor receptors respond to taste (sweet, salt, sour, bitter), smell (a diversity of odors), and touch. Flavor receptors interact with receptors in the body that respond to nutrients and toxins, concentration of salts, and gut distension. Preference for the flavor of a food declines automatically as that food is eaten because of interactions between the senses and the body. These interactions cause temporary decreases in the preference for foods just eaten. This decrease in preference is more persistent when a food has either too many or too few nutrients. Aversions may be pronounced when foods contain excess toxins or rapidly digestible nutrients, such as some forms of protein and energy. Aversions also occur when foods are deficient in nutrients. They even occur when animals eat nutritionally 14 Producer s Update and Research Highlights

15 adequate foods, particularly if those foods are eaten too often or in too great an amount. Thus, eating any food to satiety causes a temporary aversion to the flavor of that food. When forced to eat the same food too frequently or excessively, people typically remark, I m sick of it. Through their actions, livestock echo the similar sentiments. Sheep and Clover. Sheep on a grass-clover pasture eat clover in the morning and switch to grass in the afternoon. Why? In the morning, hungry sheep initially prefer clover because it is highly digestible compared with grass. As they continue to eat clover, however, sheep satiate - acquire a mild aversion - from the effects of nutrients like soluble carbohydrates and proteins, from the effects of toxic cyanide compounds, and from eating the same flavor. The mild aversion causes them to switch to grass in the afternoon. During the afternoon and evening, the sheep recuperate from eating clover, and the aversion subsides. By morning, they are ready for more clover. The combination of clover and grass likely enables sheep to eat more each day than if only one species were available. Sowing clover and grass in separated strips can further enhance intake and performance compared to clover-grass mixtures. When grass and clover are planted in strips, as opposed to conventional mixtures, dry matter intake of sheep increases by 25% and milk production of dairy cows increases by 11%. The choice allows each animal to balance the mix of grass and clover, and the strip evidently minimizes time spent searching for the desired amounts of the different forages. Choice at the Bunks. Cattle fed barley, corn, alfalfa, and corn silage were compared with animals fed a nutritionally balance ration of those ingredients. Cost per pound of gain were 20% less for animals offered a choice than for those fed the mixed-ration because animals offered a choice ate less, and they ate less grain. Apparently, animals met their needs for energy and protein more efficiently when offered a choice among foods than when fed a mixed-ration, even when the ration was nutritionally balanced. Allowing individuals to choose their own diet may be less stressful for animals thereby reducing illness and improving performance. Montana Cows. Ray Banister manages 7,200 acres of rangeland in eastern Montana. His management style has evolved over 40 years from rotational grazing that involved relatively short periods of grazing and rest to boom-bust management that consists of intensive periods of grazing followed by two growing seasons of rest. Ray s boom-bust grazing management stresses systems with intensive grazing pressure, then allows them to recover. Ray believes that stress, and recovery from stress, strengthens systems. The change to boom-bust grazing challenged the Hereford cattle on Ray s ranch. Cattle could no longer eat only the most palatable plants as they had under rotational grazing. Instead, they were forced to eat all of the plants. Under the new management procedures, Ray monitors the least palatable plant species - shrubs like sagebrush and snowberry and various weeds - as indicators of when to move cattle to a new pasture. Cattle are allowed to move only after adequate use of unpalatable species. Thus, Ray reduces the competitive advantage unpalatable plants have over palatable species because grazed plants are at a disadvantage for water and nutrients when competing with ungrazed plants. Under boom-bust management, cattle now eat snowberry and sagebrush as soon as they enter a new pasture. The cows evidently have learned how to mix their diets in ways that better enable them to eat all plant species. Cattle likely lessen the aversive effects of toxins by eating palatable plants high in nutrients along with unpalatable species high in toxins. The better the nutrient status of the animal, the better it is able to detoxify toxic compounds found in all plants. It took Ray s cows 3 years to adapt to the boom-bust style of management. During that time, the weaning weights of calves plunged from well over 500 pounds to 350 pounds then rebounded back to over 500 pounds. Once the older Producer s Update and Research Highlights

16 cows made the transition, their calves learned from their mothers how to thrive under boom-bust management. The calves that Ray keeps as replacements never have to make the harsh transition because they were trained by their mothers that all plants are food at Ray s place. Ray has increased the carrying capacity of his ranch, and made his operation less subject to the adverse effects of drought. Occasional disturbance, followed by rest, creates a diversity of micro and macro habitats for all plants, and that reduces the number of invasive plants. It is hard to find any part of the ranch - riparian areas or uplands - that lacks abundant plant cover, and that creates a forage bank during drought. The abundance and diversity of plants also lessens soil erosion, which leads to clean water and great habitat for fish, waterfowl, and upland wildlife. CONCLUSION Scientists and managers often ignore the power of behavior to transform systems, despite compelling evidence. We know that the environment acting on biological steps is as important in shaping creatures as their genetic code. For those willing to understand how environment interacts with genes to influence behavior, the potential is virtually unlimited. Once mastered, behavioral principles and processes become a part of the infrastructure of the person, so they are readily transferred from one situation and locale to another. People who understand and use behavioral principles in management can enhance the welfare of animals and the integrity of land. For more information: extension.usu.edu/behave or contact Beth Burritt at beth.burritt@usu.edu or phone (435) Producer s Update and Research Highlights

17 Understanding and Using Livestock Behavior Beth Burritt Utah State University, Department of Wildland Resources Logan, Utah Department of Animal Sciences, The University of Arizona Anyone who raises livestock, especially on rangelands, knows the interactions between weather, soils, plants, animals, and people are extremely complex. Not surprisingly, the behavior of animals is also complex but understanding what motivates livestock can help you manage your livestock more effectively. The examples presented in this handout demonstrate how understanding behavior can: 1) help you change the behavior of your livestock; 2) use animal learning to your advantage; or 3) anticipate problems with livestock due to management decisions. Training Livestock to Eat the Best and Leave the Rest Typically, livestock are removed from pastures when key plant species are grazed to a specified height. This management practice may have unintentionally trained our livestock, especially cattle, to eat the best plants and leave the rest by not encouraging them to increase the number of different plants they eat. High stock density, timing of grazing, supplements, and positive experiences can increase intake of so called unpalatable plants, improve biodiversity, and cut feed costs. 1. Changing Palatability: Eating Sagebrush Grazing sagebrush in the fall and winter reduces its abundance, improves biodiversity and wildlife habitat. So what s the best way to get livestock to eat sagebrush? Supplement them! In this case, we re using the idea of using nutrients to increase intake of plants with toxins. Research shows sheep eat more sagebrush despite its high terpene content when they re supplemented with protein and energy. Supplements help livestock detoxify terpenes in sagebrush and eliminate them from the body. One study found grazing reduced dense stands of sagebrush by 66% while increasing the amount of grass 43%, forbs 60%, and other shrubs 14%. Livestock can learn to mix their diets with plants low and high in nutrients and toxins without reducing performance. Below are three examples of using supplements to help livestock eat sagebrush. a. Eating sagebrush to save it: Creating and improving resilience Chuck Petersen is teaching cows to eat sagebrush to improve the land. If effective, this approach to habitat renovation will be an alternative to chemicals, mechanical treatments, and fire. Chuck is conducting his project on Agee Smith s Cottonwood Ranch near Wells, NV. Pastures are a mix of Wyoming and basin big sagebrush with an understory of grasses and forbs. Each fall as cattle are turned onto the pastures, they are supplemented with meadow hay and pellets high in protein and energy to help cattle detoxify terpenes in sagebrush. When cattle first go onto the pastures, they eat the understory and leave the sagebrush. By the end of the adaptation phase (10 days to two weeks), they re eating sagebrush and are moved to new pastures that contain sagebrush. When cattle enter the new pastures, they mix sagebrush with the understory. The change in behavior maybe due to experience alone but some studies suggest that rumen microbes need time to adapt to the terpenes in sagebrush. Fall grazing increased grasses and forbs in the understory during the next growing season, encouraged new sagebrush Producer s Update and Research Highlights

18 seedlings and caused the death of old, nonproductive sagebrush plants. Calves tended to gain weight while on sagebrush pastures and smaller framed cows generally maintained their weight or gained, larger framed cattle tended to lose weight. Chuck and Agee are hoping to change the culture of the cattle on the ranch by getting them to include sagebrush as part of their diet to reduce hay costs in fall and winter and improve biodiversity on rangelands. b. Rancher Saves Money by Teaching His Cows to Eat Sagebrush Mat Carter, an Oregon rancher, taught his cattle to use sagebrush as winter feed and as a way to grow more grass for his cows. The first winter, he corralled 150 cow-calf pairs with electric fence on 5 to10 acres for 3 days and fed them 15 to 20 lbs/hd/d of meadow hay. His pastures were a mix of low and big sagebrush, gray and green rabbitbrush, and bitterbrush with an understory of grasses. Grazing decreased the amount of brush and increased grasses and new shrub seedlings. The following winter, snow cover was light so Mat fed 3 to 10 lbs/hd/d of meadow hay to 400 pregnant cows and moved them about every 3 days. The amount of hay fed depended on weather and available forage. Matt noted that as he turned his cattle onto a new strip of pasture some ate grass, others bitterbrush and others sagebrush. In , he grazed rangeland where the canopy cover of big sagebrush was 50 to 70%. Some of the shrubs stood 4 to 6 feet tall. Snow was deep that year, 2 to 4 feet. For nearly a month cattle were fed 10 to 15 lbs/hd/d of hay. The rest of their diet was sagebrush. In 2008, he leased some cattle and trained them to eat sagebrush. Snow was deep so only sagebrush was available. He started feeding 20 lbs of hay and over a 2-week period he reduced hay to 6 lbs/hd/d. Cattle were in good body condition when they came to the ranch and remained in good condition throughout the winter. Besides saving on hay and increasing the amount of grasses and forbs on his rangeland, Matt has noted several other benefits to using sagebrush as winter forage. His cattle eat sagebrush even when other forage is available. They also started eating plants Mat had never seen them eat before like stinging nettle, whitetop, lupine and various wild flowers. Finally, when cattle graze sagebrush rather than hay alone, they require less water. One important point is Mat calves in June. In the middle of winter his cows have fairly low nutrient requirements. Browsing sagebrush has no adverse effect on his calf crop and his cattle breed back just fine. He s found no downside to his cattle to eating sagebrush. c. Grazing to improve wildlife habitat In a demonstration project, 2200 sheep were supplemented to heavily browse sagebrush in fall and early winter. Sheep were supplemented daily with a mix alfalfa, beet pulp, corn and soybean meal. According to one sheep producer working on the project, his replacement ewes continued to eat sagebrush even without supplement. After fall grazing that following spring, sagebrush cover decreased from 27% to 9% in grazed plots while sagebrush in the ungrazed plots remained unchanged. Forb and grass cover were slightly higher in grazed versus ungrazed plots and increased more the following year. Forbs and grasses are vitality important for sage-grouse and their chicks. Grouse used grazed areas more than areas not grazed by sheep. Biologists can track use of an area by counting bird pellets. Grazed plots contained five times as many pellets as ungrazed plots. Also, three times as many grouse were flushed from grazed plots as ungrazed plots. There was good news for the producer too. The project is increasing available forage for sheep. Supplementing ewes 18 Producer s Update and Research Highlights

19 to eat sagebrush also flushed ewes to improve lambing. Sheep used in the study maintained their body condition while browsing sagebrush. d. How can you use this idea? Unfortunately, increasing use of sagebrush can be difficult. How effective supplements are in changing palatability of sagebrush depends on the experience of the animal, the terpene and nutrient content of the sagebrush, and what s growing in the understory. The examples above have several things in common: 1) high stock densities; 2) animals were moved often; 3) animals browsed sagebrush in fall or winter when terpene levels are low and forbs and grasses are dormant; 4) supplemental feed helped animals eat and detoxify sagebrush; 5) animals were not starved into eating sagebrush; and 6) animals maintained body condition while eating sagebrush. 2. Changing Palatability: Eating Weeds Why don t livestock eat weeds? Many weeds contain toxins but as long as livestock have a variety of plants to eat, the majority of weeds are not toxic enough to cause health problems or death. Novelty may be a better answer because when weeds invade a pasture, they are likely a novel food to livestock grazing the pasture. Since the animals already have a preferred diet of familiar foods, they simply won t eat the new food. In no time, weeds take over because ungrazed plants have a competitive advantage over grazed plants. How do we get livestock to change their minds about weeds? Teach them. a. The steps to training 1) Know your weed. Make sure your plant is not high in toxins and likely cause health problems or death. Check out your weed s nutritional value. Most weeds are nutritious. The more nutritious the weed, the more likely your animals will learn to eat the weed and keep eating it. 2) Train young females because young animals are more likely to try new foods and they will teach their offspring to eat the weed. 3) Decrease the fear of eating new foods by giving your animals small amounts of a variety of nutritious, new foods in familiar feeders. 4) Reduce food novelty by mixing weeds with familiar foods for a day or two. You can also use a flavor like molasses provided your animals are familiar with molasses. If you simply spray molasses on the weed, there s a good chance your cows won t eat the weed. It s the training process that works not the molasses!! 5) Use competition to your advantage. A group of animals will encourage each other to eat both the new foods and weed. They don t want to miss out on a good food. 6) If the weed is hard to eat because it s prickly or thorny, give your animals time to learn how to eat it by putting them in a small pasture with the target weed and a variety of other plants b. How can you use this idea? The method for training cows to eat weeds is much more straightforward than getting livestock to eat sagebrush. It was developed by Kathy Voth and based on research from the BEHAVE Project at Utah State University. The steps are briefly listed above. For more information on training your animals to eat weeds, visit Kathy s website or order her book Cows Eat Weeds at Livestock Learn to Use Medicines Why do livestock eat soil or chew bones? Are they just bored or are they lacking some nutrient in their diet? Many researchers don t believe that livestock select foods to meet mineral requirements because research has shown that animals don t instinctively recognize specific minerals. However, livestock can learn to prefer foods that rectify nutritional imbalances including mineral deficiencies. They can also learn to prefer medicines that alleviate illness. Below are several research examples of how livestock learn to remedy nutritional imbalances and illnesses. Producer s Update and Research Highlights

20 1. Calcium and Phosphorus Lambs fed diets either too high or adequate in phosphorus learn to avoid a flavor paired with phosphorus. Conversely, when they were deficient in phosphorus, they learn to prefer a flavor paired with phosphorus. In another study, lambs deficient in calcium had a higher preference for foods that contained calcium carbonate than lambs adequate in calcium. Lambs deficient in phosphorus had a higher preference for foods that contained sodium phosphate compared with lambs adequate in phosphorus. The results suggest animals can self-regulate intake of these minerals and may explain why animals deficient in minerals eat foods they normally wouldn t eat. 2. Bloat Bloat is a big problem for producers. Lambs form strong aversions to foods associated bloat. They also formed strong preferences for foods that cause relief from bloat. Now that we know animals can learn about foods based on the effects of bloat, the next step is to translate this to the field. Soon we may know if animals can learn to mix birdsfoot trefoil (which contains tannins) with their alfalfa (which contains saponins) to prevent bloat. Tannins are believed to interact with saponins to prevent bloat. 3. Reducing Parasites Tannins are secondary compounds produced by plants. At high doses, they reduce intake and protein digestibility but at lower doses they benefit ruminants by reducing internal parasites. Most shrubs contain tannins as well as sudangrass, birdsfoot and big trefoil, sorghum, sulla, sainfoin, and sericea lespedeza. Studies show lambs infested with parasites had higher preferences for foods containing tannins, and ate more of a tannin-containing food than lambs with low levels of parasites. Consuming high-tannin foods also reduced fecal egg counts - a measure of parasite infestation. There was a direct relationship between the amount of tannin eaten and the decline in fecal egg counts. However, intake and preference for tannin food were not different between groups when parasites levels were similar. These studies suggest: 1) lambs can detect internal parasite infestations, 2) they can learn about the relationship between the flavor of tannin and relief from internal parasites and 3) tannins can reduce parasite levels. 4. Relieving Heartburn Sodium bicarbonate helps relieve grain acidosis. Lambs prefer foods that contain sodium bicarbonate after eating large quantity of grains. They also drank more water containing sodium bicarbonate when they were on high versus low-grain diets. 5. Choosing the Right Medicine Juan Villalba and Ryan Shaw conducted a difficult study where sheep were familiar with three diets: 1) high grain, 2) high tannin and 3) high oxalate; and three medicines 1) PEG 2) bentonite, and 3) dicalcium phosphate. One group was fed the diets and medicines at different times of the day (control). The other group received the correct medicine right after eating a diet that caused illness (treatment). Bentonite alleviates grain acidosis, PEG for tannin, and dical for oxalate. Animals were then put in one of the above physiological states (grain acidosis, too much tannin, too much oxalate) and then offered a choice of three medicines. Control animals ate the same proportion of medicines regardless of which diet they ate. The medicine preferred by the treatment group depended on their physiological state. Sheep with training chose the correct medicine; meaning sheep can learn to use medicines. 6. How to Use This Information Animals do not eat substances to prevent deficiencies. When they suffer a deficiency or illness, they seek out novel 20 Producer s Update and Research Highlights

21 substances to eat. If they eat a substance that rectifies the problem, animals form a preference for it. If your animals are eating soil, bones, or other odd substances, it is likely they have a deficiency or illness. Minerals: I m often asked about free-choice mineral systems. My recommendation is to offer trace mineral salt mixtures or blocks along with free-choice minerals that are known to be deficient in your area. Bloat: Bloat blocks work because they are high in nutrients and contain compounds to counteract bloat. With bloating legumes planting another forage that contains tannin in the pasture may alleviate problems with bloat. High grain diets: Livestock on high grain diets should be offered sodium bicarbonate or bentonite to alleviate acidosis and keep intake high. Parasites: Offering variety, which is normally not a problem on rangeland, gives animals a variety of plants to eat to rectify problems. Rangeland plants, especially woody plants, contain a variety of secondary compounds that may reduce parasite loads or counteract toxins in other plants. In dry climates livestock rarely have high infestations of parasites, you may want to send in a fecal analysis to check your animal s parasite load. If it s low, regularly worming livestock may be a waste of money. Habitat Preference Below are a several examples of how experience affects habitat selection. They profile: 1) how strongly animals prefer their home range; 2) point out that you re changing more than location when moving animals to uplands; 3) discuss the possible downside to buying replacement heifers; and 4) the dangers of moving livestock to new locations. 1. Home, Home on the Range In the 1960s, white-tailed deer were a problem in the Adirondacks. They are especially fond sugar maple, yellow birch, and other commercially valuable species. Deer browsing inhibits growth of trees seedlings and competes with people who depended on harvesting and growing timber for a living. The plan was to reduce the deer population by 50% to allow maple and birch seedlings to regrow but biologists disagreed on how to achieve that goal. A young biologist proposed a solution. Hunt on a 5,000-acre test area to reduce the estimated deer population from 300 to 150. Other biologists immediately questioned the idea. They maintained that much like gas molecules that migrate from an area of dense concentration to a lower one, deer from the surrounding areas would move to a less populated area. If their goal were to regenerate trees on 5,000 acres, deer would need to be removed from a much larger area. Since some of the biologists were betting men, the experiment became the subject of a wager with the stakes set at a case of beer. Did the deer behave as gas molecules? Over five years, the population was reduced by 50%. Deer from the surrounding areas did not behave like gas molecules. The wager lost and the beer handed over. So why didn t the deer fill the void? The biologists concluded that deer outside the removal area were too strongly attached to their home range to be drawn to any other area. Genetic analyses suggest that each summer range is shared by a group of related individuals, probably the daughters, granddaughters and great-granddaughters of a single female. Deer from adjacent areas did not move into the area over a 10-year period. 2. Grazing Uplands Changes Diet and Habitat Preferences Herders, who understand and practice low-stress livestock handling (LSLH), can move and place livestock on uplands and away from riparian areas. There are many benefits of LSLH but one possible benefit is a change in cattle behavior. Over time, consistently moving cattle to uplands will likely require less time and effort as cows Producer s Update and Research Highlights

22 learn new places to forage and they are not bothered by herders as long as they re in the uplands. Their daughters (replacement heifers) will learn to forage in the uplands. They will acquire preferences for upland forage because dietary experiences early in life have a huge effect on food preferences later in life. Early dietary experiences can improve feed efficiency and intake, change the physiology, neurology and/or structure of the body and may even change gene expression. Which means cattle are less likely to return to loitering in riparian areas if favorite foods are in the uplands. 3. Replacement Heifers: To Buy or Not to Buy Economists often recommend buying replacement females because it s cheaper. Unfortunately, they rarely take into account that replacements are not created equal. One rancher referred to the time he bought in replacements as the year from hell. New animals often walk the fences, gain poorly, suffer more from predation and illness, and are sometimes hard to find on the range. Ranches with harsh conditions (poor-quality or sparse feed, rough terrain, few watering points, etc.) should look hard at the economics of raising replacement heifers. Buying replacements may be a viable option if heifers are coming from a ranch similar to yours, and they perform nearly as well as cattle raised on your ranch. However, we ve heard stories of cattle doing poorly when moved from relatively harsh conditions to good rangelands and cattle still perform poorly. If you raise your own replacements but supplement them heavily until they are yearling, you may want to consider the way one ranch in Nevada raises its replacement heifers. On the Zimmerman Ranch replacement heifers are not weaned with the steers. Heifers are left with their mothers to learn how to survive on the desert. They must learn where to go when it storms and there s a shortage of water or forage. They need to know how to use a country that is long on feed but short on water and to eat snow so they will not have to travel long distances to water. A heifer must learn these things so she will know how to care for herself and her calf. Her mother weans her at the proper time. Zimmerman says If we did wean her by keeping her in the fields to put on weight and then sent her back to the desert the following winter as a bred heifer, we would be signing her death warrant. 4. The Hazards of New Environments. Ignorance of behavior can be devastating. Mick Holder, an Arizona rancher, writes: Gila County is mercifully deficient in poisonous plants, but we have lupine and loco in small or moderate stands. In 30 years of ranching, I never had a problem with either. I leased rangeland in Apache County and moved part of my cattle to that location during a drought and suffered severe losses to poisonous plants, while the sister cattle left in Gila County on equally poor rangeland didn t have one case of loco or lupine poisoning. Did they not recognize the plants because they had been relocated 100 miles east? It may seem strange, but animals prefer familiar to unfamiliar foods, even if familiar foods are toxic, especially in unfamiliar environments. Cattle moved to Apache County preferred familiar, toxic foods to unfamiliar foods. Holder summed it up: The only plausible explanation I would make after reading your paper is that moving cattle to Apache County suspended their aversions to familiar plants - loco and lupine - due to the unfamiliar settings or the lack of diversity of browse found in the Pinyon-Juniper habitat... painful lesson for us both. There also is evidence that the same dose of a toxin has a much greater effect in an unfamiliar environment compared to a familiar one. The added stress increases the toxin s effect on the animal. Thus, cattle may have eaten amounts of toxic plants that were not lethal in the familiar environment but lethal in the unfamiliar environment. Feeding animals familiar, nutritious foods while they adapt to unfamiliar environments can mean the difference 22 Producer s Update and Research Highlights

23 between life and death. One last point, if you re moving animals to a new location to forage during drought, winter, etc., your cattle to may not gain as well as the cattle raised in that area. I m not suggesting moving them to a new area is always a bad idea. It can make economic sense. However, you may overestimate cost per pound of gain if you count on your cattle gaining at the same rate as cattle reared in the area. Recommendations for Offering a Choice of Foods to Finish Livestock What are the advantages of letting animals select their own diets? 1. Lower feed costs as much as 20% due to improved feed efficiency and animals tend to eat more of the less expensive foods but gain at the same rate as animals eating a total mixed ration. 2. Don t need a nutritionist to balance the ration 3. No need to mix feed 4. Animals can meet individual needs 5. Animals of different sizes and ages can be fed together 6. Take advantage of cheaper feeds when available 7. Less illness especially acidosis 8. May not need to feed everyday What should I feed my animals when offering a choice? 1. An energy source. Examples: corn, barley, oats, beet pulp. 2. A source of protein. Examples: wheat-midds, distillers grains, soybean meal, cottonseed meal. 3. Roughage. Examples: alfalfa, grass hay, oat hay, corn silage, haylage. Mark Kossler, Turner Enterprises, feeds his bison wheat midds, whole corn, grass, alfalfa and oat hay. Kent Fullerton, Iron Mountain Bison Ranch, used corn, dried brewer s grain and alfalfa hay. In our study, we used alfalfa hay, corn silage, corn and barley. For more feed options see Nutritional value of feeds.xls on the BEHAVE Website. You may also want to look at Understanding feed analysis.pdf. How do I determine which feed is the best value? The following resources are on the BEHAVE website: 1) Feed costs calculator helps you estimate the cost of a feed or nutrient including: feed, waste, transportation, storage, and feeding costs; 2) What does that nutrient cost? Helps you compare the cost of a nutrient in different feeds but without the additional costs listed in the worksheet above. You can get the nutritional content of feed from the feed tag or use Nutritional value of feeds.xls. When comparing the cost of nutrients in a feed, remember to compare the cost of protein (CP) in high-protein feeds and energy (TDN, DE, ME) in high-energy feeds. Roughages can fall into either category. How many choices should I offer? At a minimum three, an energy source, a protein source and a roughage. If you re feeding good-quality alfalfa as your roughage, I suggest you offer a poor quality roughage as well. Good-quality alfalfa is too high in protein for cattle and bison to have as their only roughage source. It actually makes a better protein source. Bison are excellent at utilizing poor quality roughage; use that to your advantage. Producer s Update and Research Highlights

24 Most (and there aren t that many) feeding studies with bison offer them a choice between one hay and one concentrate ration but offering a choice of at least three foods may improve results. Offering even more choices may further improve performance. In a study with dairy goats, offering goats a choice of six foods rather than four resulted in higher milk yields and better feed efficiency. Researchers speculated that giving animals more choices in grains and high-protein feed sources might overcome any possible imbalances in nutrients supplied to the animal and/or rumen microorganisms. While the amount of nutrient supplied to the animal by the diet is important, how quickly or slowly a nutrient is released by digestion in different feeds also matters. Nutrient utilization is most efficient when nutrients are released at the same rate. Adding another choice will likely increase costs which needs to be considered before adding another feed. How do I get my animals eating concentrates and avoid health problems? For cattle or bison (and most herbivores), mixing grain with chopped roughage and slowly reducing the amount of roughage will also work. Just watch for scours, animals off-feed, etc., as you re putting them onto concentrates. Can I change feeds to take advantage of lower prices? Changing feeds is no problem. Just mix the new food with the old one for a week or two to help animals accept the new food and avoid any possible digestive problems. They ll rebalance their ration as needed. For more information: extension.usu.edu/behave or contact Beth Burritt at beth.burritt@usu.edu or phone (435) Producer s Update and Research Highlights

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27 You are What Your Mother Eats; Does This Apply to Your Cows? Nathan M. Long The University of Arizona Department of Animal Sciences Tucson, Arizona Department of Animal Sciences, The University of Arizona The beef cattle industry in the western US is dominated by spring-calving cows due to the philosophy of calving 55 days before the onset of green forage. In the Intermountain west forage quality and quantity is often impacted by unpredictable cyclic droughts. Forage protein content normally peaks in late spring and then declines to a low level in September. Thus pregnant cattle grazing rangelands, especially drought-stricken areas, are faced with limited forage resources and significant periods of nutritional deficiencies often coinciding with the early gestational period. This is not limited to the western US. Fall calving herds in the southern Great Plains experience reduced forage quality during winter a time that corresponds to early gestation. Evidence in other species suggests that changes in the structure and/or function of fetal organs and tissues resulting from a bout of early maternal nutrient restriction may have lasting effects on body composition, growth efficiency and health status of offspring in postnatal life. Thus, most beef cattle under extensive forage-based production systems in the Western United States and possibly other locations in the US are exposed to periods of inadequate nutrition during early gestation leading to the quality of their offspring being compromised. Fetal programming is the well accepted concept that fetal stress such as reduced nutrient availability during gestation can result in negative impacts on a fetus s prenatal and postnatal life. Within animal production research intrauterine growth restriction (IUGR) is most commonly used as evidence for fetal nutrient deprivation because it is easily measured by taking fetal weights and fetal dimensions. Another important concept is that there are specific windows of sensitivity during fetal development where nutrient deficiencies will have the greatest impact on prenatal and postnatal growth and development. Early gestation is the time when critical changes occur in the cellular composition of organs and tissues and normal cellular composition of organs and tissues is necessary for their proper function after birth. Organs like the heart, pancreas, kidneys, brain and important tissues like skeletal muscle and adipocytes (fat cells) are all undergoing development during this period. Mammalian offspring that have experienced IUGR are known to have an increased risk of developing obesity, type II diabetes, hypertension and cardiovascular diseases in postnatal life. To confirm the negative impacts of early maternal undernutrition on fetal growth and development in beef cows several recent experiments have been conducted. From day 30 to 125 of gestation one group of cows were fed normally to allow body weight gain during pregnancy while another group of cows (nutrient restricted) were fed 70% of energy and 87% of protein requirements. At day 125 of gestation a group of normal fed and nutrient restricted cows were harvested and fetal, placental and maternal measurements were recorded. The remainder of the normal fed cows continued to be fed to requirements while the nutrient restricted cows were refed after day 125 of gestation to achieve a body condition score equal to normal fed cows by 220 days of gestation. Both normal fed and nutrient restricted-refed cows were harvested at 245 days of gestation. Nutrient restricted cows lost 95 lbs and 0.4 body condition score units from day 30 to 125 of gestation while normal fed cows gained 50 lbs and 0.2 body condition score units. In the nutrient restricted cows harvested on day 125 of gestation there were two distinct groups of fetuses. One group of fetuses was markedly smaller (~20%) with reduced liver and lung weights and increased brain and heart weight (indicative of fetal IUGR) than the remaining fetuses from nutrient restricted Producer s Update and Research Highlights

28 cows or normal fed fetuses which were similar in weight to fetuses from normal fed cows. Intriguingly, the nutrient restricted cows with IUGR fetuses on day 125 were younger (3.5 years of age) than the nutrient restricted cows gestating normal weight fetuses (5.0 years of age). In contrast, when cows were harvested in late gestation, fetal size and organ weights were similar between fetuses gestated by nutrient restricted-refed and control cows. Interestingly, however, despite similarities in kidney weight of fetuses from control and nutrient restricted-refed cows absolute glomerular number, the functional unit of filtration in the kidney, was markedly reduced in fetuses from the nutrient restricted-refed group. This is the first study in the cow that the authors are aware of demonstrating a significant decrease in fetal growth during mid gestation in response to a global dietary restriction during early gestation. Fascinatingly this fetal IUGR occurred in younger cows but not in older cows. A similar study looking at nutrient restriction in heifers showed that steers offspring of nutrient restricted heifers had reduced numbers of skeletal muscle fibers compared to steers offspring from heifers fed to requirement. These alterations in fetal skeletal muscle growth could result in alterations in muscle growth postnatally. This could lead to a decreased carcass skeletal muscle mass in steers from cows that were exposed to nutrient restriction during early gestation. These data suggest that early gestational undernutrition in the cow herd can lead to IUGR and altered fetal organ and tissue growth. If however, as is common practice, cattle are given nutritional supplements from mid through late gestation normal birth weight will be achieved. This presents a problem for producers as they have no way of confirming which calves experienced IUGR in utero and may be of poorer quality. Further, fetuses of young cows appear to be more susceptible to early maternal nutrient deprivation then those of old cows suggesting that early gestational supplementation of undernourished young cows is advisable if IUGR is to be avoided. Therefore, adequate early gestational nutrition is of high importance for normal fetal growth and development and offspring quality, particularly in young cows. Producers should devote more effort to ensure adequate nutrition and proper body condition of young cows during early gestation. 28 Producer s Update and Research Highlights

29 Maternal Stress Causes Fetal Metabolic Adaptations that Lower Postnatal Performance Sean W. Limesand The University of Arizona Department of Animal Sciences Tucson, Arizona Department of Animal Sciences, The University of Arizona Some of the most debilitating diseases affecting public health and those that impose an extreme monetary impact on health care costs in the United States are metabolic diseases and endocrine disorders such as Type 2 Diabetes. The prevalence of these diseases in the USA has been growing faster than Mendelian inheritance rates suggesting that environmental cues are influencing the prevalence of Diabetes and other adulthood diseases. Inappropriate fetal programming has been associated with several adult onset diseases (Barker Hypothesis). For example increased susceptibility to diseases such as coronary heart disease, hypertension, insulin resistance and Type 2 Diabetes has been associated with low birth weights caused by inappropriate fetal growth. During embryonic life cellular expansion and differentiation coordinate the development and growth of tissues and organs to shape an adult. Insult or stressful events during critical developmental periods in fetal life might alter an individual s physiological function and limit their ability to respond to normal or stressful situations, thus increasing a person s susceptibility for medical complications throughout their life. Our work confirms one such relationship, and it indicates that fetal nutrient deprivation impairs development and function of the insulin-producing β-cells, which also will promote fetal growth restriction because insulin is a prominent anabolic hormone in the fetus. Insulin secretion and action are a metabolic process central many of the adulthood pathologies listed, and therefore, adaptive responses to endocrine regulation of glucose homeostasis might reflect a major site for fetal origins of adult disease. In addition to the clinical ramifications for the developmental origins of adult disease, animal agriculture may also suffer from fetal programming. Fetal growth restriction occurs in a variety of practical production situations, such as: multifetal pregnancies due to improved reproductive management, undernutrition because of limited forage, illness, and exposure to warm or cold environments. It is apparent that environmental factors influence the set points of several metabolic pathways during fetal development, including the placental transfer of nutrients. Fetal adaptations to a low nutrient supply are critical for the completion of fetal development but might be detrimental after birth if the adaptations persist, or are over-corrected in response to sufficient postnatal nutrients. The significance of these studies can be divided into four areas that influence livestock production: (1) prenatal and perinatal death losses, (2) postnatal growth rates, (3) reproductive fecundity, and (4) carcass characteristics at harvest. These areas may not be recognized until adulthood, or remain as an unforeseen expense absorbed by livestock producers. My research objectives are to determine how in utero insults increase an animal s susceptibility to postnatal complications long after the fetal insult has occurred and/or been corrected. To study fetal responses to nutritional insults I have chosen sheep as a model system because the pregnant ewe tolerates chronic fetal catheterization better than other animals, allowing us to study fetal insulin secretion and glucose metabolism during nutrient restriction. Additionally, several methods for creating intrauterine growth restriction (IUGR) in sheep fetuses exist, which provides an extensive background for studying normal and compromised fetal physiology. In the USA the sheep industry is prominent, which allows us to translate our work on heat stress in sheep to ranchers, but sheep are a long-standing model for fetal physiology in humans and other domestic livestock species. This increases the impact of my work in both biomedical and agricultural applications. Producer s Update and Research Highlights

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31 Sire Selection For Your Environment and Cow Herd David W. Schafer The University of Arizona Department of Animal Sciences Tucson, Arizona Department of Animal Sciences, The University of Arizona Sire selection is the most important decision a cow/calf producer makes. A bull contributes fifty percent of the genes in your calf crop. Your herd s rate of genetic improvement revolves around the herd bulls you choose to use either naturally or via artificial insemination (AI). Assuming, a producer uses a bull for four years and his daughters are retained, his influence, be it positive or negative, will easily extend into the next decade. Additionally, if you have retained granddaughters or great-granddaughters, his influence could potentially last up to 25 years. Therefore, it behooves every cow/calf producer to really put some thought into their breeding program and their production goals. Start by writing down some goals you would like to achieve with your cow herd. Do you want to be a seedstock provider or a commercial producer? Think about specific production goals you have relative to weaning weight, cow pregnancy rates, or any other traits or practices that are important to you. Also, will you keep your own replacement heifers or do you plan on purchasing them? Once you have some goals in mind, then you can begin to formulate a plan to achieve them. Next, take time to evaluate the resources at your disposal. Consider feed availability, labor, facilities and marketing opportunities. Categorize the feed and labor into low, medium or high availability. Table 1 shows an example of how you can use these classifications to make selection decisions. Not all traits are represented but it gives you an idea of how to use this information and you can build your own table. Finally, make a list your marketing options. Taking the time to write these things down will help you in selecting the genetics that best fit your environment and production goals. If you already have an established cowherd, do a herd assessment. If your cows are individually identified and you have already collected data on them, this should be fairly straightforward. However, you can do this even if you have not individually identified your cows. Determine the breed makeup, the production level and mature size of your current herd. If your breed makeup is largely one breed, maybe you want to consider using a bull of a different breed. If you feel your weaning weights are lighter than they should be, then maybe you need to place some selection emphasis on that trait. The point is that you know your herd and you should be able to characterize them in such a way that you can use that information to help you make selection decisions. Now that you have your goals and resources identified, it is time to choose the genetics that match your resources and production goals. Take time to study the various breeds, get to know the strengths and weaknesses of the different breeds. Where would they fit relative to the classifications in Table 1. Recognize that no one breed can do it all whether you are a seedstock provider or a commercial cattleman. Seedstock breeders need to know not only the strengths and weaknesses of their chosen breed but also the strength and weaknesses of other common breeds so that they can assist their customers with their breeding programs. Commercial cattlemen should also learn about the breeds so that they may make well informed decisions when it comes to choosing their next herd sire. Do not fall victim to the bull of the month club. Do your homework, make a plan and try to stick to it. Be careful though not to develop tunnel vision. Try to remain flexible and open to new ideas while always keeping your goals in mind. Producer s Update and Research Highlights

32 Part of the process of selecting the breeds to use in your program should include researching available breeds in your area. If you plan to use AI, then pretty much any breed can be purchased. However, if you plan to mate your cows through natural service, it may not make sense to select a breed that is hard to find or that you have to travel hundreds of miles to get. Try to identify seedstock sources that raise their cattle in an environment similar to yours. Selecting bulls that have been overly pampered or raised in a lush environment and then turning them out on the desert is not likely to end well. Commercial cattlemen should really consider using a crossbreeding system to take advantage of heterosis and breed complementarity. Heterosis is that extra boost in performance that you get from crossing two unrelated breeds. The technical definition would be when the average of the progeny exceeds the average of the two parental breeds. For instance, Breed A has an average weaning weight (WW) of 550 pounds and breed B has an average WW of 500 pounds. When you average those two parental breeds you get 525 pounds. However, the average WW of the AB cross calves is found to be 546 pounds or 21 pounds heavier than the parental breed average. The amount of heterosis in this example would be 4% or 21 divided by 525. Breed complementarity simply refers to crossing animals of differing strengths and weaknesses that complement each other. For example, crossing a non-heat tolerant breed with a more heat tolerant animal to form an individual better suited to a particular environment and market place. Let us now turn to the tools that are available to help you make your selection decisions. There continues to be numerous advances on the molecular side to enhance our selection decisions. However, we are still a ways off from having that information incorporated into mainstream sire evaluations. So, today Expected Progeny Differences (EPDs) remain the most accurate and significant tools we have to date for making genetic change. EPDs can be defined as the expected performance of future offspring of a parent compared to the expected performance of future offspring of other parents within the analysis when bred to mates of equal value. In other words, when two bulls are mated to the same cows what is the expected difference in performance of the offspring for the trait in question? EPDs should not be directly compared across breeds. They are designed to be used within the breed in which they were calculated. EPDs are calculated for a number of economically important traits. An EPD is calculated using the individual s performance records in conjunction with the performance records of all his ancestors and progeny. If the animal 32 Producer s Update and Research Highlights

33 does not have any progeny, an EPD can still be calculated and is usually called an Interim EPD and is so designated with an I preceding the EPD. A Pedigree EPD is calculated simply by adding together the Sire and Dam s EPDs and dividing by two. Pedigree estimates are usually designated with the letter P. When an EPD is calculated there is an accuracy value associated with it. This accuracy value is the reliability that can be placed on the EPD. Accuracy values range from 0 to 1.0. An accuracy value close to 1.0 indicates a higher reliability. An Interim EPD usually has a low accuracy value and a Pedigree EPD has very low accuracy associated with it. As animals produce progeny the accuracy value increases. EPDs are expressed as a relative value, not an absolute. A WW EPD of +35 pounds does not mean the calves will be 35 pounds heavier than the breed average. EPDs are a means of comparing animals. Take a look at the example below: We see that Sire A has a BW (birth weight) EPD 5 pounds heavier than Sire B, the WW EPD is 18 pounds greater, the YW (yearling weight) EPD is 26 pounds greater, and milk is 5 pounds less. So, how do we interpret the above differences? If we were to breed both bulls to the same group of cows, we would expect the calves from Sire A to be 5 pounds heavier at birth than calves from Sire B due to their genetics for birth weight. Calves from Sire A would also be 18 pounds heavier at weaning and 26 pounds heavier at yearling due to the genetics of Sire A for each of those traits. The daughters of Sire B, if used in the same environment as those daughters of Sire A, would be expected to add 5 pounds of weaning weight to their calves than the daughters of Sire A due to their milk production and maternal characteristics. It is important to remember that these values are not relative to a breed average; rather, they are relative to the production system in which the bulls are used. If for example, Sire A was siring calves with an 80 pound average birth weight in your cow herd, you would expect calves from Sire B to weigh and average 75 pounds when used across the same group of cows. Sire selection is one of the most important decisions a cow-calf producer makes in any given year. If you are retaining replacement heifers then the future of your cowherd depends on the selection decisions you make now. Genetic change is permanent change. Sire selection has a long-term impact and should be viewed as a long term investment into the efficiency and adaptability of your beef operation. The National Beef Cattle Evaluation Consortium has compiled a Beef Sire Selection Manual that provides greater detail than can be covered in this article. The manual is available online at producers/sire.html or if you prefer a hard copy, there is information regarding who to contact. The manual is free you simply pay shipping and handling. Producer s Update and Research Highlights

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36

37 Change on the Range: Ten Years of Rangeland Monitoring on the Tonto National Forest Jim E. Sprinkle 1, George Ruyle 2 and Michael Crimmins 3 1 Department of Animal Sciences and Arizona Cooperative Extension 2 School of Natural Resources & the Environment 3 Department of Soil, Water and Environmental Science The University of Arizona Department of Animal Sciences, The University of Arizona A collaborative rangeland monitoring program lead by the University of Arizona, Reading the Range, was initiated on the Tonto National Forest in 2001 with four grazing allotments encompassing 100,000 A. Since that time the monitoring program has grown to now include 42 allotments encompassing 1,094,710 A. Previous research has demonstrated an improvement in working relationships between agency employees and ranchers as a result of monitoring. The objective of these data collection for this project is to report on observations related to changes in vegetation as influenced by climate and management over a broad geographic landscape from Upper Sonoran desert at 2,365 ft. to Ponderosa pine/douglas fir woodlands at 6,565 ft. In 2002, a drought of epic proportions occurred, which according to 1,000 years of tree ring data, was equaled in severity only by the years 1904, 1773, 1685, 1664, and 1150 AD. Low elevation ( 2,300 ft.) clay flats dominated by a browse overstory have remained largely unchanged over the years of data collection. Similarly, higher elevation grassland savannah or woodland dominated sites > 5,500 ft. have shown little change. However, mid elevation (4,000 to 5,500 ft.) grassland savannah monitoring sites at some locations from the pinyon-juniper vegetation zone have demonstrated considerable variation in vegetation attributes and forage production. On one allotment, a grazed site was compared to an isolated butte in a similar ecological site which had never been grazed. The grazed site showed greater resilience (P < 0.01) with respect to the perennial grass community. In 2001, preceding the drought, the relict site had 42% of the total plant production (by dry weight rank; DWR) that was accounted for by perennial grasses while the companion grazed site had 57%. In 2003, the perennial grass DWR for the relict site was 2% compared to 19% for the grazed site. In 2009, the relict site had 12% DWR perennial grasses compared to 55% for the grazed site, and in 2010, 1% vs. 20%. On an adjacent allotment, forage production from perennial grasses and palatable half shrubs at one site varied from 54 ± 21 lbs/a in 2003 to 1,256 ± 304 lbs/a in In the same pasture 1 mi. distant, forage production in 2003 was 436 ± 122 lbs/a and in 2005, 1,534 ± 381 lbs/a. In a large pasture of the same allotment characterized by large flat mesas, a cross fence was installed in 2001 to control concentrated livestock grazing that had occurred over several decades. In 2001 before the cross fence was installed, DWR from perennial grasses was 8%. By 2009, DWR from perennial grasses on the same site had increased to 40%. Perennial grass forage production on the site was estimated at < 100 lbs/a in 2001, but grass production alone since 2006 has ranged from 218 ± 117 lbs/a in a dry year to 735 ± 319 lbs/a in a wet year. Given the dynamic nature of vegetation responses to climate in the mid elevation zone of the Tonto National Forest, it is imperative that adaptive management be practiced. Producer s Update and Research Highlights

38 Effects of a Long Acting Trace Mineral Rumen Bolus Upon Range Cow Productivity 1 Jim E. Sprinkle 2, David W. Schafer 2, S. Peder Cuneo 2, Doug Tolleson 2 and R. Mark Enns 3 2 The University of Arizona, Tucson, Arizona 3 Colorado State University, Fort Collins, Colorado ABSTRACT: The objectives were to determine if strategic supplementation of range cows in central Arizona with either 2 or 4 long acting (six mo) trace mineral rumen boluses containing Cu, Se, and Co would: (1) decrease yearly calving interval; (2) increase cow body condition, milk production, or calf adjusted weaning weights; and (3) to see if any of the above traits varied by cow breed. There were 194 Hereford (H) and 132 Composite (CGC; 50% Red Angus, 25% Tarentaise, 25% Charolais) control cows, 173 H and 125 CGC 1X treated (2 boluses in late winter) cows, and 183 H and 117 CGC 2X treated (2 boluses in autumn and 2 in late winter) cows used over the four year period. Cows were weighed and scored for body condition (1 to 9, 9 = fattest) in February, May, and September of each year. Milk production was determined by weigh-suckle-weigh on a subset of cows (n = 169) at 50 d lactation. Cow body condition score and calf adjusted weaning weights differed by breed and treatment (P < 0.05) with weaning weights being greater (P < 0.05) for calves from 2X cows than for control calves. Milk production differed by year (P < ) but did not differ by either breed or treatment (P > 0.05). Calving interval was 389 ± 2.7, 382 ± 3.2, and 378 ± 3.2 d for control, 1X, and 2X treatments, respectively and calving interval declined (P < 0.05) from the control to the 2X treatment group. Strategic supplementation via a long acting trace mineral bolus was successful in decreasing calving interval and increasing calf weaning weights from cattle grazed in an extensive rangeland environment. 1 We acknowledge the support of the Arizona Experiment Station and Telsol Ltd, manufacturer of Cosecure, P. O. Box HH7, Leeds, United Kingdom LS8 2YE. Mention of a proprietary product does not constitute a guarantee or warranty of the product by Arizona Experiment Station, University of Arizona, Colorado State University, or the authors and does not imply its approval to the exclusion of other products that may also be suitable. We extend our thanks to Bopper and Keith Cannon, Wade and Maggie Woodbury, and Mingus Union FFA for helping with this project. Introduction A long acting (6 mo) rumen trace mineral bolus containing Cu, Se, and Co has been developed in the United Kingdom (Cosecure, Telsol Ltd., Leeds, United Kingdom) and has shown promise for helping alleviate trace mineral deficiencies (Sprinkle et al., 2006). One advantage of the long acting rumen boluses is the capability to provide a trace mineral supplement on rugged topography rangelands that are inaccessible by motor vehicles. Sprinkle et al. (2006) found that use of the Cosecure bolus caused increased weight loss (P = 0.02) from late gestation to early lactation, but milk production was not determined in that study. Also, the same study did not report on the effect of the long acting rumen boluses upon yearly calving interval. The objectives of this study were to examine the effects of the Cosecure boluses supplemented either once or twice per year upon body condition score (BCS), body weights, yearly calving interval, and milk production as well as calf weaning weights; and to determine whether breed response for the above traits differed. Materials and Methods Range site. The study site for this experiment was the 71,000 A. V-V Ranch operated by the University of Arizona and 38 Producer s Update and Research Highlights

39 located near Camp Verde, Arizona. The ranch ranges in elevation from approximately 3,200 ft. to 7,200 ft. Average yearly precipitation ranges from 13 in. at the lower elevations to 27 in. at the upper elevations. However, annual precipitation during the course of this trial was quite variable (Arizona State Climate Office, 2011): with more winter moisture in 2005 before the study commenced; substantially less annual precipitation in 2006; about the same (lower elevations) and slightly less (upper elevations) annual precipitation in 2007; an El Niño winter occurred in 2008 at all elevations with more annual precipitation at upper elevations (31.5 in. and similar precipitation (12.2 in.) at lower elevations; and substantially less precipitation at all elevations (7.1 in. for lower elevations, 18.1 in. for upper) in 2009, particularly during the midsummer and early fall growing season for warm season grasses. Forage Sampling. Forage was sampled by hand clipping four times a year (January, April, June or August, and September) from four different locations on the ranch as described by Sprinkle et al. (2006). Prior to mineral analysis, forage samples were air dried at ambient temperatures for one year, then shipped to the Oscar E. Olson Biochemistry Analytical Services Laboratory in Brookings, SD where they were ground to pass through a 1 mm screen using a Tecator Cyclotec cyclone pulverizing mill (AOAC, 2005). Samples were then mixed and moisture determined (on a subsample) at 105 C for 3 h in a mechanical convection oven (Method 2.1.4, NFTA, 2006), then analyzed fluorometrically for Se following digestion in percholoric and nitric acids and reduction with 0.1 M HCl and complexation with diaminonapthalene (AOAC Official Method , AOAC, 2005). Following these analyses, the samples were shipped to Dairy One Lab in Ithaca, NY and analyzed for Ca, P, Mg, K, Na, Fe, Zn, Cu, Mn, Mo, Co, and S using inductively coupled, plasma emission spectroscopy as described by Sirios et al. (1991). Animals. The trial commenced in October 2005 and concluded in September Treatment and control cattle were randomly allocated at the onset and remained in each treatment group throughout the three-yr trial. There were 194 Hereford (H) and 132 Composite (CGC; 50% Red Angus, 25% Tarentaise, 25% Charolais) control cows, 173 H and 125 CGC 1X treated (2 boluses in late winter) cows, and 183 H and 117 CGC 2X treated (2 boluses in autumn and 2 in late winter) cows used over the four year period. Cows ranged in age from 2 to 12 and 2 to 10 yr for H and CGC, respectively. In September or October and February or March of each yr, cows in the 2X treatment groups were orally dosed with two 100 gram Cosecure boluses consisting of 0.30% (wt/wt) selenium as sodium selenate, 13.4% (wt/wt) copper, and 0.5% (wt/wt) cobalt. The 1X treatment group only received boluses in February or March. According to company literature validated with rumen fistulated cattle on a silage and concentrate ration, boluses dissolved in 175 days and released 156, 5.9, and 3.4 mg/d of Cu, Co, and Se, respectively. A subset of mature cattle (5 to 10-yr-old) from each treatment group was sampled for milk production near expected time for peak lactation (50 d) in 2006, 2008, and 2009 using the weigh-suckle-weigh technique described by Williams et al. (1979). There were 26 CGC Control, 31 CGC 1X, 28 CGC 2X, 28 H Control, 26 H 1X, and 30 H 2X cows used over all three years of milk production data collection. Cattle were not sampled in 2007 due to a lack of an adequate sample size at peak lactation. Cattle remained in a common herd and moved through 37 upland pastures from low and mid-elevation in winter and spring to high elevation in late summer and fall in a modified Holistic Range Management grazing plan. Cattle did not receive any type of oral trace mineral supplement for the four years of the trial except for free choice white iodized salt blocks and the incidental minerals contained in protein blocks used from April to June in 2006 and from March to May 15 in 2008 (27% crude protein, 17 ppm Cu, ppm Se, Eagle Milling Co., Inc., Casa Grande, AZ). At an average daily protein supplement intake of kg in 2006 and kg in 2008, it was estimated that cattle received an additional 16 mg/d of Cu and 0.28 mg/d Se in 2006 and 7 mg/d of Cu and 0.12 mg/d of Se in Producer s Update and Research Highlights

40 The majority (74%) of calves born in this trial were sired by Hereford bulls via artificial insemination or pasture exposure. Other sire breeds represented were Waguli (13%), Tuli (4%), Wagyu (3%), Red Angus (3%), Angus (2%), and miscellaneous (1%). Breeding seasons extended from May 20 to September 6 in 2005, May 18 to August 30 in 2006, May 15 to September 20 in 2007, May 23 to September 4 in 2008, and from May 22 to August 5 in Cows were artificially inseminated once following estrus synchronization using Easi-Breed CIDRs (Pharmacia & Upjohn Co., Kalamazoo, MI), then pasture exposed to bulls. In September to October and February to March, cows were checked for pregnancy by rectal palpation. Cattle were weighed and scored for BCS (1 to 9; 9 = fattest) in February or March, May or June, and September or October. Birth and weaning weights were collected on all calves. The majority of the calves were weaned in October at approximately 182 d and weaning weights were adjusted to 205 days of age and for age of dam according to BIF (1990) guidelines. Statistical Analyses. Data were analyzed using a restricted maximum likelihood-based mixed effects model appropriate for repeated measures (SAS Inst., Inc., Cary, NC) with the categorical, fixed effects of breed, bolus, and year with the interactions of breed x bolus, and breed x year. For adjusted weaning weight, year x bolus was added. Cow within breed by bolus was included as a random effect. Calving interval had only the breed x bolus interaction added. Age of dam was added as a covariate to all models. Milk production used the same model as calving interval with the added covariate of post partum interval. The denominator degrees of freedom for treatment F-statistics were approximated using the Kenward-Roger s method. For all models except calving interval, a heterogeneous autoregressive structure was used as a covariance structure to model the relationships between repeated observations. In order for calving interval to properly converge with this iterative methodology, a simplified compound symmetry covariance structure was used. Treatment means for all statistical models were separated using the PDIFF function in SAS (SAS Inst., Inc., Cary, NC). Results Overall Forage Trace Mineral Concentrations. Concentrations of Cu in forage were adequate (10 ppm; NRC, 1996) in 2006 (12.1 ± 1.70 ppm), nearly adequate in 2007 (8.9 ± 1.21 ppm), adequate in 2008 (10.2 ± 0.88 ppm), and nearly adequate in 2009 (7.5 ± 0.38 ppm). The concentrations of Se were always deficient in forage (< 0.1 ppm; NRC, 1996), being ± ppm in 2006, ± ppm in 2007, ± ppm in 2008, and ± ppm in The other trace mineral provided by the boluses, cobalt, was not a concern for this ranch, always being well above the NRC (1996) minimum requirement (0.10 ppm), averaging 1.2 ± 0.13 ppm over all the years of the trial. We did not detect any antagonistic relationships for either Mo of S in the forage but Fe concentrations in the forage exceeded 600 ppm in 2006, 2008 and 2009 and was 398 ppm in Corah and Dargatz (1996) reported that Fe levels exceeding 400 ppm reduces Cu absorption. Cow Performance Data. Cows bolused with the 2X Cosecure bolus treatment had less body condition in the spring than did either control cows (P = ; Table 1) or 1X treated cows (P = ; Table 1), though the actual difference was small. However, a loss of body condition is verified between control and 2X treated H cows by spring cow weights (P = ; 2X H = 959 ± 10.8 vs. 988 ± 10.6 lbs for control H; Table1). There was also a tendency (P = ; Table 1) for 1X treated H cows to weigh more than 2X H cows. This trend continued into the fall for H cows, with the 2X cows having less BCS than did 1X cows (P = ). Interestingly, an opposite effect appeared to be in place for CGC cows for fall weight, with 2X cows weighing more than 1X cows (P = ; Table 1). In the study reported by Sprinkle et al. (2006), cows bolused 1X with Cosecure boluses lost more weight from late gestation to early lactation than did control cows (P = 0.020). The authors hypothesized that this may have been due to increased milk production for treated cows. In this study, we did not find any differences (Table 2) for either breed (P = ) or treatment (P = ) for milk production at 50 d estimated by weigh-suckle-weigh (Williams et al., 1979). We speculate that 40 Producer s Update and Research Highlights

41 environmental variation may have overwhelmed treatment differences. Indeed, the only significant difference detected for milk production in this study was for year (P < ) with greater milk production following a wet El Niño year in 2008 (15.7 ± 0.66 lbs/24 h) compared to 2006 (11.5 ± 0.68 lbs/24 h) and 2009 (12.8 ± 0.66 lbs/24 h). Year effects were important (P < ) in this study for all variables measured except for calf birth wt (P = ). Breed effects were detected for differences in weight change from spring to fall (P = ; Table 1) and for fall weight (P = ; Table 1). Calf Performance Data and Calving Interval. Calf birth weights tended to differ by bolus treatment (P = ), being smaller (P = ) for control cattle than for 1X treated cattle (Table 2). Breed effects were detected for differences in adjusted weaning weight (P < ; Table 2), and calving interval (P = ; Table 2). It was expected that breed differences could occur with some of these production characteristics considering we were comparing crossbred vs. purebred cattle. The CGC composite cattle had shorter (P = ) calving interval periods than did H cattle (376 ± 2.2 vs. 390 ± 2.9 d) and weaned heavier (P < ) calves (452 ± 4.0 vs. 401 ± 3.1 lbs). The most striking results from this trial were the effects of increasing trace mineral supply via the boluses upon weaning weight and calving interval. There was a linear increase for weaning weight and linear decrease for calving interval with increased trace mineral supply, being significant at the 2X level for both weaning weight (P = ; Table 2) and calving interval (P = ; Table 2) when compared to control cattle. Calves from the 2X treatment weighed lbs more than did calves from control cattle and cows on the 2X treatment had yearly calving intervals 11 d shorter (Table 2). For H cattle, cows on the 2X treatment had calving intervals 14 d smaller (P = ) that did control cows. Other research has reported variable results for added Cu, increasing ADG during finishing trials (Ward and Spears, 1997) and decreasing gain for growing dairy heifers (Lopez-Guisa and Satter, 1992). Awadeh et al. (1998) and Gunter et al. (2003) failed to demonstrate any added growth performance for calves nursing Se supplemented cows while Nelson and Miller (1987) reported that weaning weights for calves nursing Se supplemented cows increased by 44 lbs. It appears that any added weight gains for calves nursing cows supplemented with either Cu or Se are dependent upon several factors, chief of which are the dietary Cu or Se concentrations for cows in the study and the presence or absence of any antagonistic trace minerals in the diet such as Mo, Fe, and S. Our pasture concentrations for Cu were adequate to mostly adequate but with a possible negative absorption influence due to high dietary Fe. Villar et al. (2002) reported that positive growth responses appear to occur when dietary Se in the forage base is less than 0.05 ppm DM. The pasture forage Se reported by Gunter et al. (2003) was 0.11 ppm and 0.07 ppm by Awadeh et al. (1998). Our pasture Se concentrations ranged from to ppm. Implications Strategic supplementation via a long acting trace mineral bolus was successful in decreasing calving interval and increasing calf weaning weights from cattle grazed in an extensive rangeland environment. At current 2011 calf prices, the value added from increased weaning weights to cow gross income by the 2X over the control Cosecure treatment through supplementations would be $21.74 (13.23 lbs. x $1.6438/lb, NM prices, LMIC, 23 March 2011). Added to this gross profit would be the advantages of a reduced yearly calving interval. Producer s Update and Research Highlights

42 42 Producer s Update and Research Highlights

43 Literature Cited AOAC Official Methods of Analysis (18th ed.). Association of Analytical Chemists, Gaithersburg, MD. Arizona State Climate Office, Monthly Cooperative Station Data, Accessed 11 March edu/summary/climsmaz.html. Awadeh, F. T., R. L. Kincaid, and K. A. Johnson Effect of level and source of dietary selenium on concentrations of thyroid hormones and immunoglobulins in beef cows and calves. J. Anim. Sci. 76: BIF, BIF Guidelines for Uniform Beef Improvement Programs. 6th Ed. Beef Improvement Federation, University of GA, Athens, GA. Corah, L.R., and D. Dargatz Forage analyses from cow/calf herds in 18 states. Report: Beef cow/calf health and productivity audit. U.S. Dept. of Agri. Accessed 23 March beefcowcalf/downloads/chapa/chapa_dr_forageanal.pdf. Gunter, S. A., P. A. Beck, and J. M. Phillips Effects of supplementary selenium source on the performance and Producer s Update and Research Highlights

44 blood measurements in beef cows and their calves. J. Anim. Sci. 81: LMIC Livestock Marketing Information Center, Quick Market Reports, Feeder Cattle, March 18, Accessed 23 March Lopez-Guisa, J. M., and L. D. Satter Effect of copper and cobalt addition on digestion and growth in heifers fed diets containing alfalfa silage or corn crop residue. J. Dairy Sci. 75: NRC, Pages 54 to 74 in Nutrient Requirements of Beef Cattle. (7th Ed.). National Academy Press, Washington, DC. Nelson, A. O., and R. F. Miller Responses to selenium in a range beef herd. California Agriculture. March- April:4-5. NFTA NFTA Reference Method 2.1.4: Dry matter by oven drying for 3 hours at 105 C. National Forage Testing Association, Omaha, NB. Accessed 17 March NFTAReferenceMethodDM pdf. Sirois, P. K., M. J. Reuter, C. M. Laughlin, and P. J. Lockwood A method for determining macro and micro elements in forages and feeds by inductively coupled plasma atomic emission spectrometry. Spectroscopist 3:6-9. Sprinkle, J. E., S. P. Cuneo, H. M. Frederick, R. M. Enns, D. W. Schafer, G. E. Carstens, S. B. Daugherty, T. H. Noon, B. M. Rickert, and C. Reggiardo Effects of a long acting, trace mineral, reticulorumen bolus upon range cow productivity and trace mineral profiles. J. Anim. Sci. 84: Villar, D., J. R. Arthur, J. M. Gonzalez, F. J. Pallares, and T. L. Carson Selenium status in cattle: Interpretation of laboratory results. Bov. Pract. 36: Ward, J. D., and J. W. Spears Long-term effects of consumption of low-copper diets with or without supplemental molybdenum on copper status, performance, and carcass characteristics of cattle. J. Anim. Sci. 73: Williams, J. H., D. C. Anderson, and D. D. Kress Milk production in Hereford cattle. I. Effects of separation interval on weigh-suckle-weigh milk production estimates. J. Anim. Sci. 49: Producer s Update and Research Highlights

45 Collegiate Cattle Growers Association Dan Kiesling The University of Arizona, Department of Animal Sciences Department of Animal Sciences, The University of Arizona The Collegiate Cattle Growers Association (CCGA) was established in the fall of 2005 by a group of students who were passionate about raising cattle and the Arizona beef cattle industry. The group is primarily comprised of animal sciences students but is open to, and has members from, the entire University. Since its inception, the CCGA has grown in membership and activities and is well known across the College of Agriculture for giving students practical experience and opportunities to network with members of not only the beef cattle industry but the entire Arizona livestock industry. The CCGA has also taken on several entrepreneurial endeavors including managing club livestock and assisting the UA Meat Lab in its weekly sales. In addition, there are many activities the group participates in at the University and state level. CCGA ENTERPRISES Livestock The CCGA is one of the few, if any, collegiate livestock clubs to own and manage their own livestock herds. Currently, the group owns a 20+ cow herd and small sow herd. Student managers oversee the daily management of the herds, make budgets, develop feeding rations, breeding plans and coordinate the marketing efforts of the offspring. Primary income is from the sale of club calves and show pigs. Calves are marketed at the Arizona National Livestock Show and off the farm. Pigs are sold primarily off the farm for show or are fed out and custom processed. Meat Sales The CCGA has also formed a partnership with the UA Meats Lab. The Meats Lab has a weekly sale which the CCGA has managed for the last two years. A student manager coordinates with the sales crew, takes responsibility in packaging and inventorying the product and does the advertising for the sale. This has been a great way for members to experience what happens after the livestock is dropped off at the processing facility and what goes into marketing the end product. The sales have been very successful and have built a large customer base. CCGA ACTIVITIES Homecoming Tailgate The Department hosts its annual Homecoming Tailgate party on the University mall every football season. It s a great time to welcome back alumni of the Department and the CCGA. Members join in the festivities by hosting the tailgate party and have a great time meeting with alumni and celebrating the rich history of the Department of Animal Sciences. This past year, the CCGA grilled the burgers and brats, decorated the tent and welcomed alumni back to campus as the Wildcats defeated the University of Washington in the Homecoming game! Jackpot Show The CCGA holds a Southern Arizona International Livestock Association (SAILA) sanctioned jackpot show. Members are responsible for procuring sponsorships and donations, advertising, handling registrations and organizing the show. The show is held in February at the Campus Agricultural Center on Campbell Avenue and Roger Road. This past year, over 450 entries in beef, sheep, swine and goats were exhibited and $5000 in prizes awarded. These were all-time highs in both entries and prizes. Producer s Update and Research Highlights

46 Spring Fling Carnival Students manned the booth for four days making its presence known to carnival attendees for serving delicious beef kabobs. The Spring Fling Carnival is one of the staples on the UA calendar and despite some adverse weather was well attended the first weekend in April. Annual Banquet Each year the club hosts a banquet to celebrate a year of hard work and honor members who have done exemplary work for the club. This year the banquet was held at the Mountain Oyster Club and honored Dr. Glenn Duff for years of service as advisor of the club. The 2011 livstock judging team was also introduced. An auction was held with proceeds going to both the CCGA and the judging team. It is another great way for alumni, current members and faculty and administration to get together to celebrate another year at the University of Arizona. For more information about the CCGA or to donate to the club, contact: Dan Kiesling, 520/ or kiesling@ .arizona.edu Dr. Ron Allen, 520/ or rallen@ .arizona.edu 46 Producer s Update and Research Highlights

47 Livestock Judging Team Dan Kiesling The University of Arizona, Department of Animal Sciences The Livestock Judging Team began competing and representing the University of Arizona in The team was initially started by the student Agriculture Club and competed at the American Royal in Kansas City, MO and the International in Chicago. Since then, over 320 students have competed on the University of Arizona Livestock Judging Team. Competing on a judging team helps students to improve their oral communication skills, use critical thinking and decision making, as well as foster a strong work ethic. Students have the opportunity to compete at the most renowned livestock shows in the world as well as visit some of the most elite livestock operations in the country. Networking with producers and students from around the nation gives students invaluable connections for their first job search and beyond. The 2011 team is the first judging team to be fielded since the spring of This year s team is comprised of six students: Connor Eyherabide of Litchfield Park, AZ, Zach McFarlane of Gridley, CA, Cheyenne Robinson of Cottonwood, AZ, Vicky Sanderlin of Tucson, AZ, Sylvalyn Simpson of Benson, AZ and Donny Toland of Scottsdale, AZ. The team competed in four contests this spring. Arizona National in Phoenix, AZ were the team placed fifth overall and Sylvalyn Simpson was third in sheep and Vicky Sanderlin was sixth in sheep. National Western Stock Show in Denver, CO were the team placed fifteenth overall in the livestock contest and fifth overall in carload contest. San Antonio Livestock Exposition were the team placed ninth overall and Vicky Sanderlin placed third in sheep. Lastly the Houston Livestock Show were the team placed nineteenth overall. This fall the team will compete at the Tulsa State Fair in Tulsa, OK, the State Fair of Texas in Dallas, TX, the American Royal in Kansas City, MO and the North American International Livestock Exposition in Louisville, KY. For more information about the Livestock Judging Team, contact: Dan Kiesling, 520/ or kiesling@ .arizona.edu Department of Animal Sciences, The University of Arizona 2011 Judging Team (L-R): Connor Eyherabide, Donny Toland, Zach McFarlane, Cheyenne Robinson, Sylvalyn Simpson and Vicky Sanderlin. Producer s Update and Research Highlights

48 Characterization of Uterine ph During the Estrous Cycle of the Mare Leah V Penrod 1, Stacie E Deaver 1, Erin K Prendergast 1, Glenn C Duff 2, Michelle L Rhoads 1 and Mark J Arns 1 1 The University of Arizona, Department of Animal Sciences 2 Montanta State University,, Bozeman, Montana Introduction Successful management of mares during the breeding season is one of the largest challenges for breeders. Mares being bred with fresh or cooled semen should be bred h prior to ovulation to maximize pregnancy rates. The use of frozen semen decreases the breeding window to 6 h prior to or following ovulation [1]. Current methods for predicting ovulation include the detection of uterine and follicular changes using rectal palpation and ultrasonography. In the mare, rectal palpation and ultrasonography are invasive procedures that can potentially cause damage to the rectal wall. Less invasive methods for detecting estrus and predicting ovulation would help minimize the risk of serious injury. The purpose of this study was to characterize changes in uterine ph throughout the estrous cycle and to determine if such ph fluctuations were of predictive value in regards to ovulation detection. Material and Methods A total of 8 mares (13 ± 3.3 years) of light horse breeding with normal reproductive function were utilized and housed at The University of Arizona Equine Center. Mares were offered an all alfalfa diet fed at 1% of their body weight. Estrus behavior was scored (0 to 4, aggressive and hostile behavior was scored as 0 and intense interest in the teaser and frequent urination was scored as 4) during daily teasing sessions with a stallion. Follicular development and uterine edema were monitored by ultrasonography every day from the first detection of behavioral estrus through ovulation (d0). Uterine edema was scored using Samper s [2] uterine edema scale of 0 to 5. Beginning on d 1 of behavioral estrus, uterine ph was measured each morning as described by Rhoads et al. [3]. Briefly, uterine luminal ph was measured in both uterine horns using a bench-top ph meter (UB-10, Denver Instrument, Bohemia, NY). Measurements were conducted daily during behavioral estrus and again on d 7 post ovulation. The ph microelectrode (MI-508 Esophageal ph electrode, Microelectrode Inc.,Bedford, NH) was placed in a disposable insemination catheter, which was passed through the cervix and directed to the left or right of the uterine bifurcation. The electrode was then extended 1 cm beyond the tip of the catheter into the uterine lumen. The ph meter was allowed to stabilize for approximately 3 sec before the measurement was recorded. The electrode was retracted back into the catheter, and the catheter redirected into the opposite horn, where the ph measurement process was repeated. Blood samples were harvested via jugular venipuncture into anticoagulant-coated vacuum blood collection tubes daily during estrus and every other day between d 1 and d 7 post ovulation. Plasma was stored at -20 C for analysis of progesterone concentrations by validated radioimmunoassay kit [4]. The effect of day of the estrous cycle on uterine ph, edema, serum progesterone, and their interactions were analyzed with the PROC MIXED procedure of SAS [5]. Mare was included in the statistical model as the random effect. Results Mean uterine ph for ipsilateral and contralateral horns were similar throughout all observations (Figure 1). Moreover, uterine ph did not differ during estrus and was similar to d 7 post ovulation. Uterine edema scores 48 Producer s Update and Research Highlights

49 tended to be higher (P < 0.1) during estrus and lower 7 d following ovulation. Uterine edema followed a pattern similar to what has been reported in the literature [2]. Progesterone concentrations were below 1 ng during estrus and increased (P < 0.05) to 20 ng 7 d post ovulation. Uterine ph measurements were not correlated with uterine edema scores or follicular development. 1. Mean uterine ph measurements (±s.e.m.). D 0 refers to ovulation. Discussion The objective of this study was to characterize uterine ph throughout estrus in the mare. This is the first report that documents uterine ph throughout estrus and early diestrus. Uterine ph did not differ significantly during the estrous cycle. Numerically, uterine ph was lowest around the time of ovulation. Interestingly, this is similar the findings of Parrish [6] who demonstrated vaginal ph decreases near time of ovulation in the mare. In our study, ph measurements were recorded only once daily and found to be highly variable between mares which is similar to previous reports in cattle [3]. In contrast, Parrish [6] took multiple ph readings per day, thereby increasing the number of observations within individual mares. We plan to employ this strategy in future studies to determine whether uterine ph is indicative of uterine health. Furthermore, the effects of plane of nutrition on uterine ph and subsequent embryo survival have been well documented in cattle, and will likewise be investigated for potential effects on equine fertility. Key Words Uterine ph, mare, estrus Literature Cited [1] Samper JC. Management and fertility of mares bred with frozen semen. Anim Repro Sci 2001; 68(3-4): [2] Samper JC. Ultrasonographic appearance and the pattern of uterine edema to time ovulation in mares. Proc 43rd Ann Con Amer Ass Equine Pract 1997; [3] Rhoads ML, Gilbert RO, Lucy MC, and Butler WR. Effects of urea infusion on the uterine luminal environment of dairy cows. J Dairy Sci 2004; 87(9): Producer s Update and Research Highlights

50 [4] Ginther O J, Beg MA, Gastal MO, Baerwald AR, and Pierson RA. Systemic concentrations of hormones during the development of follicular waves in mares and women: A comparative study. Reproduction 2005; 130(3): [5] SAS Software. Version SAS Institute Inc., Cary, NC, USA. [6] Parish JJ. The ph decreases in the vaginal portion of the cervix in mares near ovulation. J Anim Sci 2010; 88(E-Suppl 2): Producer s Update and Research Highlights

51 Effects of Oxytocin, LPS, and Polyunsaturated Fatty Acids on PGF2α Secretion and Gene Expression during Equine Endometrial Culture Leah V Penrod 1, Ronald E Allen 1, Michelle L Rhoads 1, Jason L Turner 2, Sean W Limesand 1 and Mark J Arns 1 1 The University of Arizona, Department of Animal Sciences 2 New Mexico State University, Las Cruces, NM Department of Animal Sciences, The University of Arizona Introduction Early embryonic loss in the mare can be caused by a lack of maternal inhibition of prostaglandin F2α (PGF2α) or increased secretion of PGF2α due to uterine inflammation. Supplementation with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) has been shown to decrease PGF2α release [1]. In this study, our objectives were to determine arachidonic acid (AA), EPA, and DHA uptake in equine endometrial explants and to evaluate their influence on PGF2α secretion and expression of enzymes involved in prostaglandin synthesis. Materials and Methods In experiment one, two endometrial biopsies from 4 mares were collected on d 2 of estrus. Biopsies were minced and equally divided into 5 wells (35 mm) and incubated in Hams F-12/MEM media for 90 min at 37ºC in a humidified atmosphere with 5% CO2. Rinsed explants were placed in one of the following treatments: control (serum free media) or 100 µm AA, EPA or DHA. After 24 h of culture, explants were stored at -80ºC until analysis of fatty acid (FA) uptake was performed using gas liquid chromatography. For experiment two, four endometrial biopsies taken from 8 mares were divided into 24 sections and plated into individual wells on multiple plates. Each of four wells on a plate received one of the following treatments in 2.5 ml of serum free media: control (no treatment), 100 µm AA, 100 µm EPA, or 100 µm DHA. Explants were then incubated for 24 h to allow for FA uptake. Following incubation, 2 plates served as control and received no stimulant, 2 plates were stimulated with oxytocin (250 nm), and 2 plates were stimulated with lipopolysaccaride (LPS, 1 µg/ml). Media was collected at 6 h and stored at -80ºC until PGF2α analysis using EIA kits (Cayman Chemical Co., Ann Arbor, MI). The relative expression of cyclooxygenase-1 and 2 (Cox-1 and 2), prostaglandin F synthase (PGFS), prostaglandin E synthase (PGES), and phospholipase A2 (PLA2) mrna transcripts were measured by quantitative real-time PCR. Threshold cycles were normalized to a reference gene (ribosomal protein S15) using the comparative Δ Ct method and fold changes (ΔΔ Ct) were determined as previously described [2]. The effects of treatment, time, stimulant and their interactions on PGF2α concentrations were analyzed using the PROC MIXED procedure of SAS [3]. Mare was considered random for all experiments. Results Prostaglandin F2α concentrations were higher (P < ) in explants challenged with oxytocin or LPS as compared to controls despite FA addition (Figure 1). Moreover, oxytocin stimulated explants to a greater (P < 0.007) extent than LPS. Endometrial explants incorporated EPA (P < 0.05) and DHA (P < 0.01) and tended (P < 0.06) to uptake AA. When explants were stimulated with oxytocin or LPS, DHA inhibited (P < ) PGF2α secretion, whereas AA and EPA failed to influence PGF2α secretion. Oxytocin increased (P < 0.02) expression of Cox-1, Cox-2, PGES, and PLA2 as compared to controls regardless of FA treatment. Similarly, LPS increased (P < 0.03) expression of Cox-2, PGFS, PGES, and PLA2. Producer s Update and Research Highlights

52 Figure 1. PGF2α concentrations (±s.e.m.) in endometrial explants in response to stimulus with LPS or oxytocin after 24 h of culture with PUFAs. x,ymeans with different superscripts differ within stimulant (P < ). a,b,cmeans with different superscript differ within fatty acid treatment (P < ). Discussion Herein, we report oxytocin stimulated PGF2α release from endometrial explants is due to an up-regulation of Cox-1 and 2, PGES, and PLA2 expression. The up-regulation of Cox-2 is similar to reports in the porcine [4] and equine [5]. For the first time we have shown LPS stimulates PGF2α release from explants through up-regulation of Cox-2, PGFS, PGES, and PLA2. Supplementation with DHA or EPA has been shown to decrease PGF2α secretion [1], whereas AA has been shown to increase release of PGF2α [1,6]. In this study, DHA inhibited PGF2α release, although EPA and AA had no influence. Inhibition of PGF2α by DHA was not due to down regulation of enzyme expression which is similar to that reported for bovine endometrial tissue[1].differences in these studies may be attributed to cell type and/or culture conditions. In conclusion, up-regulation of gene expression is one mechanism for oxytocin and LPS stimulated PGF2α release. Inhibition by DHA is through another mechanism other than down regulation of gene expression. Key Words Equine explant, PUFA, oxytocin, LPS, PGF2α References [1] Mattos R, Guzeloglu A, Badinga L, Staples C, Thatcher WW. Polyunsaturated fatty acids and bovine interferon-τ modify phorbol ester-induced secretion of prostaglandin F2α and expression of prostaglandin endoperoxide sythanse-2 and Phospholipase-A2 in bovine endometrial cells. Biol Repro 2003;69: [2] Livak KJ and Schmittgen TD. Analysis of relative gene expression data using real-time quantitative PCR and the 2-ΔΔCt method. Methods 2001; 25: Producer s Update and Research Highlights

53 [3] SAS Software. Version SAS Institute Inc., Cary, NC, USA. [4] Franczak A, Kotwica G, Kurwicka B, Oponowicz A, Woclawek-Potocka I, Petroff BK. Expression of enzymes of cyclooxygenase pathway and secretion of prostaglandin E2 and F2α by porcine myometrium during luteolysis and early pregnancy. Theriogenology 2006;66: [5] Ealy AL, Eroh ML, Sharp III DC. Prostaglandin H synthase type 2 is differentially expressed in endometrium based on pregnancy status in pony mares and responds to oxytocin and conceptus secretions in explant culture. Anim Reprod Sci 2010;117: [6] King SS and Evans WE. Effects of arachidonic acid and oxytocin on equine endometrial PGF2α during normal cycles and pseudopregnancy. Theriogenology 1987;7: Producer s Update and Research Highlights

54 Oxytocin Stimulated Release of PGF2α and its Inhibition by Indomethacin and Atosiban During Culture of Equine Endometrial Explants Leah V Penrod, Michelle L Rhoads, Sean W Limesand and Mark J Arns The University of Arizona, Department of Animal Sciences Introduction Oxytocin binds to endometrial cell receptors to activate prostaglandin synthesis. Atosiban, an oxytocin receptor antagonist, blocks oxytocin binding by preventing second messenger formation [1]. Cyclooxygenase-1 and 2 (Cox-1 and 2) are responsible for converting arachidonic acid into prostaglandin H2 which is further reduced into PGF2 α. Indomethacin blocks Cox-1 and 2 and prevents PGF2α production. The purpose of this study was to determine the effects of oxytocin stimulation over time and evaluate the effects of Atosiban and Indomethacin on PGF2α production from equine endometrial explants. Materials and Methods In experiment one, 1 endometrial biopsy from each of 10 mares of light horse breeding was harvested on d 2 of estrus by standard procedures. Biopsies were minced into 6 equal sections and placed in 35 mm wells and covered with 3 ml of a Hams F-12/MEM media. Explants were incubated 90 min at 37ºC in a humidified atmosphere with 5% CO2. Explants were washed and each well received 3 ml of fresh serum-free media. Half the wells served as controls and half were challenged with 250 nm oxytocin. Media was collected at.5, 1, 2, 6, and 24 h and stored at -80ºC until PGF2α analysis. Commercial EIA kits (Cayman Chemical Co., Ann Arbor, MI) were used according to manufacturer instructions to measure PGF2α. For experiment two, 2 endometrial biopsies were taken from each of 5 mares as described above. Biopsies were minced into 10 equal sections and plated into 10 single wells. Two wells served as controls and received 3 ml of serum free media, while the remaining pair received either serum free media (3 ml) containing 4 or 8 µg/ml of Indomethacin, 50 or 100 µg/ml of Atosiban. Following 30 min of culture, one well served as a control and one received 250 nm of oxytocin. Media was collected at 6 h and stored as described above. Data were analyzed using the PROC MIXED procedure of SAS [2]. Treatments, time, inhibitor and their interactions were considered the independent variables. Mare was considered random for all experiments. Results When endometrial explants were challenged with oxytocin, PGF2α concentrations were higher (P < ) at each time point over the 24 h culture as compared to controls (Figure 1). In both challenged and unchallenged explants, PGF2α concentrations did not increase through 2 h, and then increased (P < 0.001) at 6 and 24 h, respectively. In experiment two, concentrations of PGF2α were higher (P < 0.02) in explant cultures challenged with oxytocin as compared to controls (Figure 2). Moreover, oxytocin failed (P < 0.001) to elicit PGF2α release in explants cultured with either inhibitor. 54 Producer s Update and Research Highlights

55 Figure 2. PGF2α concentrations (+ s.e.m) in response to oxytocin after 6 h of culture with increasing concentrations of Indomethacin (Ind) or Atosiban (Ato). a,bmeans with different superscripts differ (P < 0.02). Figure 1. Prostaglandin F2α concentrations (+ s.e.m) in equine endometrial explant cultures during 24 h of culture in the absence or presence of oxytocin. x,ymeans differ within each time point for -Oxy versus +Oxy (P < ). a,b,cmeans with different superscripts differ within each treatment (P < ). Producer s Update and Research Highlights

56 Discussion Equine endometrial explants responded to oxytocin during culture and is similar to previous reports [3,4]. The oxytocin-stimulated release of PGF2α reported here involves oxytocin binding to a receptor that initiates the prostaglandin synthesis cascade as demonstrated by the block of PGF2α release in the presence of Atosiban. This inhibition is similar to that seen in vitro studies using oxytocin-stimulated myometrial strips from non-pregnant [1] and pregnant women [1,5]. Indomethacin equally blocked PGF2α secretion in oxytocin-stimulated equine endometrial explants. This inhibition is similar to what King and Evans [3] found in equine endometrial explants. This further confirms PGF2α is being produced through the prostaglandin synthesis cascade and not through an alternative pathway. Conclusion In conclusion, these data confirm that equine endometrial explants can be stimulated with oxytocin to secrete PGF2α; this release can be inhibited both through an oxytocin receptor antagonist and a Cox inhibitor. These data elucidate further the inflammatory response and provide an in vitro system to evaluate factors that can modulate the uterine inflammatory response. Key Words equine endometrial explant, oxytocin, PGF2α, atosiban, indomethacin Literature Cited [1] Phaneuf S, Asboth G, MacKenzie IZ, Melin P, Bernal AL. Effect of oxytocin antagonists on the activation of human myometrium in vitro: Atosiban prevents oxytocin-induced desensitization. Am J Obstet Gynecol 1994;171: [2] SAS Software. Version SAS Institute Inc., Cary, NC, USA. [3] King SS and Evans WE. Effects of arachidonic acid and oxytocin on equine endometrial PGF2 alpha during normal cycles and pseudopregnancy. Theriogenology 1987;7: [4] Watson ED, Aubrey ES, Zanecosky HG, Sertich PL. Isolation and culture of glandular epithelial and stromal cells from the endometrium of mares. J Reprod Fert 1992;95: [5] Buscher U, Chen FC, Riesenkampff E, Dehn DV, David M, Dudenhausen JW. Effects of oxytocin receptor rntagonist Atosiban on pregnant myometrium In Vitro. Obstet & Gynecol 2001;8: Producer s Update and Research Highlights

57 Elevated Catecholamines are the Predominant Inhibitors of Insulin Secretion and Contribute to Altered Metabolic Phenotype During Acute Hypoxemia in Fetal Sheep Dustin T Yates 1, Abigail L Fowden 2, Anthony R Macko 1, Xiaochaun Chen 1, Alice S Green 1 and Sean W Limesand 1 1 The University of Arizona, Tucson, Arizona 2 University of Cambridge, Cambridge, United Kingdom Department of Animal Sciences, The University of Arizona Elevated fetal stress hormones during hypoxemia are associated with suppressed insulin secretion and altered metabolism. When fetal hypoxemia is chronic, these alterations persist after birth and result in poor growth and carcass quality. Our objective was to determine if preventing catecholamine secretion via adrenal demedullation fully or partially relieves suppression of insulin secretion and alteration of the metabolic phenotype during acute fetal hypoxemia, which was induced by bleeding nitrogen into the ewe s trachea. At 123 days of gestation (dga; term 147), bilateral demedullation (AD; n = 4; verified by chromogranin-a immunostaining) or sham (controls; n = 5) operations were performed on sheep fetuses along with vascular catheterization. Two square-wave hyperglycemic clamps were performed at 128 dga to measure glucose stimulated insulin secretion (GSIS) during normoxemic (26.2 ± 1.0 mmhg) or hypoxemic (14.3 ± 0.4 mmhg) conditions. A subsequent hypoxemic challenge at 134 dga was performed to test adrenal gland responsiveness. Plasma norepinephrine, epinephrine, and cortisol concentrations were increased (P < 0.05) by 6.5-, 30-, and 4.2-fold, respectively, in controls subjected to hypoxemia at 128 dga and by 12.5-, , and 15- fold at 134 dga, showing increased (P < 0.05) responsiveness to hypoxemia. No changes due to hypoxemia occurred in AD fetuses at either age. During GSIS, insulin concentrations increased (P < 0.05) 3-fold in normoxemic controls and over 2-fold in AD fetuses in response to hyperglycemia. Hypoxemia blocked the insulin response to increased glucose in shams, but AD fetuses responded as they had during normoxemia. Despite the absence of elevated catecholamines, lactate increased during hypoxemia (P < 0.05) in AD fetuses (1.8 ± 0.2 vs. 7.1 ± 0.4 mmol/l), though to a lesser extent than in controls (2.4 ± 0.1 vs ± 1.4), while glucose was not altered in either treatment. These findings indicate that anaerobic metabolism may initiate at the onset of hypoxemia, and that this change is likely mediated jointly by catecholamines and other regulating factors. These data show that elevated catecholamines are the principal inhibitors of GSIS during acute fetal hypoxemia but are only partially responsible for the altered metabolic phenotype, including hyperlactacemia. Additionally, increased basal concentrations of stress hormones and increased adrenal responsiveness to acute hypoxemia during the final stages of gestation may further impact fetal metabolism. Though acute hypoxemia elicits a similar metabolic phenotype as chronic hypoxemia, changes during the former are not permanent and likely do not affect growth performance and carcass quality in offspring. Producer s Update and Research Highlights

58 Honors College Research Grant Project Sarah Klopatek The University of Arizona, Department of Animal Sciences Sarah Klopatek, an Animal Sciences undergraduate student, was recently awarded a $1300 research grant from the University of Arizona Honors College. Sarah will work with Dr. Sean Limesand at the ARC Research Center. Upon completion of this research project data will be published in the Honors College annual publication The Spirit of Inquiry. Further Ms. Klopatek will present her data in the Research Expo which is held in February, Project Title: Vascularity and ß-cell Density of Pancreas in Growth Restricted Sheep Background: Poor diet and a sedentary lifestyle have long been known to contribute to the development of diabetes overtime. However, multiple epidemiological studies in human populations, as well as in animal models, clearly demonstrate that the impairments of the biological functions that lead to diabetes may begin in utero. The placenta is a temporary organ that is present only during pregnancy and serves to transport oxygen and nutrients to the developing fetus. Several factors such as, malnutrition, infection, and maternal and fetal genetics can cause placental insufficiency, a condition which complicates 10% of all pregnancies and results in impaired delivery of oxygen and nutrients to the developing fetus. This, in turn is the leading cause of intrauterine growth restriction. When the fetus does not receive adequate nutrients, especially during the third trimester, when rapid fetal growth normally occurs, its organs develop abnormally. One such organ, the pancreas, which contains the insulin secreting ß-cells, has been shown to be reduced in size as well as the number of ß-cells it contains in growth-restricted fetal sheep, an animal model used to extensively study several aspects of human fetal development. Project Objective and Outline: The objective of the proposed research will be to investigate/measure the number and quality of the blood vessels that supply the ß-cells in normal and growth-restricted sheep fetuses. This work is pertinent in understanding the factors that contribute to early development of ß-cell failure leading to diabetes as well as identifying specific targets for future treatments to prevent the onset of this disease. To be utilized in the proposed experiment, pancreas specimens from both normal and growth-restricted fetal sheep, have been collected, frozen and stored at the Agricultural Research Complex at the University of Arizona. These specimens will be sliced into very thin sections, mounted to glass microscope slides, and labeled with immunoflourescent dyes to identify ß-cells and blood vessel cells. Flourescent images depicting the relationships between the ß-cells and their supplying blood vessels will be acquired. The images will be analyzed to determine whether the density of blood vessels supplying the ß-cells is adversely affected in growth-restricted fetal sheep. It is postulated that this data will demonstrate that vascularity along with ß-cell density will decrease in growth restricted sheep. The data collected from this experiment describing the relationship between vascularity and ß-cell density will advance the understanding of fetal development, and may contribute to the design of future clinical therapies to improve pre-natal care and prevent the early onset of diabetes. 58 Producer s Update and Research Highlights

59 Comparison of Feedlot Performance and Carcass Merit of Various Crossbred Cattle Samuel R Garcia 1, John A Marchello 1, Hamdi A Ahmad 1 and Russell Tronstad 2 1 The University of Arizona, Department of Animal Sciences 2 The University of Arizona, Department of Agricultural and Resource Economics For many years, the utilization of the British cattle breeds (eg. Angus, Shorthorns, and Hereford) was the standard for the American beef producer. These types of cattle proved to provide quality carcasses equaling palatability for the consumer. However, there was one major disadvantage associated with these carcasses; they had excessive subcutaneous and intermuscular fat. This proved to be an issue for the packer and the consumer; the subcutaneous fat had to be trimmed. This becomes a loss for the packer because it diminished the total pounds of saleable product and excess fat also causes the meat to be less desirable and palatable to the consumer. In an effort to improve yield grades, the U.S beef industry initiated the use of crossbreeding system. In today s feedlots, this trend can be observed, as the majority of the cattle on feed are crossbred cattle or Holsteins. In today s beef market the main consideration is how to have the highest quality carcass (Quality grade choice with a yield grade 2 ) with the least amount of investment (time and capital). Achieving this goal is important to the producer and consumer alike and therefore the evaluation of traits that crossbred calves yield is necessary to optimize production. In this study, Waguli steers were compared to Wagyu x CGC, Hereford x Tuli and the Brangus breeds comparing feedlot performance and carcass merit. The overall objective of this study is to obtain a comparison of the Waguli breeds feedlot performance and carcass traits to other crossbred breeds. MATERIALS AND METHODS Feedlot Performance All procedures involving animal care and management were approved by the University of Arizona Institutional Animal Care and Use Committee (IACUC; No ). A total of 18 steers were obtained from the U of A V-V ranch. The breakdown of the steers was as follows: 6 Waguli, 6 Wagyu x CGC, and 6 Hereford x Tuli. The steers traveled 203 miles and were received at the University of Arizona Feedlot on October 19, A second lot of steers, 8 Brangus steers from La Playa Ranch in Sonora, Mexico, (177 miles) was received on the 14th of January Steers were started on high quality alfalfa hay for the first 7 days of the trial. On day 8, the steers received 70% concentrate diet increasing the concentrate percentage until 90% concentrate was reached. Steam flaked corn was fed as the energy/carbohydrate source and alfalfa hay as the roughage source. Also included in the diet was, molasses, soybean meal, mineral premix, Rumensin/Tylan and urea (Table 1). The feed bunk was managed by the slick bunk approach. The slick bunk approach is designed so the animals finish the feed ~1 hour before the next feeding time. The bunk was evaluated at 0800 daily and then the amount of feed to be offered was determined. Total pounds of feed consumed were recorded daily, along with the feed cost. Producer s Update and Research Highlights

60 Steers were weighed upon arrival to the feedlot and every 28 days thereafter. Fat thickness measurements were obtained by using an ultrasound. Ultrasound readings were initiated once steers reached 900 lbs. and every 28 days until desired back fat thickness was reached. Steers were harvested when back fat at the 12th rib reached 1 cm. Steers that did not reach 1cm backfat were harvested when weight gain reached a plateau. Boleman suggest that the optimum steer should possess sufficient marbling (0.4 of backfat opposite the ribeye) and still maintain a yield grade in the range (1998). Harvesting Method All steers were harvested at the University of Arizona Meat Science Laboratory. The Carcasses were dry aged for 14 days at 35 F with around 80% humidity. Carcass Merit On the 15th day, carcasses were ribbed between the 12th and 13th rib. The following data: maturity score, marbling score, color of lean, firmness and texture scores were be obtained and recorded. The data collected were used to determine the quality grade for each carcass. Yield grade was figured by using a formula that combines the following factors: hot carcass weight, ribeye area, percent of kidney, pelvic and heart fat and 12th rib fat thickness. Evaluation of tenderness was determined by shear force values. Shear force values were generated using a Warner-Bratzler Shear Force machine. A 12th rib steak measuring 1 in was cooked on an electric grill to an internal temperature of 160 F and chilled to 72 F after cooking. Ten cores parallel to the muscle fiber, measuring.5 in, were taken from the each steak and sheared perpendicular to the muscle fibers using a Warner-Bratzler Shear Force Machine Using ten cores, the highest and lowest values were eliminated and the remaining eight were averaged to determine tenderness value for each steer. Cost to gain, feed per pound of gain, and average daily gain were calculated for the every 28 day period and averaged among the breeds. RESULTS Feedlot Performance All steers started at an average initial weight of 370lbs. However, the Brangus steers started at a later date, but entered the trial at a heavier weight (515) and therefore weights among all four breeds remained similar. There was a significant difference (P<0.05) between Brangus and the rest of the breeds when considering initial weight. This was taken into account in the statistical analysis. Average daily gains were similar for Waguli ADG = 2.11lbs; Wagyu x CGC ADG= 2.53 lbs; Hereford x Tuli ADG= 2.46 lbs; Brangus ADG =2.89lbs; however, there was a significant difference (P<0.05) between Brangus and Waguli. Feed to gain conversion was as follows: Waguli F:G= 7.85lbs; Wagyu x CGC F:G= 7.01 lbs; Hereford x Tuli F:G=6.14; Brangus F:G= 7.12lbs; a significant difference (P<0.05) was observed only between 60 Producer s Update and Research Highlights

61 Hereford x Tuli. Final weights were as follows: Waguli -985lbs; Wagyu x CGC lbs; Hereford x Tuli 994 lbs; Brangus lbs; a significant difference (P<0.05) was observed between the Wagyu x CGC cross and the other crosses (Table 2). Carcasses were electrically stimulated and dry aged, as noted in the materials and methods. Dressing percentage ( DP) was calculated on HCW and the results were Waguli -58%; Wagyu x CGC -57%; Hereford x Tuli -60%; Brangus -59%; no significant difference (P<0.05) was observed for DP. No significant difference (P<0.05) was noted between breed for quality grade(qg), the quality grades were Waguli -Choice 30; Wagyu x CGC -Choice 25;Hereford x Tuli -Choice 20; Brangus -Choice 40. Ribeye area (REA) was exceptional for all breed, REA for the Waguli in² and 1.94 in²/cwt ; Wagyu x CGC in² and 2.0 in²/cwt; Hereford x Tuli in² and 1.94in²/cwt; Brangus -11.9in² and 1.99in²/cwt; showing a significant difference (P<0.05) between Wagyu x CGC and Hereford x Tuli and Waguli. Yield grade (YG) were desirable for all breeds and no significant differences (P<0.05) were noted, YG was Waguli -2.48; Wagyu x CGC -2.53; Hereford x Tuli -2.97; Brangus Tenderness was evaluated by pound of force need to shear a ½ core of a rib steak and the results were as follows: Waguli = 5.97 lbs.; Wagyu x CGC= 6.71 lbs; Hereford x Tuli=5.35 lbs; Brangus=5.28 lbs; there was a significant difference (P<0.05) between Wagyu x CGC and the rest of the breeds (Table. 3). For shear values of less than 7, the steaks are considered very tender. DISCUSSION Average Daily Gain In the present study, the average ADG of the Brangus steers was higher than the Wagyu x CGC, Hereford x Tuli, and the Waguli groups. This supports the findings of Casas et al. (2010), who found that the when a Brangus was used as a grandsire, the offspring had higher growth rates. Adding to this Huffman and associates (1990), found that Brahman crossbreds spent less time in the feedlot versus Angus and Angus crossbreds. This study proved interesting in that the Wagyu x CGC cross ranked among the top when measuring ADG. Radnuz et al.(2009) found that Wagyu-sired steers had both lower ADG and DMI when compared to Angus sired steers. However, in this trial, the Wagyu was crossed with other breeds that have higher growth characteristic which is the justification for the results. Additionally, the Waguli breed had the lowest ADG. This is similar to a study done comparing Wagyu- and Angus- Producer s Update and Research Highlights

62 sired calves in which it was determined that the Wagyu had a slower rate of gain leading to decreased daily intake and more days on feed (Radnuz et al., 2009). The Hereford x Tuli cross showed not to stand out when looking at ADG. Although the Hereford breed is known to have better gains (Huffman et al., 1990), the Tuli influence which has the characteristic of early maturing and moderate frame may have decreased the ADG. Feed to Gain Although the Hereford x Tuli cross didn t prove to excel in gain, this pen of steers proved to be the most efficient in feed conversion. This agrees with the findings of Butler et al. (1962) who found when comparing Herefords to other British breeds that they demonstrated higher efficiency. However, it opposes some findings in which Herefords were not more efficient in feed utilization and didn t gain more (Kappel et al., 1972). The Wagyu x CGC had the second most efficient use of feed, which may provide evidence that a crossbreeding system does highlight the positive aspects of each breed being used. This supported the findings of Radnuz et al. (2009), who showed that Wagyu cattle display a higher gain to feed ratio when compared to the British breeds. The Brangus and the Waguli groups exhibited less efficient utilization of feed. This is conflicting to the results of Huffman et al. (1990), who found that when a crossbreeding system utilizes the Zebu influence feedlot performance is improved. Dressing Percentage As previously stated the Hereford x Tuli cross group had the highest average DP followed by the Brangus, Wagyu x CGC, and the Waguli. The difference among the breeds was relatively small and not significant. These findings disagree with research conducted by Butler et al. (1962) and Casas et al. (2010), where they observed that when the Hereford was compared with other breeds (Angus and Brangus) they dressed lower. In the same study by Casas and associates (2010) they found, the Brangus had the highest dressing percentage. In the present study the Hereford x Tuli group dressed the highest. Quality Grade The results of the QG evaluation were somewhat distorted from previous research. Although in all groups carcasses were all classified as Choice grade, the Brangus breed had the highest Choice grade followed by the Waguli, Wagyu x CGC, and lastly the Hereford x Tuli cross. The anticipated results were that the two crosses that have Wagyu influence would have the highest QG; however, the results that were observed may be an insight to what occurs with crossbreeding. It has been shown by Ibrahim et al. (2008)., that the Wagyu is more likely to grade Choice when compared to other British breeds and that the Waguli has a higher QG than Brahman cattle. Results show that the influence of the British breed (e.g. Angus) took over in this British x Zebu cross. The fact that the Hereford x Tuli cross group had the average lowest QG supports other findings showing that Angus or Angus crosses tend to outperform Herefords regarding carcass merit (Casas et al., 2010). Yield Grade In this trial the YG results continued from lowest to highest as follows: Wagyu x CGC, Brangus, and Hereford x Tuli. The differences were not significant but relatively expected as the British influence would increase YG. The present results support the finding of Casas et al.(2010) study finding that Brangus cattle had lower YG grades than Hereford cattle. Ribeye Area and Ribeye Area per Hundred Weight The breeds greatly varied between LM area and LM area per hundredweight. When looking LM area the Waygu x CGC cross had the largest followed by the Brangus, Hereford x Tuli cross and lastly the Waguli. Wagyu x CGC had the largest frame size and carcass and the Wagyu influence along with the CGC composite influenced LM greatly. The Brangus group proved interesting to have the second largest LM area, as it has been shown by Ibrahim and colleagues (2008) that the more Brahman ancestry the smaller the size of the LM area. Waguli have never been shown to have a 62 Producer s Update and Research Highlights

63 large LM area and therefore the results were as expected for this breed. When comparing the LM area per hundred weight, one of the main consideration is the weight of the carcass. In this data section, the Wagyu x CGC was the largest followed by the Brangus, Waguli and the Hereford x Tuli. These results correlates with what was found by Radnuz et al.(2009), in which the Wagyu proved to have a larger LM area than the British breeds. The other breeds were more moderately sized and thus the data was more favorable for their average LM area per hundred weight. Shear Force Value As explained in the Material and Methods section, the SFV translates into the tenderness factor of the carcass. Again the Brangus had the lowest SFV or in other words was the most tender. The results are indicative of the influence of British cattle, which tend to be more tender because of their ability to marble. It is thought that the Brangus outperformed the Hereford cross because of the Angus influence. This is supported by research completed by Butler and associates, in which they compared the carcass merit of the Angus to the Herefords and found that the SFV was lower for the Angus steers (1962). The results of the present trial were contradictive to research published on the Wagyu, as they have been shown to be used in crossbreeding systems to actually lower or improve SFV of other breeds (Radnuz et al., 2009). CONCLUSION This study demonstrated the various outcomes that occur when using a crossbreeding system. It showed that both feedlot performance and carcass merit can vary between breed and even between contemporaries. This research indicates that the selection of a breed for any operation depends on several factors ( environment, objection of operation, etc) and therefore overall success of feedlot performance and carcass merit is dependent on a combination of factors not just a consequence of breed. REFERENCES Adams, N.J., G.C. Smith, and Z.L. Carpenter. Carcass and Palatability Characteristics of Hereford Crossbred Steers. J Anim Sci. 1977; 45: American Meat Science Association Research Guidelines for Cookery, Sensory Evaluation and Instrumental Tenderness Measurements of Fresh Meat. Am. Meat Sci. Assoc., Chicago, IL Brewer S, Novakofski J. Consumer sensory evaluations of aging effects on beef quality. J Food Sci. 2008;73(1):S Brooks JC, Belew JB, Griffin DB, et al. National Beef Tenderness Survey J Anim Sci 2000;78(7): Butler, O.D., T.C. Cartwright, L.E. Kunkle, F. A. Orts, G.T. King, and D.W. Lewter. Comparative Feedlots Performance and Carcass Characteristics of Hereford and Angus Steers. J Anim Sci.1962; 21: Casas,E., R.M. Thallman, L.A. Kueln., L.V. Cundiff. Postweaning Growth and Carcass Traits in Crossbred Cattle from Hereford, Angus, Brangus, Beefmaster, Bonsamara and Romosinuano Maternal Grandsires. J Anim Sci. 2010; 88: Epley R.J.. Aging Beef. Minnesota Extension Service; University of Minnesota Gruber, S. L., J. D. Tatum, J. A. Scanga, P. L. Chapman, G. C. Smith, and K. E. Belk Effects of postmortem aging and USDA quality grade on Warner-Bratzler shear force values of seventeen individual beef muscles. J. Anim. Sci. 84: Herring AD, Sanders JO, Knutson RE, et al. Evaluation of F1 calves sired by Brahman, Boran, and Tuli bulls for birth, growth, size, and carcass characteristics. J Anim Sci. 1996; 74(5): Huffman, R.D., S.E. Williams, D.D. Hargrove, D.D. Johnson, and T.T. Marshall. Effects of Percentage Brahman and Angus Breeding, Age, Season of Feeding and Slaughter End-point on Feedlot Performance and Carcass Characteristics. J Producer s Update and Research Highlights

64 Anim Sci. 1990; 68: Ibrahim RM, Goll DE, Marchello JA, et al. Effect of two dietary concentrate levels on tenderness, calpain and calpastatin activities, and carcass merit in Waguli and Brahman steers. J Anim Sci 2008; 86(6): Kappel, L.C., F. G. Hembry, P.E. Humes, P.E. Schilling, and R.H. Kleit. Climatic, Breed, and Ration Effectson Feedlot Performance and Carcass Characteristics of Steers. J Anim Sci. 1972; 35: Radunz, A.E., S.C. Loerch, G.D. Lowe, F.L Fluharty, and H.N. Zerby. Effect of Waygu- versus Angus- Sired Calves on Feedlot Performance, Carcass Characteristics and Tenderness. J Anim Sci. 2009; 87: Roeber D.L., Cannell R.C., Belk K.E., et al. Effects of a unique application of electrical stimulation on tenderness, color, and quality attributes of the beef longissimus muscle. J Anim Sci 2000;78(6): Sherbeck, J.A., J.D. Tatum., T.G.Field., J.B. Morgan., and G.C. Smit. Feedlot Performance, Carcass Traits and Palatability Traits of Hereford and Hereford x Brahman Steers. J Anim Sci. 1995; 73: Standardized Warner-Bratzler Shear Force Procedures for Genetic Evaluation. Texas A and M University < [ 28 Nov. 2010]. Breeds of Livestock. Oklahoma State University [10 Nov 2010] 64 Producer s Update and Research Highlights

65 Elevated Catecholamines are the Predominant Inhibitors of Insulin Dry and Wet Aging Effects on Tenderness, Palatability and Oxidative Rancidity in Beef Steaks Tiffany J Hebb The University of Arizona, Department of Animal Sciences Department of Animal Sciences, The University of Arizona ABSTRACT Red meat, especially beef, is exploring new ways to market product in order to maintain a competitive edge. One resolution to maintain competitiveness is to improve and understand more about palatability characteristics of beef because it is known that palatability greatly influences future purchase. The objective of the present study was to determine the effects of dry aging and wet aging, common aging techniques in the meat industry, on tenderness, wholesomeness, and consumer perception of beef steaks. Beef steaks were separated into wet aging and dry aging treatments and aged for 14 days. Samples were taken on day 7 and 14 to compare and evaluate oxidative rancidity and shear force value for the two treatments. Sensory analysis from consumers was also conducted to gauge palatability characteristic differences between dry and wet aged steaks. Under the conditions of this study, dry and wet aged steaks were not statistically different in regards to average shear force value and oxidative rancidity (P>0.05); however, aging period effect on shear force showed a significant difference (P<0.05). The study also found that in the sensory portion of this project, tenderness was statistically different between wet and dry aged steaks (P<0.05) where wet aged steaks were more tender; however, juiciness, flavor intensity, and acceptance showed no statistical difference (P>0.05). Wet and dry age production cost is also estimated to compare cost analysis. INTRODUCTION The meat industry has progressed in the variation of meat products it offers. Non-red meats, such as poultry, sell a variety of product options such as deli meats, ready to eat convenience food and the general fresh cuts. On the other hand, red meat, especially beef, is exploring new ways to market to consumers in order to maintain a competitive edge. One resolution to maintain competitiveness was to improve and understand more about palatability characteristics of beef. It is known that palatability is the primary factor influencing consumer purchase decisions of beef. One way to improve palatability is through aging which is the primary way beef is processed to reach its optimum palatability characteristics, especially tenderness. Wet aging and dry aging are two different aging methods used in beef processing today, even though; wet aging is the most widely used. Consumers have suggested that there is a difference in flavor, tenderness and other characteristics that distinguishes wet aged fresh beef from dry aged fresh beef. Consumers make claims that dry aged beef tend to have a beefy, brown roasted flavoring, while wet aged beef tend to have a bloody/serumy and metallic flavoring (Campbell et. al., 2001; Warren & Kastner, 1992). To accommodate consumers request, processors are increasing dry aged fresh beef cuts. Due to increase demand; processors and retails are more interested in understanding the technique because it may be a revamped way to market beef. Despite the lack of scientific evidence to support any differences in eating quality, dry aged beef steak is marketed as premium quality beef at gourmets and upscale restaurants (Smith et. al., 2008). In fact, the research available has shown Producer s Update and Research Highlights

66 that there is no significant difference (P<0.05) between the two with regard to flavor (Parrish et al 1991; Laster 2008; Smith et al 2008; Sitz et al. 2006). Consequently, more effort intended to understand the perceived differences between wet and dry aging as well as science based measure of wholesomeness and quality are needed. The information gathered regarding the two techniques could facilitate marketability of dry aging beef to its counterpart which would be beneficial to the viability of the meat industry. The objective of the present study is to determine the effects of the aging techniques, dry and wet, on tenderness, wholesomeness, and consumer perception beef steaks. This study addressed the differences, if any, between dry aged and wet aged beef steak, by evaluating and comparing palatability characteristics, Warner-Bratzler shear force values and oxidative rancidity values over a period of 14 days. In part, the study served as broad analysis of the difference of the two techniques and possibly a foundation to build upon for marketing dry aged beef on a larger scale to consumers. BEEF MARKETING Both wet aging and dry aging provides a way to further brand beef which has historically been considered a generic product. Generic in a sense that it is not branded with a guarantee of any desirable attributes. Some blame the generic appeal of beef for the documented decrease in demand during the 1980s and 1990s because consumers could not distinguish desirable value in beef (Purcell and Lusk 2003). Currently, the United States total beef consumption has decreased from 28.1 billion pounds in 2007 to 26.9 billion pounds in 2009 (USDA ERS 2010). While many factors can contribute to the decrease in total consumption, some decrease may be partly due to the inability to provide guaranteed desirable characteristics. The generic brand may not prove to be worth the price on the retail level. Today, marketing of any food item requires distinction between products. Common practice for meat is to differentiate meat products by brands and labels that identify desirable attributes, in return, increase profitability for the meat industry (Purcell and Lusk, 2003). Studies have demonstrated that developing a link between consumer s desires and a brand or new product brand provides successful marketing as well as continues to revitalize demand for beef (Purcell and Lusk, 2003). Studies by Lusk et al. and Lusk and Schroeder as noted by Purcell and Lusk, 2003 using experimental auctions and stimulated retail environment tested consumer purchase based on different labeled attributed of beef rib eye steaks priced $7.50/ lb. Figure 1 illustrate the results in which 52% consumers purchased Certified Angus labeled steak, followed by 19% USDA Choice, 15.5% did not to purchase any steak, 7.5% guaranteed tender labeled, 6% natural steak, 0% chose generic unlabeled steak. Also in the same study, consumers were given an unlabeled generic steak and were given opportunity to bid in auction to exchange their steak with the four types mentioned previously. Figure 2 summarizes the results of the study as noted by Purcell and Lusk 2003 which reports the median and average premium over that of unlabeled generic steaks. 66 Producer s Update and Research Highlights

67 Certified Angus Beef label averaged $3.29, USDA Choice label averaged $2.27, Natural average $1.10 and Guaranteed Tender averaged $1.54 over unlabeled generic beef. If aging, especially dry aging, is commercialized it may possibly add more revenue for the beef industry especially if consumers consider this product to be more tender or flavorful than wet aging. As Figure 2 demonstrates, consumers are willing to pay a premium for beef that has desirable attributes. Aging meat is not a new concept. It has been used in the meat processing since colonial America. The technique and science of the method however has developed to be more sophisticated process. BACKGROUND OF POST MORTEM AGING During the colonial period, early settlers had limited resources in which to extend the life of food because refrigeration was nonexistent. Depending on the region, colonist in the north used the colder months to freeze food while colonists in other regions, such as the south and west, used salting, pickling, smoking and drying (Oliver, 2005). Large cuts of meat were not incorporated into the diet until the 1800s so most meats were consumed same day as slaughter. The Native American in the southwest were accustomed to drying meats and referred to it as jerking and it could be done without the use of salt because of the drier climate (Oliver, 2005). Although this form of food preservation is no longer necessary as a method of preservation, it is still widely used today because it gives an appetizing flavor to foods and provides variation to the diet. As it was later realized, drying of foods used as a means for preservation could also be used to tenderize meat as well. Butchers used the drying method extensively, but as food technology advanced so did the techniques used by the food industry. This conventional method was mostly abandoned for a newer more convenient method of aging meat which required refrigeration. Refrigeration proved to be just as beneficial to tenderness of meat. Jeremiah et al. (1978) states post mortem refrigerated storage improves tenderness of beef. Currently post-mortem aging processes are practiced commercially which is referred to as dry and wet aging. The debate as to the better aging method is Producer s Update and Research Highlights

68 still unresolved as many processors have their own perspectives of reaching a superior end result. Many processors perceive dry aging to be the superior process; conversely, others prefer wet aging. Both methods have benefits and shortcomings. The usage of one method over the other currently depends primarily on extrinsic factors such as size of facility, space, and market demand. Moreover, factors of superiority in palatability characteristics and quality are limited in scientific evidence to support either claim (Parrish et al. 1991). DRY AGING Dry aging is the ancient method of preserving fresh meat. This method was utilized for many years before advances in food technology existed. Today, it is still used but not for preservation. It is used for aging and can be defined as aging in refrigerated temperatures without any packaging. Wholesale cuts or whole carcasses are exposed to air and dried for up to 28 days to improve palatability characteristics. Although the dry aging method is different from facility to facility, the general parameters are temperature, which is acceptable from 0-4degree centigrade, days of aging and air flow or relative humidity which is acceptable at 80% (Campbell et al., 2001; Parrish 1991; Kastner; 1992). Due to the limited studies and lack of standardization pervious dry age methods can vary. The dry aging technique for beef is the preferred method by some processors over that of wet aging. The most prominent reason for this decision is flavor. Generally, over the aging period, unique distinct flavors develop. One study references the flavor as beefy and brown/roasted as well as more intense than the wet age counterpart (Warren and Kastner, 1992). According to Troy at al. (2010) the exposure to air and concentrated level of flavor precursors such as heptanes could contribute to the variance in flavor between wet and dry aging. Ultimately, the flavor gives dry aged beef its uniqueness that consumers are suggesting. The major disadvantage associated with dry aging beef is shrink loss and excessive trim waste. Being exposed to the air causes the meat to shrink which is the effect of losing moisture in the drying process. Congruently, the outer surface can become hard and sometimes moldy referred to as crust. The carcass must be trimmed of the crust before being fabricated into cuts and or sold. Trimming excess waste from the carcass is time consuming and laborious. Shrink and trim are directly a result of the dry age process. About 20 percent of the weight is lost during the process (De Geer et al., 2009). In an earlier study, Parrish et al. (1991) found that dry aged fresh beef had a greater amount of trim loss (P<0.05). In the same study by Parrish et al., (1991), inferred shrink loss in loins and ribs dry aged for 14 or 28 days to be more evident than those aged in vacuum packaged for same period of time. Another disadvantage is the labor involved. Considerable amount of time and space is needed to dry age beef (Smith et al. 2008). For small or medium processing facilities it is not feasible; it may be a determining factor in which method is used or preferred. Consequently, the considerable amount of yield loss and trim from drying explain the need to have a greater retail price than the wet aged beef, Smith (2007) suggests 16.3 to 18.8 percent greater. Some consumers could be willing to purchase dry age beef for a premium or higher price than wet age beef if it is perceived to have a greater quality (Purcell and Lusk, 2003). Despite the disadvantages of the technique, many processors still use this method generally because to assure customers of a quality product thus purchasing it at a higher price. Although there is no clear consistent scientific evidence to support the flavor differences of dry age beef, discriminating consumers suggest dry age flavor is superior. The demand for dry age beef has created enough of a market to make retailers interested in supplying this type of beef. Thus far, dry aged beef is considered a high value product sold in expensive restaurant and gourmets with a unique selling point (Troy et al., 2010). Successful distinction of consumer desirable characteristics for dry aging may allow retailer to market it on a larger scale. WET AGING 68 Producer s Update and Research Highlights

69 Wet aging is the most common form of aging done today. The method of wet aging began in the 1960 s. It is defined as storing meat in a sealed barrier package at refrigerated temperatures (Smith et. al 2008). The wet aging era flourished when advancements were made in food technology. In particular, the development of vacuum packaging and atmospheric packaging helped to facilitate the use of wet aging. Essentially, all beef in the United States is wet aged in vacuumed packaging (Smith et al., 2008). Some processors prefer the wet aging method over the dry method because of several benefits. Firstly, wet ageing takes less space. Many packing plants especially medium to small scale operations do not have much space to hold wholesale or retail cuts for extended periods of time as needed in the dry age process. This holding space can be freed with the use of vacuum packing because meat can be stacked to increase space. Wet aging fresh meats can be easily transported in a refrigerated truck to retailers because it is in a vacuum package. It is more convenient for processing facilities to use this method. Also, having the vacuum package barrier reduces microbes and any other possible cross contamination. The vacuum package provides unfavorable conditions for increase microbe production and the growth of organisms are suppressed thus shelf life stability is increased (Gill and Gill, 2005). Consequently, the low concentration of oxygen is conducive for lactic acid bacteria growth. Sometimes the exponential growth of lactic acid bacteria can result in the unpleasant odors after opening a wet aged beef package (Gill and Gill, 2005). Another benefit to wet aging is higher yields. Comparatively, wet aging produces a higher yield because it does not need to be trimmed of mold or hardening meat surfaces because moisture is retained (Smith et.al, 2007; Parrish et. al, 1991). On the contrary, there are disadvantages to using the wet aged method too. One notable shortcoming is purge. Purge loss is the excess moisture loss that results from the reduction of water holding capacity in meat. Purge will continue to be an issue in wet aging because vacuum packaging pulls moisture out of the meat by way of air pressure to maintain the vacuum seal. Meat moisture loss may have an effect on juiciness of meat. As a result, affect palatability scores and consumer acceptance of beef products. Substantial claims suggest wet aging does not lead to improvements in flavor. However, consumers suggest wet aging produce bloody serumy and metallic in meat (Campbell et. al.; Warren Kastner, 1992). Compared to its aging counterpart, dry aging, it is claimed to be less flavorful but scientific evidence does not support the claims. However, information is limited. TENDERNESS The term meat quality can be a broad perception by the consumer which can include carcass composition and conformation, eating quality of meat, health concerns and production related issues like animal welfare and environmental impact. All of these factors help to give assessment of meat quality but the most significant assessment that supports the repurchase of meat by consumers is eating quality. This is the perception that is obtained after consumption along with the views on color, nutrition and price (Boleman et.al., 1997). The primary factor that determines the perceived eating quality and taste of meat by consumers is tenderness (Huffman et al., 1996, Smith et al., 2008). A study surveying beef tenderness on consumer satisfaction showed 51 percent of consumers considered tenderness the attribute they wanted most whether at home dining or in restaurant dining (Huffman et. al., 1996). Tenderness is defined as yielding readily to force or pressure or to be easily broken (Dictonary.com unabridged 2010). According to Huffman et al (1996), identifying desirable tender of beef by consumers will allow restaurants to capitalize on desirability of beef. Producer s Update and Research Highlights

70 Techniques have been used in the industry for many years to improve tenderness of beef and other fresh meats. In fact, tenderizing meat has been done for hundreds of years before advanced butchering and slaughtering facilities existed. Today, nearly all fresh meat in the United States is aged to enhance palatability characteristics such as tenderness, flavor, color, aroma, texture, and juiciness (Smith 2008). To maximize tenderness and other palatability characteristics wet aged beef is stored in a vacuum packaged bag at refrigerated temperatures for up to 28 days (Parish, 2011). Dry aged beef is stored in refrigerated temperatures for about 3 to 5 weeks to reach optimum desirability (Troy et al., 2010). It has been noted that aging beef cuts longer than 28 days does not improve tenderness (Parish, 2011). Studies have revealed that proteolytic enzymes are responsible for the degradation of structural proteins in the muscle fibers which causes tenderness. Although it is uncertain of the exact actions, it is generally accepted that calpain-mediated degradation is integral in tenderization during the aging process (Koohmaraie, 1992, 1996; Taylor et al., 1995, Boehm et al., 1998; Wheeler et. al). Animal muscle will become tender after slaughter naturally, but the tenderization effects are short lived so post mortem aging increases tenderness in muscle (Parrish, 2011). The amount of calpain and calpastain available can depend on breed thus effecting the optimization of tenderness in meat muscles (Ojha, 2008). None the less, the beef market success is depends upon the value consumers attribute to it. Inconsistency in the eating quality may be preventing repurchase. A study by Miler 2002, concluded that about 20 percent of beef steaks sold to consumers are tough. The central source of consumer complaint and the failure to repurchase is due to the inconsistency of eating quality especially with tenderness (Tarrant, 1998; Bindon & Jones, 2001). Inconsistency in a product can result in a decline in sales. In order to compete with other protein sources such as chicken, beef must maintain a level of quality the consumers identify as valuable. Resultantly, the meat association has developed a standardized method to measure tenderness. The Warner Bratzler Test (WBS) measures the amount of pressure required to tear through a core of meat. It is used as a quantitative tool to determine consistency of tenderness in beef. Although there are different methods to quantitatively measure tenderness, the Warner Bratzler Shear machine has been noted to be an accurate and popular method (Szczesniak and Torgeson, 1965). Research study results have suggested that the Warner-Bratzler Shear values can be used as a starting point for consumer acceptance of steak (Huffman et.al 1996). Prospectively, consistent tenderness of beef may be maintained using this method. A study evaluating the possible repeatability among institution found that the method can be repeated given a standard protocol and properly calibrated equipment. Thusly, WBS can be applied to monitor tenderness before distribution of beef steaks. The WBS values of wet aging and dry aging has been evaluated. One study examining dry versus wet aged beef palatability from choice and select short loins showed that aging treatment difference had no effect on WBS values (Smith et. al. 2008). Campbell et. al. (2001) reported steaks dry aged for 21 days had lower shear force values (P<0.05) compared to shorter aging times of 0,7,14 days. It also reported shear values of steaks dry aged for 0,7, and 14 day were similar (P>0.05). However, Laster et al., (2008) reported a significant impact of aging on WBS values showing wet aged ribeye steaks values were lower (P=0.0064) than dry aged ribeye steaks, different from that reported by Smith et al in Still, studies are limited in this regard. SENSORY ANALYSIS Consumption of chicken has increased and the demand for beef has decreased. According to Ferrier et al., (2007) beef s share of meat consumption declined from 48% to 32% as total beef consumption stagnated meanwhile other 70 Producer s Update and Research Highlights

71 meat sources like chicken and pork consumption rose. The industry was pushed to revamp products offered to fit changing consumer s needs. The industry rectified the dilemma by trying to create a unified beef source. Solutions came by setting a standard of quality attributes between producers and processors, setting acceptable levels of tenderness, and uniformity in livestock genetics to produce superior and consistent products (Purcell and Lusk, 2003). Having a standard helped improve beef. Since that time, more beef surveys were necessary to keep the industry aware of the changing needs and desires of their constituents. The number one factor that sensory administrators attempted to measure was tenderness. As stated previously, tenderness is the ultimate indicator of future purchases by consumers and also the main reason consumers choose beef outside of any nutritional reasons. Consumer surveys concluded that the lack of consistency in product s tenderness is the major concern for most consumers (McDonell, 1990; Jeremiah 1982; Jeremiah, Tong, Jones & McDonell, 1992, 1993). Many consumers attribute eating quality with distinct palatability characteristics. The six primary palatability characteristics for beef are flavor, juiciness, tenderness, aroma, texture and color. Understanding the impact of the characteristics on consumers provide a better idea of how to meet there needs and maintain a consistent level of repurchases. Sensory administrators seek to measure the characteristics that are of concern for beef which is mostly tenderness, flavor and juiciness, since other studies have confirmed consumer concerns with these qualities in particular. It can be inferred that aging, whether dry or wet, improves tenderness. But aging has also been suggested to impact flavor. As previously noted, consumers claim a difference in flavor for dry aged beef indicating a beefy brownroasted flavor. Limited studies have supported this claim while other studies have detected no difference. Laster et al., 2008 reported no significant difference for overall like, flavor and juiciness like, level of beef flavor and tenderness, or purchase intent for wet and dry aged ribeye steaks. Similarly, Parrish et al. (1991) found no significant difference in juiciness, flavor intensity, flavor desirability or overall palatability between dry and wet aged ribs and loins. Sitz et al., (2006) detected no significant differences for flavor, juiciness, or overall acceptability for strip loins. Also, Smith et al. (2008) states no significant difference for overall like, flavor like, level of beef flavor, level of tenderness, juiciness like, level of juiciness, and purchase appeal attributes from short loins. Still limited research shows no substantial support for the claims. Yet, customers request dry aged beef because of this difference they can distinguish. Consumer themselves are useful as panelists on sensory evaluations. The sensory panel is conducted to esses difference in wet or dry aged beef use trained or untrained panelists. Some concern with using untrained panelist stems from the accuracy and repeatability of the test. Studies have inferred that untrained consumer panelist can detect tenderness differences accurately. In fact, Wheeler et al., (2004) reported correlations between slice shear force and consumer panel tenderness rating increases (P<0.05) as the number of consumers in the averages increased up to eight. Furthermore the repeatability of the consumer panel tenderness rating on duplicate steaks is 0.80 suggestive of repeatable tests. Also, it reported strong correlation between the shear instrument and the untrained laboratory panel ratings (Wheeler et al., 2004). NUTRITION The connection between people and food is different now than it was several years ago. In the past, sources of food were not available all year around nor was it stored in surplus at the local market. People had to wait to harvest based on the seasons and consume meat same day. Advancements in science and engineering have drastically changed this, especially in the United States. The physical labor of hunting and gathering food was relative to the energy intake from food such is the case of Producer s Update and Research Highlights

72 any active lifestyle. Currently, the United States has strayed from this concept in that food is also consumed less for need and more so for pleasure. Unfortunately, obesity is prevalent and is reaching an epidemic level. As a result, heighten efforts to change obesity and other health concerns, in relation to nutrition, have increased recently. Some information distributed has created an interest in nutrition as it relates to beef and whether it is nutritionally beneficial or not. There are several benefits to consuming red meats. Besides eating meat muscle for desirable eating quality and pleasure, meat provides a great source of nutritional value. Meat is naturally rich in nutrients and gives a large quantity of nutrients per calories in a typical serving (Lofgren, 2005). It is also a key protein source containing about 15-35% of protein thus providing all essential amino acids and is a source of lipids among those includes omega 3-polyunsaturated fatty acids (National Health and medical Research Council, 2006). Additionally, beef supplies the B vitamins, such as Vitamin B12, and fat soluble vitamins A, D, E, K at lower levels. Beef also provides minerals like iron, selenium potassium phosphorus and zinc to name a few. Meat is noted to have a high biological value because some of the nutrients are available in forms that are readily absorbable by the body (Lofgren, 2005). Essentially, meat is an excellent source of nutritional value. In regards to beef, lipid or fats are the primary issue. Beef has a high concentration of saturated fat, thus anxiety over unhealthy amounts has increased among consumers. Studies unanimously conclude saturated fats are contributors to heart disease, cardiovascular disease, diabetes and other chronic disease (Fraser, 1999; Kelemen et al., 2005; Kontogianni et al., 2008). Modifications to beef in order to provide healthier options were conducted. The meat industry has addressed health concerns by modifying fat on beef. Majority of beef products sold are learner than they were several years ago. Increase knowledge in genetics and animal nutrition has improved fat deposition in meat muscle. Processors are also trimming excessive fat from retail cut about 1/8 inch in fat trim. There are also leaner ground beef options. Consumers can purchase a range from 5-20% fat ground beef depending on their needs or preferences. Other modifications are smaller portions of cuts since serving size is of concern too. Despite beef s excellent nutrient bioavailability, other studies have correlated beef to cancer. According to World cancer research fund/american Institute for Cancer Research (2007) red meat and processed meats are linked to colorectal cancer. For this reasons, in summation they recommended consuming no more than about 500 grams of cooked red meat per week and avoiding processed meats all together. Similar conclusions can possibly impact the beef industry causing consumers to look to alternative meat sources or purchase less or no beef. However, research is being conducted to further evaluate the correlation of dietary choices and cancer due to inconsistencies. Inevitably, this may possible increase concerns with beef wholesomeness. The aging methods must also comply with wholesomeness. Drying aging in particular may be more susceptible to oxidative rancidity which is lipid oxidation where oxygen interacts with unsaturated fatty acids which causes the production of peroxides and other secondary oxidative compound such as ketones and aldehydes (Faustman et al, 2010). These products developed from lipid oxidation are responsible for off odors and warmed over flavor (Faustman et al., 2010). Furthermore, unsaturated fatty acids, oxygen and chemicals such as metal and iron are necessary to quicken the oxidative process, Faustman et al. (2010) states these components are abundant in meat, especially those on display or high oxygen atmospheric packaging. Due to the nature of the drying process it could be suspected that the flavor development being associated with dry aged beef may be a result of lipid oxidation. Lipid oxidation does impact quality of food (Shahidi and Zhong, 2010). OXIDATIVE RANCIDITY 72 Producer s Update and Research Highlights

73 There are two kinds of lipid oxidation but the one being discussed and evaluated in this study is oxidative rancidity also known as autoxidation. Auto oxidation is the spontaneous reaction of lipids with atmospheric oxygen through a chain reaction of free radicals (Shahidi and Zhong, 2010). The results of autoxidation gives what is termed oxidative rancidity which is the changes in lipids that produce volatile compounds which gives the spoilage characteristics such as off flavoring and bitter taste, usually due to unsaturated fatty acids (Barnes and Galliard, 2007). Fatty acids, the building blocks of lipids, greatly impact the susceptibility of certain fatty acids over the other to rancidity. It has been noted that rancidity predominately affects unsaturated fatty acids in foods. The products developed from lipid oxidation are responsible for off odors and warmed over flavor (Faustman et. al., 2010). The 2-thiobarbiutic acid (TBA) is the main reagent used to determine fat auto oxidation levels in food. The compound is reactive with many carbonyl substances aldehyde and ketones which are present during autoxidation of lipids (Guillen-Sans & Guzman-Chozas, 1998). Auto oxidation levels in food are indications of rancidity which is a sensorial term referring to spoilage. The TBA assay has been widely used to detect spoilage in a wide variety of food sources including vegetable and other cooking oils. Studies of TBA assays were first described by Kohn and Liversedge (1944) on oxidation of animal tissue. They suggested the resulting reactant substance could be a carbonyl compound (Guillen-Sans & Guzman-Chozas, 1998). Bernheim et al., 1948 studied the interaction of the oxidized products and TBA. The experiments concluded the colored reaction products from the combining oxidative products and TBA reagents were alkylindenethiobarbaturic acids. Patton and Kurtz (1951) later tested the procedure in milk fat and they verified the absorption spectrum from reaction of oxidized milk fat and TBA was similar to the red pigment obtain in the reaction of malonaldeyhde (MDA) and TBA (Guillen-Sans and Guzman-Chozas, 1998). Through the experiment the authors suggested MDA was the defining component in the rancidity process and biological oxidation of unsaturated fatty acids. In the meat food sector, Turner et al. (1954) was the first author to use the procedure on frozen meat pork. These studies were the foundations for other factors specific for meat such as reproducible methods, carbohydrate presence, optimum heating time and the size of samples. Ultimately, the results of the TBA assay were suggested to be highly correlated with the oxidized flavor of animal foods such as milk (Guillen-Sans and Guzman-Chozas, 1998). MATERIALS AND METHODS Cattle came from V Bar V Ranch which is an extension of the University of Arizona Agricultural Experiment Station. All cattle were harvested at the University of Arizona Meat Science Laboratory under federal regulation and inspection. Carcasses were weighed and tagged for proper identification. Carcasses were chilled for 24 hours before being divided into treatment groups as a standard industry procedure to maximize marbling visibility and ultimately impact quality grade. Carcasses were randomly selected for treatment groups where by the rib eye steak samples were derived. Animal Harvest: All animals were slaughtered and processed in the University of Arizona Meat Science laboratory under federal inspection. All harvest procedures were approved as humane slaughter and the carcasses were weighed and tagged for proper identification. All carcasses were pre chilled for 48 hours in cooler before being divided into treatment groups. Steaks were distributed randomly into each treatment group. Wet Age Treatment Group: Steaks in the wet aged treatment group were removed from the carcass at chilling by professional butchers at the UA Producer s Update and Research Highlights

74 Meat Science Laboratory identified and vacuum packaged (4mil pouches). Steaks were then placed in the refrigerated cooler which had a temperature of about 35 ºF and age for 14 days. On days 7 and 14 a steak samples were removed for shear force, oxidative rancidity and sensory testing. The remaining steaks were re-vacuumed and returned to the cooler until the next sampling day. Dry Age Treatment Group: Carcasses were hung in the cooler for dry aging. The temperature was kept at about 35 degrees with humidity of about 80 degrees. Carcasses were hung for 14 days. Individual steaks were removed on days 7 and 14 by professional butchers at the UA Meat Science Laboratory for shear force, oxidative rancidity and sensory. Warner-Bratzler Shear Force Test: All steaks used for the Warner-Bratzler shear force test followed the procedure. Steaks were cooked on the George Forman Grill (exact model) on high. Steaks were considered done when the internal temperature reached 71 degree centigrade using a hot plate Grill (George Foreman Grilling Machine, Lake Forest, IL). A 1.3 diameter metal core was used to obtain 8 meat cores from each steak. The cores were sheared using the Warner-Bratzler shear machine. Shear values were the average of 8 meat core for each steak. 2-Thiobarbaturic Acid Test: The Tarladgis distillation method as described in (Tarladgis et al., 1960) was used to determine oxidative rancidity in meat. Procedure involves blending 10g of meat with 50 ml of distilled water in Omni Mixer (Brand make and model) for 2 min. Transfer mixture into Kjeldahl flask by washing with additional 47.5 ml of distilled water, add 2.5 HCL and Dow Antifoam A, and boiling stones to the flask. Flasks were heated on the Kjeldahl distillation apparatus on the highest possible level for approximately 10 minutes or required to collect 50ml of distillate. Then mix and pipette 5ml into 50 ml into Erlenmeyer flask, with TBA reagent added. Contents were immersed in boiling water for 35min then placed in a cool tap water after heating for 10 min. A portion was transferred into the cuvette and read optical density at 538 mu on spectrophotometer (Spectronic 20D+). Original procedures were modified to fit the specifications of the laboratory in this study. Sensory Evaluation-Survey and Panelist Sensory evaluation was conducted at the University of Arizona Meat Science Laboratory Sensory evaluation room which is structured to hold 8 panelists per evaluation. Panelists had their own cubicle which they randomly choose prior to the test. Each cubicle had a survey with instructions and a cup of water which was placed randomly in each cubicle during set up. 74 Producer s Update and Research Highlights

75 Panelists were untrained and participation was on a voluntary basis. The instructions were read aloud to make sure that it was clear and each participant understood the objective of the evaluation being given. The survey included a demographics portion which would not identify panelist but would gathered information regarding gender, age, and beef consumption customs. The sample evaluation portion used a hedonic scale of 1-8 for 4 categories which includes tenderness, juiciness, flavor intensity, and acceptance. A score of 1 denotes an unfavorable score and 8 denotes a favorable score for each trait listed above (figure 3). Panelists scored the samples by checking the appropriate box for each category. After each sample, the panelists were to sip water provided to cleanse the palate for the next sample. Sensory Evaluation-Preparation: Steaks from both treatments were thawed and cooked to 160 ºF internal temperature on the George Forman grilling machine and placed in aluminum pan to be cut into 1cm x 1cm x 1 cm squares. After cutting, steaks pieces were placed onto numbered paper plates that matched the evaluation survey for each panelist. The steak sampling order was different for each panelist to prevent any swaying of scoring. Numbers were used to identify wet aged steaks, denoted as 1, from dry aged steaks, denoted as number 2, and the order it was sampled. Panelists were not informed as to the number denotations but had to make sure the sample numbers matched the survey numbers. RESULTS AND DISCUSSION Shear Force and Oxidation Values In this study, wet versus dry aged steak shear force values were not significantly different (P>0.05) when comparing aging period 7 and 14 (Table 1). Also wet and dry aged steaks was not significantly different (P>0.05) for oxidation values when comparing aging period 7 and 14 (Table 1). Aging period significantly affect shear force (P<0.05) but showed no significant effects on oxidative values (P>0.05).This is shown in Table 1.3. Tenderness is a complex concept; many factors can influence it in the finished product. Known components affecting tenderization in meat muscle such as proteyletic enzymes, calpain and calpastatin, has yet to be understood completely although studies have been produced regarding its role in tenderness. Due to conflicting thought, this process was not evaluated. However measuring shear force is valuable information because tenderness and shear force value are correlated. Shear force value is not significantly affected by aging treatment in this study. The results are similar to that mentioned in studies by Parrish et al. (1991) and Smith et al. (2008) but contrasted with Laster et al. (2008) reports which showed aging treatment to have significant affects on shear force values of ribeye steaks and top sirloin steaks (P<0.05). However other results in this study demonstrate aging period does significantly affect shear force value thus impacting tenderness. Aging period of 14 days had a lower shear force value thus indicating 14 day aged steaks requiring less pressure to tear through the core compared to 7 day aged steaks. Results in this study are similar to reports noted by Smith et al. (2008) and Laster et al. (2008). Oxidative Rancidity was not significantly different for aging treatment or aging period. Limited studies in the area and differences in methodology between facilities make it more difficult to compare to other studies. However unpublished data by Parrish et al. (1991) also showed no significant difference in aging treatment with regard to oxidation values. Consumer Panel Under the conditions of this study tenderness was significantly different between wet and dry aging treatment in consumer sensory evaluation (P<0.05) and wet aged steaks had higher rating for tenderness than dry aged steaks. Producer s Update and Research Highlights

76 Also, all other palatability attributes did not have a significant difference between wet and dry aged steaks (P>0.05). Results are noted in Table 1.2. The results of this study are similar with studies by Parrish et al (1991) which showed a significant difference between wet and dry aged with regard to tenderness attributes. In studies by Parrish et al. (1991) and Laster et al. (2008), wet aged steaks had a higher tenderness rating which coincides with the reports of this study. Although consumers suggested a difference in palatability attributes from wet aged and dry aged beef, no significant differences were found for flavor intensity, overall acceptance and juiciness. The results of this study are similar to previous studies Parrish et al., 1991; Smith et al., 2008 and Laster et al., 2008 which all showed no differences in other palatability attributes in steaks. In contrast, Miller et al., 1985 found some significant differences in flavor for strip loin steaks. All aging treatment produced palatable products yet some grading effects were detected in previous studies that may have some impact on flavor. Smith et al (2008) and Parrish et.al (1991) reported US choice and Prime steaks were significantly different from that of US select steaks with regards to palatability attributes. In the same respect, others studies showed contrasting results Parrish et al. (1973) and Goll et al. (1965) reported no grading effects on palatability of steaks. Although this study did not measure quality this may have some impact and should be considered in future research. Cost Analysis Dry aging as noted earlier requires more time due to trimming and space. It can also be costly due to trim loss. For the sake of comparing wet aged and dry aged steaks it is beneficial to include the cost analysis. Steak Dry aged for 2 weeks(14days) has a cooler shrinkage of 4% based on 650 lbs hot carcass weight and 624lbs carcass weight after 14days aging. The loss in shrinkage is 26 lbs which equates to $52.00 or $2.00/lbs. Labor to process this type of carcass is about 4.5 hours which can produce estimate fees of about $54.00 at $12.00/hour. Using the same parameters but accounting for vacuum packaging and purge loss for wet aged carcass production can also be estimated. Vacuum packaging is estimated to require about 40 bags per carcass at $.28/bag is $ There is a 2% purge loss from vacuum packaging 390lbs of boneless primal cuts which equates to about $7.80. Given the average price of boneless cuts which comes out to $39, the total cost of producing wet aged beef is estimated to be $ The difference of producing wet aged versus dry aged beef cut is $4.20. Marketing dry aged beef may be feasible considering the premium price associated. CONCLUSIONS Tenderness is the major attribute consumers desire in beef and ultimately determine repurchase. Although dry aging was not more tender than wet aged steaks in consumer sensory panel results or showed no significant difference in other attributes, it can possibly be used as selling point for beef because of consumer interest. The beef industry may possibly market this product for a premium as consumers are willing to purchase beef they attribute more desirable characteristics. Despite the lack of scientific evidence, the rarity of dry age beef steak may generate a new market. Typically harvesting is standardized for animal humane reasons but processing facilities vary which impacts tenderness. Small processors that may not a have access to advance technology or space to produce dry aged beef can still produce palatable products. As this study shows, aging for at least 14 days can still be an effective tenderizer because there was a significant difference of aging period on shear force values although aging treatment showed no significance with regard to shear force values. In reviewing the cost effectiveness of producing wet aged beef and dry aged beef, estimates show that dry aged beef cost $4.20 more to produce but can be offset by consumer willingness to pay premium. Thus, producing either can be cost effective. 76 Producer s Update and Research Highlights

77 APPENDIX A: TABLES REFERENCES Smith, R.D., K.L. Nicholson, J.D.W. Nicholson, K.B. Harris, R.K. Miller, D.B. Griffin, J.W. Savell. (2008). Dry versus wet aging of beef: Retail cutting yields and consumer palatability evaluations of steaks from US Choice and US Select short loins. Journal of Meat Science Troy, D.J., J.P. Kerry. (2010). Consumer perception and the role of science in the meat industry. Journal of Meat Science Purcell, W.D., J. Lusk. (2003). Demand for red meats: principles research evidence and issues. The Veterinary Clinics Food Animal Practice Parrish, F.C., JR., J.A. Boles, R.E. Rust and D.G. Olson. (1991). Dry and Wet Aging Effects on Palatability Attributes of Beef Loin and Rib Producer s Update and Research Highlights

78 Steaks from Three Quality Grades. Journal of Food Science 56: Miller, R.K. (2002). Factors affecting the quality of raw meat. In J.P. Kerry, J.F. Kerry and D. Ledward (Eds.), Meat processing-improving quality (pp.27-63). Cambridge, England: Woodhead Publishing Co. Campbell, R.E., Hunt, M.C., Levis, P., and Chambers, E.IV, (2001). Dry-aging effect on palatability of beef longissimus muscle. Journal of Food Science, 66, Waren, K.E., & Kastner, C.L. (1992). A Comparison of dry-aged and vacuum-aged beef strip loins. Journal of Muscle Foods, Boeleman SJ, Boleman SL, Miller RK, Taylor JF, Cross HR, Wheeler TL, Koohmaraie M, Shackelford SD, Miller MF, West RL, Johnson DD & Savell JW (1997). Consumer evaluation of beef of known tenderness. Journal of Animal Science Tarrant PV (1998). Some recent advances and future priorities in the meat industry. Meat Science 49, Suppl. 1, S1-S16. Bindon BM & Jones NM. (2001) Cattle supply, production systems and markets for Australian beef. Austrailian Journal of Experimental Agriculture 41, Jerimaih, L.E. (1978). A Review of factors affecting meat quality. Lacombe Res. Stn.Tech Bull. No. 1, Lacombe, AB. McDonell, C (1990). Canadian consumer perception of beef. Proc. Beef conception to consumption Conference. Brandon, MD Nov Cameron Faustman, Qun Sun, Richard Mancini Surendranath P. Suman (2010). Myoglobin and lipid oxidation interactions: Mechanistic bases and control. Meat Science Jeremiah, L.E, Tong, A.K W., Jones, S.D.M, and McDonell, C. (1992). Consumer acceptance of beef with different levels of marbaling. J. Cons. Stud. Home Econ., 16, Jeremiah, L.E, Tong, A.K.W., Jones, S.D.M., McDonell, C. (1993). Canadian consumer perceptions of beef in relation to general perceptions regarding foods. J. Cons. Stud. Home Econ., 17, Peyton Ferrier, Russel Lamb (2007). Government regulation and quality in the US beef market. Food Policy P.A. Lofgren Meat, Poultry and Meat Products Encyclopedia of Human Nutrition (Second Edition) Pages online scicnedirect. com original available 2004 updated Fereidoon Shahidi and Ying Zhong (2010). Lipid oxidation and improving the oxidative stability. Chemical society review Goll D.E, Carlin A.F., Anderson L.P, Kline E.A, and Walter M.J. (1965). Effect of marbling and maturity on beef muscle characteristics II. Physical, chemical and sensory evaluation of steaks. Food Technol. 19:163. Laster M.A, Smith R.D, Nicholson K.L, Nicholson J.D.W, Harris K.B, Miller R.K, Griffin D.B, Savell J.W. (2008). Dry versus wet aging of beef: Retail cutting yields and consumer sensory attribute evaluations of steaks from ribeyes, strip loins, and top sirloins from two quality grade groups. Meat Science 80: Parrish F.C. Jr., Olson D.G, Miner B.E., Rusk R.E. (1973). Effects of degree of marbling and internal temperature of doneness on beef rib steaks. J Anim. Sci. 37:430. Patton S., Kurtz G.W, (1951). 2-thiobarbituriccid acid reagent for detecting milk fat oxidation. J. Dairy Sci., 34,669. Turner E.W, Paynter W.D, Montie E.J, Bessert M.W, Struck G.M, Olson F.C (1954) use of 2-thiobrbuturic acid reagent to measure rancidity in frozen pork. Food Technol.,8, 326. Guillen-Sans R., Guzman-Chozas M. (1998) The Thiobarbaturic Acid (TBA) Reaction in Foods: A Review. Critical Review in Food Sci and Nutrition 38(4): Bernheim F., Bernheim M.L.C., Wilbur K.M.(1948). The reaction between thiobarbituric acid and the oxidation products of certain lipids. J. Biol. Chem., 174, 257. Tarladgis B.G, Watts B.M, Younathan M.T, Dugan L. (1960). A method distillation for the quantitative determination of malonaldehyde in rancid foods. J. Am. Oil Chem. Soc. 37:44. Kohn H.I., Liversedge M., (1944). On a new aerobic metabolite whose production by brain is inhibited by apomorphine, ergotamine, epinephrine, and menadione, J. Pharmacol., 82, 292. Ojha, Jaika (2008). Comparison of feedlot performances, carcass characteristics and chemical composition of Waguli (Wagyu X Tuli) and Holstein steers. MS thesis University of Arizona. Oliver, Sandra L. Food in Colonial and Federal America [Greenwood Press:CT] 2005 Olver, Lynne. (2000). Colonial and Early American Fare. Retrieved from 78 Producer s Update and Research Highlights

79 Faculty Bios and Research Interests Ronald E. Allen Department Head, Roy and Phyllis Hislop Chair & Professor Ph.D Iowa State Research focuses on skeletal muscle growth and repair with specific emphasis on the regulation of satellite cells. Satellite cells are myogenic stem cells within muscle that have the ability to form new fibers following injury or contribute nuclei to existing fibers during growth. The specific protein growth factors and hormones that regulate the division and differentiation of satellite cells are being investigated. Mark Arns Professor & Equine Specialist Ph.D Texas A&M Research centers on both applied and basic aspects of equine reproduction, including in vitro maturation of spermatozoa, spermatozoa preservation through cold storage and cryopreservation, the influence of seminal fluids and/or its components in maturation and preservation, and reproductive management of mares and stallions. Steve W. Barham Associate Coordinator in Race Track Industry Program MBA Portland State Barham is responsible for coordinating independent study, including promoting independent study activities in the industry, tracking potential projects and assisting in matching students to these various projects. Barham has over 17 years of regulatory experience in the pari-mutuel industry having served as Executive Director of the Oregon Racing Commission from 1985 to 2002, giving him real world knowledge of regulation and the role of regulators in the racing industry Robert J. Collier Professor Ph.D University of Illinois Research focuses on effect of environment and heat stress in particular to gene function. Areas of specific research interest include nutritional, physiological, endocrine and cellular responses to heat stress. Practical management models and environmental research facilities are utilized to provide environmental conditions facing livestock in Arizona. Producer s Update and Research Highlights

80 Wendy Davis Associate Coordinator in Race Track Industry Program BS University of Arizona Davis is responsible for advising RTIP students, coordinating the internship program and teaching courses. Davis is also the RTIP s point person for the coordination and conduct of the North American Steward/ Judge Accreditation Program for flat racing, harness and greyhound stewards/judges. Vince Guerriero Jr. guerrier@u.arizona.edu Associate Professor Ph.D Syracuse University Dr. Guerriero s research focuses on cellular stress due to such factors as heat stress including the function of heat stress proteins in mammalian tissues and calmodulin regulation of smooth muscle contraction. Daniel Kiesling kiesling@ .arizona.edu Lecturer - B.S. Michigan State University Dan Kiesling serves as livestock judging coach, lecturer and student advisor. Dan is currently finishing up an MS degree in Animal Science from Iowa State University with an emphasis in beef cattle nutrition. His research project is byproduct supplementation of pasture reared finishing cattle and its effects on live animal and carcass performance and fatty acid profiles. Sean Limesand limesand@ag.arizona.edu Associate Professor Ph.D Colorado State University Research focuses on fetal development and growth, understanding how aberrant fetal nutrient and/or endocrine factors lead to postnatal complication or the fetal origins of adult disease. Seeks to identify mechanisms that alter pancreatic structure, physiology and metabolism in intrauterine growth restricted offspring to provide treatment strategies. Nathan Long nlong1@ .arizona.edu Assistant Professor - Ph.D. Oklahoma State University Dr. Long began his position with the University of Arizona in May 2011 and will be researching the effects of maternal nutrition during gestation on fetal growth and development and how these changes in fetal development affect the postnatal offspring. He will also have the opportunity to perform research on feedlot nutrition and growth and development, postpartum reproductive physiology and general cattle management research. 80 Producer s Update and Research Highlights

81 John A. Marchello Professor Ph.D Colorado State University Dr. Marchello has been a member of the University of Arizona Animal Sciences faculty since He serves as a Professor of Meat Science and Muscle Biology and his courses focus on food safety issues, meat animal evaluation, carcasses and meat cuts. He also manages the U of A Meat Science Center, which is a USDA inspected meat processing facility. His research interests include Meat Science and Muscle Biology, as well as safety issues regarding meat animals and other food items. Benjamin Renquist benjamin.renquist@vanderbilt.edu Assistant Professor - Ph.D University of California, Davis Dr. Renquist will begin his position with the University of Arizona in August 2011 initially focusing on research examining the control of food intake. He will also continue to examine the relationship between nutritional status and reproductive performance that he began while completing his Ph.D. F. Douglas Reed dreed@ag.arizona.edu Director & Professor in Race Track Industry Program MBA University of Arizona Reed has extensive experience as a racing official, track manager and racing and gaming industry consultant. He has been affiliated with the RTIP for 12 years and is responsible for all aspects of the racing program, including administration, instruction, promotion and fundraising. He is also director of the RTIP s annual Symposium on Racing & Gaming, the world s largest pari-mutuel racing conference. Dave Schafer dschafer@ag.arizona.edu Resident Director of V-Bar-V Ranch - Ph.D Colorado State University Research at the V-Bar-V addresses environmental, wildlife and domestic livestock issues applicable to Arizona and the Southwest. The historic V Bar V is a 57-pasture grazing allotment totaling 77,000 acres that runs about 30 miles east from Camp Verde along the Mogollon Rim. Research involves an applied approach to problem-solving, rather than laboratory studies in basic science. Current studies focus on three main areas: cow herd management; range and watershed activities, and wildlife interactions, particularly with elk. John Smith Senior Dairy Extension Specialist - Ph.D University of Missouri Dr. John Smith comes to the University of Arizona from Kansas State University where he served as Extension Specialist, Dairy Science in the Department of Animal Sciences and Industry. His interests include cow comfort, heat stress, milking parlor performance, special needs facilities and management of expanding dairies. Dr. Smith works throughout the United States and internationally assisting producers with the development of efficient dairy operations. Producer s Update and Research Highlights

82 William A. Schurg Professor and Equine Specialist Ph.D Oregon State University Dr. Schurg is responsible for the introductory and nutrition courses in the equine sciences program within the Animal Sciences Department at the U of A. Dr. Schurg also contributes to the Animal Industry, Principles of Nutrition and Applied Animal Nutrition courses each year with guest lectures. Dr. Schurg s research focuses on the nutritional and exertional factors affecting athletic ability of equine animals. Laura Walker llwalker@cals.arizona.edu Instructional Specialist Coordinator and Equine Center Manager - M.Ag. Texas A&M Laura Walker has been involved in the horse industry for over 20 years through her education, work experience and instructional experience. Walker manages the Equine Center overseeing daily operations, breeding, horse care, and training. Jim Sprinkle sprinkle@ag.arizona.edu Area Extension Agent in Animal Sciences Ph.D Texas A&M Jim Sprinkle is headquartered in Payson and covers primarily Yavapai and Gila counties but also works statewide in cooperation with other extension agents. Most of his work deals with range monitoring, range issues with agencies, range beef cow production and range nutrition. His current research is in the area of beef cattle trace mineral nutrition. 82 Producer s Update and Research Highlights