The Pennsylvania State University. The Graduate School. College of Agricultural Sciences

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1 The Pennsylvania State University The Graduate School College of Agricultural Sciences EFFECT OF CORN PARTICLE SIZE MILLING ON BROILER, PULLET, AND LAYER GROWTH, PERFORMANCE, AND DIGESTIBILITY A Thesis in Animal Science by Lisa Dorene Kitto 2017 Lisa Dorene Kitto Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science December 2017

2 The thesis of Lisa Dorene Kitto was reviewed and approved* by the following: Paul H. Patterson Professor of Poultry Science Thesis Co-Advisor R. Michael Hulet Emeritus Associate Professor of Poultry Science Thesis Co-Advisor Alan L. Johnson Walther H. Ott Professor in Avian Biology Gregory W. Roth Professor of Agronomy Terry D. Etherton Distinguished Professor of Animal Nutrition Head of the Department of Animal Science *Signatures are on file in the Graduate School ii

3 ABSTRACT Corn particle size (PS) is a relatively unexplored topic regarding its impact on commercial poultry performance grown for meat or eggs. Additionally, there are potential feed fabrication aspects to consider as mills could potentially save machine energy, wear, and money by modifying PS. The objectives of the following studies were to: 1) assess hammer mill energy usage and economic efficiency grinding corn to different geometric mean diameters (GMD), 2) evaluate the nutrient digestibility, growth performance, and carcass characteristics of broiler chickens fed treatment GMD corn, and 3) evaluate the growth and performance of pullets and subsequent productivity and egg quality of laying hens fed corn GMD treatments. Cooperator feed mill Wenger Feeds, LLC (Rheems, PA) delivered two batches of corn ground to 600, 900, 1200, and 1500 µm by hammer mill. Energy and machine efficiency show larger PS (1200 and 1500 µm) lend themselves to greater efficiency, tonnes per hour (TPH) throughput, and lower cost/tonne than 600 and 900 µm. Four live bird studies followed: First, a broiler digestibility study was conducted where apparent ileal digestibility (AID) and true ileal digestibility (TID), which are ways to measure the ability of amino acids to be absorbed into the bloodstream through the gastrointestinal tract, and were measured to determine level of nutrient absorption through the small intestine of 35 day old male broilers. Second, a broiler floor pen study at commercial bird density was performed with crumbled and pelleted diets. Birds fed the 600 and 900 µm corn diets showed increased body weight (BW) and body weight gain (BWG) but no significant differences between treatments for feed intake (FI) or feed conversion ratio (FC). In a third study, commercial egg laying pullet chicks fed the 600 µm corn through to maturity had consistently heavier BW than those of other PS treatments. Lastly, from weeks of age, hens in conventional cages were fed corn based treatment diets formulated in a phase fed program, with diets consisting of 50-60% ground treatment corn. Throughout the hen study there were no iii

4 significant differences with the exception of yolk color, which was measured using a Roche yolk color fan and is tied to consumer preference. It was found the 600 µm treatment yolks were reduced compared to the 900, 1200, and 1500 µm treatments at 35, 43 weeks of age, and overall. Body weight (BW), FI, day at first egg, and the number of preovulatory follicles, those follicles in the rapid growth phase before selection, remained unchanged throughout the hen study, indicating corn particle size has little to no effect on hen BW, nutrient utilization for follicular recruitment, egg production, or quality of commercial hens. iv

5 TABLE OF CONTENTS LIST OF FIGURES... viii LIST OF TABLES... ix ABBREVIATIONS... xii ACKNOWLEDGEMENTS... xiii Chapter 1 INTRODUCTION... 1 RATIONALE... 1 HYPOTHESIS... 2 OBJECTIVES... 2 REFERENCES... 4 Chapter 2 LITERATURE REVIEW... 5 Corn Carbohydrate Metabolism... 5 Mill Performance... 6 Hammer Mill vs. Roller Mill Performance... 6 Machinery Energy Usage... 8 The Pelleting Process... 8 Bird Live Performance... 9 Broilers Pullets and Layers Other Species and Nutrients Live Production and Mill Mechanic Synchronicity REFERENCES Chapter 3 CORN PARTICLE SIZE SEPARATION AND HAMMER MILL PERFORMANCE ABSTRACT INTRODUCTION MATERIALS AND METHODS Corn Milling and Economics Sieving and Calculations Statistical Analysis Nutrient Analysis RESULTS AND DISCUSSION ACKNOWLEDGEMENTS REFERENCES Chapter 4 EFFECT OF CORN PARTICLE SIZE ON APPARENT AND TRUE ILEAL DIGESTABILITY AND JEJUNUM VISCOSITY OF 35-DAY OLD MALE BROILERS v

6 ABSTRACT INTRODUCTION MATERIALS AND METHODS Birds and Housing Treatment Diet Formulation for the Digestibility Assay Digestibility Assay Viscosity Assay Nutrient Analysis of Digesta and Complete Treatment Diets Calculations Statistical Analysis RESULTS AND DISCUSSION ACKNOWLEDEMENTS REFERENCES Chapter 5 CORN PARTICLE SIZE EFFECTS IN PELLETED AND CRUMBLED DIETS ON BROILER GROWTH PERFORMANCE AND CARCASS CHARACTERISTICS ABSTRACT INTRODUCTION MATERIALS AND METHODS Birds and Housing Statistical Analysis RESULTS AND DISCUSSION ACKNOWLEDGEMENTS REFERENCES Chapter 6 EFFECTS OF CORN PARTICLE SIZE ON PULLET GROWTH PERFORMANCE AND REPRODUCTIVE TRACT DEVELOPMENT ABSTRACT INTRODUCTION MATERIALS AND METHODS Birds and Housing Body Weight, Growth Performance, and Organ Measurements Statistical Analysis RESULTS AND DISCUSSION ACKNOWLEDGEMENTS REFERENCES Chapter 7 EFFECT OF CORN PARTICLE SIZE ON HEN PERFORMANCE, EGG QUALITY AND ECONOMICS ABSTRACT INTRODUCTION MATERIALS AND METHODS Birds and Housing Treatment Diet Formulation Data Collection vi

7 Body Weight and Production Data Egg Production & Quality Parameters Gastrointestinal Tract Measurements and Preovulatory Follicle Determination Statistical Analysis RESULTS AND DISCUSSION ACKNOWLEDGEMENTS REFERENCES Chapter 8 CONCLUSIONS AND FUTURE WORK APPENDIX A Chapter 6 Summary Tables APPENDIX B Chapter 7 Summary Tables vii

8 LIST OF FIGURES Figure 3-1. Corn particle sieving percent separation: 600µm Delivery 1 vs. Delivery Figure 3-2. Corn particle sieving percent separation: 900µm Delivery 1 vs. Delivery Figure 3-3. Corn particle sieving percent separation: 1200µm Delivery 1 vs. Delivery Figure 3-4. Corn particle sieving percent separation: 1500µm Delivery 1 vs. Delivery Figure 4-1. Apparent ileal AA digestibility (%, DM basis) Figure 4-2. True ileal AA digestibility (%, DM basis) Figure 4-3. True ileal AA digestibility with literature EAAL values (%, DM basis) viii

9 LIST OF TABLES Table 3-1. Hammermill economic cost (average amperage, power, TPH, efficiency, cost/tonne & hr/tonne) Table 3-2. Corn particle size distribution: Percent separation (%) Delivery 1 1, Table 3-3. Corn particle size distribution: Percent separation (%) Delivery 2 1, Table 3-4. Corn treatment particle size sieving: GMD and GSD 1, Table 3-5. Nutrient composition of corn ( as is basis) Table 4-1. Nutrient composition of experimental diets for digestibility ( as is basis) Table 4-2. Mean body weight (BW, kg/bird) and body weight gain (BWG, kg/bd) 1, Table 4-3. Mean ileal endogenous amino acid losses (g/100 g DM) collected from the terminal end of the ileum 1, Table 4-4. Apparent ileal AA digestibility (%) Table 4-5. True ileal AA digestibility (%) Table 4-6. True AA ileal digestibility (%) from literature EAAL values Table 4-7. Jejunum digesta viscosity of male broilers at 35 days (cp) 1, Table 5-1. Proximate analysis of completed broiler feed (%) Table 5-2. Floor-pen broiler body weight (BW, kg/bd) Table 5-3. Floor-pen broiler body weight gain (BWG, kg/bd) Table 5-4. Floor-pen broiler feed intake (FI, kg feed/bd) Table 5-5. Floor-pen broiler feed conversion (FC, kg feed/kg BWG) Table 5-6. Floor-pen broiler percent mortality and culls (%) Table 5-7. Floor-pen broiler female mean processing weights (g) Table 5-8. Floor-pen broiler female mean processing weights as a percent of carcass weight at 42d 1,2 (%) Table 5-9. Floor-pen broiler male mean processing weights (g) ix

10 Table Floor-pen broiler male mean processing weights as a percent of carcass weight at 42d (%) 1, Table Floor-pen broiler combined male and female mean processing weights (g) Table Floor-pen broiler combined male and female mean processing weights as a percent of carcass weight at 42d (%) 1, Table Floor-pen broiler female organ weights (g) and lengths (cm) 1, Table Floor-pen broiler male organ weights (g) and lengths (cm) 1, Table Floor-pen broiler combined organ weights (g) and lengths (cm) 1, Table 6-1. Pullet body weight (BW, g/bird) and body weight gain (BWG, g/bird) 1, Table 6-2. Pullet feed intake (FI, g/bird/day) 1, Table 6-3. Pullet feed conversion (FC, g feed/g gain) 1, Table 6-4. Pullet organ weights and lengths (16 weeks) Table 7-1. Mean hen day egg production (%) by dietary treatment Table 7-2. Mean eggs per period (28d) per hen housed by dietary treatment Table 7-3. Hen body weight (BW, kg) Table 7-4. Egg weights (g) Table 7-5. Feed intake (g/hen/day) Table 7-6. Feed conversion (kg feed/dozen eggs) Table 7-7. Feed conversion (kg feed/kg eggs) Table 7-8. Egg quality Table 7-9. Pullet organ weights and lengths (19 weeks) Table Hen organ weights and lengths (31 weeks) Table Hen organ weights as a percent of BW (%) (31 weeks) 1, Appendix A.1. Pullet starter diets Appendix A.2. Pullet grower diets Appendix A.3. Pullet developer diets x

11 Appendix A.4. Pullet pre-lay diets Appendix B.1. Hen diets phase 1, periods 1 & Appendix B.2. Hen diets phase 1, periods 3 & Appendix B.3. Hen diets phase 2, periods 5 & Appendix B.4. Egg proportions (g) Appendix B.5. Hen organ weights and lengths (43 weeks) Appendix B.6. Hen organ weight as a percent of body weight (%) (43 weeks) 1, xi

12 ABBREVIATIONS µm = Microns AA = Amino acid AA diet = Amino acid concentration in diet AA digesta = Amino acid concentration in ileal digesta AIA diet = Acid insoluble ash concentration in diet AIA digesta = Acid insoluble ash concentration in ileal digesta AID = Apparent ileal amino acid digestibility BW = Body weight BWG = Body weight gain CF = Crude fiber CP = Crude protein cp = Centipoises Delivery 1 = Ground corn delivered February 2016 Delivery 2 = Ground corn delivered October 2016 DM = Dry matter EAAL = Endogenous amino acid loss concentration (current study) EAAL Lit = Endogenous amino acid loss concentration (Lemme et al. 2004) EE = Ether extract EHC = Enzymatically hydrolyzed casein ESCL = University of Missouri Agricultural Experiment Station Chemical Lab FC = Feed conversion ratio FI = Feed intake g = Grams GMD = Geometric mean diameter (µm) GSD = Geometric standard deviation (µm) IACUC = Institutional animal care and use committee kg = Kilograms KW = Kilowatts KWh = Kilowatt hours ME = Metabolizable energy PDI = Pellet durability index PF = Protein-free diet PS = Particle size RPM = Revolutions per minute SEM = Pooled standard error of the means TID = True ileal amino acid digestibility TID Lit = True ileal amino acid digestibility using EAAL Lit TPH = Throughput (tonnes/hour) V = Volts VFD = Variable frequency drive xii

13 ACKNOWLEDGEMENTS These studies were funded through the 2015 Pennsylvania Poultry Industry Egg and Broiler Research Check-Off Programs. Special thanks to my advisors Dr. Paul Patterson and Dr. Michael Hulet for their guidance, understanding, and support through my time at Penn State. I am so thankful for everything they have taught me over my time here and wouldn t trade those lessons for the world. Thanks also to my committee members Dr. Alan Johnson and Dr. Greg Roth for imparting their knowledge and valuable advice on me through my studies. I also wish to thank Dr. Jude Liu, Dr. Virendra Puri, Dr. Hojaye Yi, Jill Hadley, and Kate Anthony for all their help and assistance in completing my projects. I d like to sincerely thank everyone at The Penn State Poultry Education Research Center (Scott Kephart, Tim Price, Dave Witherite, and Ben Kunkel) for their hard work and willingness to help with these projects. Thank you to Wenger Feeds, LLC, specifically Chris Olinger, Doug Goodling, and Larry Hammaker for cooperating with us on these projects, including manufacturing all of the treatment corn particle sizes, delivery of corn, and broiler feed for all projects. Your aid has been invaluable. Finally, thank you to my friends, especially Amy Barkley and Erica Rogers for their research support and friendship I never could have completed everything without their help. Thank you to my parents, Leslie and George, for always pushing me to reach my goals, and reminding me to never let anything get in the way of those goals. Evrard, my love, thank you so much for the constant support, love, and steady supply of dark chocolate through my studies, I can never thank you enough for everything you have done and continue to do for me every single day. xiii

14 Chapter 1 INTRODUCTION RATIONALE In the poultry industry, feed ingredient costs have risen considerably in the past 10 years, accounting for nearly 70% of all live production costs (Donohue and Cunningham, 2009). With the average US poultry diet containing 60% corn (Leeson and Summers, 2005), final determination of an optimum corn particle size (PS) for the poultry industry (broilers, pullets, and layers, specifically) is of greater importance now more than ever. Despite work having been done in this particular field, results are contradictory and the live production studies may have confounding factors. For example, previous work has shown no differences in percent separation between PS treatments after the pelleting process (Engberg et al., 2002; Amerah et al., 2008), while other studies have noted differences in particle separation have remained pre- and post-pelleting (Péron et al., 2005) when utilizing ground wheat in pelleted broiler diets. Along with feed form, other parameters influence optimum PS, such as pelleting method, grain type, and grinding method (Amerah et al., 2007). While more finely ground ingredients have been thought to produce pellets with a higher pellet durability index (PDI), corn flowability through bins and chutes of a feed mill may be impaired such that the mechanical energy cost and loss of flowability are too great for a feed mill to sustain. Bird live performance also must be evaluated, as previous work has shown birds preference for larger particle size increases as they age and their mouth gape increases (Nir et al., 1994b). Additionally, it has been determined that birds prefer more uniform feed particles when in a mash form, and the more uniform a feed is, the less time a bird will spend looking for and 1

15 ultimately choosing larger particles (Nir et al., 1994a). Ultimately, weighing the benefits and costs of the wide range of commonly used corn particle sizes utilized in the commercial poultry industry may lead to a greater understanding of which corn PS is most appropriate for a given type of bird at a specific age and perhaps realize cost savings benefits for both bird live performance and for feed mills. HYPOTHESIS Particle size will affect broiler and pullet nutrient digestibility and growth performance, as well as hen performance, measured by egg production, and optimization of corn particle size can contribute to cost-savings for feed mills for all commercial poultry. OBJECTIVES 1. To assess milling energy usage, economic efficiency and particle size distribution of corn ground for different geometric mean diameters. 2. To evaluate broiler chicken nutrient absorption and live performance. a. To measure the apparent and true digestibility of four treatment corn particle sizes (600, 900, 1200, and 1500 µm). b. To measure the jejunum digesta viscosity of the four treatment corn particle sizes. c. To assess the impact of corn particle size on broiler live performance (growth, feed intake, feed conversion, carcass characteristics) and gastrointestinal organ measurements. 2

16 3. To evaluate the impact of corn particle size on the growth of pullets and their subsequent productivity and egg quality as laying hens. a. To establish if there is an impact of corn particle size (600, 900, 1200, and 1500 µm) on pullet growth and reproductive performance, including body weight, body weight gain, feed intake and feed conversion. b. To assess the impact of corn particle size (600, 900, 1200, and 1500 µm) on laying hen performance, including percent production, feed conversion (kg feed/ kg egg and kg feed/ dozen eggs), body weight, and mean eggs per hen in a 28 d period. c. Finally, to establish which corn particle size has the most positive economic impact on egg quality and egg proportions in terms of albumen height, accompanying Haugh units, yolk color, and egg proportions. 3

17 REFERENCES Amerah, A. M., V. Ravindran, R. G. Lentle, and D. G. Thomas Feed particle size: Implications on the digestion and performance of poultry. Worlds. Poult. Sci. J. 63: Amerah, A. M., V. Ravindran, R. G. Lentle, and D. G. Thomas Influence of feed particle size on the performance, energy utilization, digestive tract development, and digesta parameters of broiler starters fed wheat- and corn-based diets. Poult. Sci. 87: Donohue, M., and D. L. Cunningham Effects of grain and oilseed prices on the costs of US poultry production. J. Appl. Poult. Res. 18: Engberg, R. M., M. S. Hedemann, and B. B. Jensen The influence of grinding and pelleting of feed on the microbial composition and activity in the digestive tract of broiler chickens. Br. Poult. Sci. 43: Leeson, S., and J. D. Summers Commercial Poultry Nutrition. 3rd Ed. Context Products Ltd., Packington, Leicestershire England. Nir, I., R. Hillel, G. Shefet, and Z. Nitsan. 1994a. Effect of grain particle size on performance: 2. Grain texture interactions. Poult. Sci. 73: Nir, I., G. Shefet, and Y. Aaroni. 1994b. Effect of particle size on performance: 1. Corn. Poult. Sci. 73: Péron, A., D. Bastianelli, F. X. Oury, J. Gomez, and B. Carré Effects of food deprivation and particle size of ground wheat on digestibility of food components in broilers fed on a pelleted diet. Br. Poult. Sci. 46:

18 Chapter 2 LITERATURE REVIEW Corn Carbohydrate Metabolism Corn has become the worldwide standard cereal grain in poultry feed to which all high energy yielding ingredients are compared. Historically, nearly 75% of all corn produced in the United States has been used for animal feed (Tollenaar and Dwyer, 1999), and feed ingredients are still considered to be the most costly component of poultry production, at nearly 69% of all live production cost in 2008 (Donohue and Cunningham, 2009). Furthermore, corn accounts for approximately 60% of a standard commercial US poultry diet (Leeson and Summers, 1984). Corn is widely used because of the high starch content in the endosperm, which accounts for 83% of total kernel (Tollenaar and Dwyer, 1999). Between 2002 and 2008, corn utilized for ethanol production in the United States increased from 11% to 30% of the total available corn crop in the country (Donohue and Cunningham, 2009). Starch is part of the large class of macronutrients called carbohydrates, which also include sugars and cellulose. The simplest of carbohydrates that a bird can readily use in metabolic processes are called monosaccharides, such as glucose. Starch is easily broken down in the gastrointestinal tract, beginning in the mouth and crop with the salivary enzyme amylase. Once in the chicken s proventriculus, hydrochloric acid, pepsin, and other digestive enzymes are secreted, beginning chemical carbohydrate breakdown. Manual breakdown of feed particles occurs once it moves into the gizzard, where strong muscles mash feed and digestive enzymes from the proventriculus, facilitate mechanical and chemical breakdown. The small intestine can be segregated into three sections: the duodenal loop with pancreas and gall bladder, the jejunum at the distal end of the duodenal loop to Meckel s diverticulum, and the ileum from Meckel s diverticulum to the ileo-cecal junction is the last section of the small intestine. By the time feed 5

19 enters the small intestine, any large chain starch molecules are broken down to single glucose molecules, which poultry can easily absorb. Approximately 80% of glucose absorption occurs through active transport in the small intestine, though small amounts of carbohydrate absorption occur in the cecum (Denbow, 2000). Mill Performance While corn has been the standard energy-yielding feed ingredient in the United States for poultry, little attention has been paid to the milling aspects of corn particle size (PS). As corn is generally brought to feed mills whole, corn endosperm hardness and percent moisture are corn factors which can affect PS reduction, and while no hard and fast rules exist for types of machinery to reduce PS, two common types of equipment; the hammer mill and the roller mill may be used. Historically, individual mill settings varied for coarse, medium, and fine grinds. Currently, most mills now utilize a standard set of screens and a sieve shaker, such as that described in ASABE Standard S319.4 (2008). This standardization allows PS determination across feed mills in terms final geometric mean diameter (GMD) and geometric standard deviation (GSD) rather than coarse, medium, or fine terminology. Hammer Mill vs. Roller Mill Performance The primary goal of PS reduction for corn is to physically break it down, exposing the interior endosperm layers and increasing the surface area which aids digestive enzyme action. The hammer mill, which is utilized more frequently in industry settings, utilizes fast moving hammers to break the corn to fit though a chosen screen size (Koch, 2002). These screens can be changed out as needed by the feed mill based on their PS goal. Particles created using a hammer 6

20 mill tend to be spherical in shape but tend to have a higher geometric standard deviation (GSD). Roller mills press corn between multiple sets of horizontal rollers with constant pressure on each set of rollers. Unlike hammer mills, roller mills tend to produce particles which result in a small GSD, are more energy efficient, but have increased maintenance costs compared to hammer mills (Koch, 2002). Roller mills have been found to have greater energy savings for coarse ground particles (over 1,000 µm) compared to the hammer mill, but as PS decreases, the savings become minimal (Behnke, 1996). Previous work has been done comparing hammer mill and roller mill ground corn for bird live performance. Reece et al., (1985) concluded that corn ground using a roller mill to a GMD of 1,343 µm or using a hammer mill to 814 µm and then made into crumbled feed, found broilers fed the roller mill corn to have performed equally to those birds fed the hammer mill ground corn when grown to 47 days of age. Cereal grain type can also impact final PS, GMD, and GSD. Milanovic (2017) reported cereal grains which are more fibrous (barley or oats) are less efficiently ground than more brittle cereal grains, such as corn or wheat. Corn and wheat ground using a hammer mill with either a 1- or 7-mm screen (fine or coarse ground, respectively) found corn had a GMD of 297 µm or 528 µm, respectively, and wheat was 284 µm or 890 µm GMD, respectively (Amerah et al., 2007, 2008), indicating cereal grain types will behave differently due to inherent properties of each grain type. Cereal grains with high moisture content have been found to increase energy consumption of both hammer and roller mills (Milanovic, 2017) and ingredient is the second most expensive operation in the feed manufacturing process after pelleting according to Reece et al. (1985). 7

21 Machinery Energy Usage The cost of feed production, including equipment, energy, maintenance, as well as labor, land, building and feed ingredient procurement are related to the economic return for all types of poultry production (CPM, 2017). While the hammer mill is more commonly used in commercial practice, it can also be more expensive to run due to greater its electrical usage compared to roller mill usage. Type of mill used to grind corn can also affect overall energy costs. For example, a roller mill and hammer mill both set to grind 29,000 tonnes of corn yearly to a GMD of 600 µm would cost a feed mill operating a hammer mill $14,000 and a roller mill $8,000 in electrical costs, resulting in a cost savings of $6,000 yearly (CPM, 2017). The electrical costs of a hammer mill grinding 29,000 tonnes of corn per year to either 1200 µm or 600 µm, is approximately $3,000 and $14,000, respectively (CPM, 2017). Interestingly, screen size of hammer mills also affects energy usage and grain reduction as large screen openings result in less particles colliding with the hammers and screen, reducing energy consumption as a result of PS reduction (Martin, 1985). Finer grinding of cereal grains decreases throughput (TPH, tonnes/hr) and slows down feed mill production rates. Greater PS increases mill efficiency with greater grain flowability, TPH and reduced energy costs that can decrease final feed costs incurred by poultry producers. The Pelleting Process Finer corn particles produce more durable, high quality pellets with less fines. The poultry industry pellets and crumbles broiler feed rather than feed a mash diet because it significantly increases feed intake (FI), body weight (BW), and body weight gain (BWG) (Engberg et al., 2002). Desire for a high quality pellet or crumble currently leads the US poultry industry to grind corn more finely, as it is believed pelleting also removes the bird s ability to 8

22 waste time and energy searching and ultimately selecting larger particles as the feed is more uniform in pelleted and crumbled feed compared to a mash diet (Portella et al., 1988). Reece et al. (1986a) ground corn to a GMD of 679, 987, or 1,289 µm and subsequently pelleted the diets. The resulting pellets from the 1,289 µm corn treatment had a significantly higher pellet durability index (PDI) than the two more finely ground treatments. Another study by Reece et al. (1985) utilized hammer mill ground corn (814 µm GMD) created using a screen size of 0.48 cm in diameter, or roller mill ground corn created using one set of rollers with 2 grooves/cm, mm spacing between roller pairs, while the bottom rollers had 5.1 grooves/cm with mm spacing and generated corn at 1,343 µm GMD. The roller mill reduced energy required to grind the corn by 14.5% compared to a hammer mill. Engberg et al. (2002) and Péron et al. (2005) determined the pelleting process breaks larger particles between the pellet rollers and the die, effectively removing differences between PS treatments of wheat (Engberg et al., 2002). Other research has found that PS can be maintained through the pelleting process (Nir et al., 1995). Their study examining four treatments of varying PDI, PS and feed form evaluated both high- and lowquality pellets (88% and 66% PDI, respectively), ground corn (2600 µm GMD) added postpelleting (89% PDI), and ground corn (1200 µm GMD) fed as a mash. They determined broilers fed the mash PS treatment had significantly poorer BWG and meat recovered than all other treatments and broilers fed high-quality pellets showed higher overall BW and FI than those birds fed low-quality pellets. Bird Live Performance Beak size and gape have been found to influence a bird s preference for feed PS. Young chickens are unable to consume larger particles easily, though have been found to prefer larger particles as they age and their beak increases in size (Morgan and Heywang, 1941; Nir et al., 9

23 1994b). Birds search for, and ultimately choose larger particles, and the more uniform a diet is, the less time a bird will spend searching for its meal (Nir et al., 1994a). Broilers Efficiency is the primary goal in commercial broiler production, as the greatest production levels are realized in birds with the greatest body weight (BW) and body weight gain (BWG) with the lowest feed conversion (FC). Pelleting and crumbling feed is a great part of better FC as birds are physically able to consume more feed in a more efficient way while still absorbing and utilizing nutrients as efficiently as a mash diet. By pelleting, particle selection among broilers is reduced. Previous studies have focused on cereal grain PS in mash diets to measure differences. Nir et al. (1994b) found corn ground to coarse (2010 µm), medium (897 µm), and fine (525 µm) GMD in diets fed to broilers through 21 days of age had improved BW and BWG when fed the coarse or medium corn over the finely ground corn in mash form. This indicates that feed uniformity is of great importance when mash diets are being fed. Nir et al. (1995) reported PS can be maintained through the pelleting process when utilizing sorghum and wheat based diets. Reece et al. (1986b) examined broilers fed a crumbled starter and pelleted grower diets incorporating a fine or medium PS of wheat (300 or 955 µm GMD, respectively) and subsequently found the treatments had equal growth performance with no negative effects as a result of greater PS. Additional work has evaluated the impact of diet ingredient PS on broiler gastrointestinal tract lengths and weights. Larger, more coarse particles maintain a slower passage rate through the digestive tract than finer particles, which allows for greater exposure time for digestive enzymes to work upon the particles, possibly improving nutrient utilization and digestibility (Carré, 2000). The small intestine is of greatest interest, as the grand majority of nutrient 10

24 absorption occurs in this part of the gastrointestinal tract. Taylor and Jones (2004) fed broilers wheat based diets and reported no differences in duodenum weight but significantly greater duodenum length in birds fed whole wheat compared to birds fed ground and pelleted wheat diets. Multiple studies (Nir et al., 1995; Engberg et al., 2002) found gizzard weight and small intestine segment lengths were significantly reduced when birds were fed pelleted or crumbled diets rather than mash utilizing the same original PS in all treatments. This effect could be due to varying PS as well as the process of pressing and heating pellets as they re formed and further breaking down carbohydrate bonds. Pullets and Layers Historical work focusing specifically on ingredient PS in pullets and layer diets is minimal, though some research suggests that more focus on cereal grain PS in the growth period of younger pullets could have great impact on BW and BWG between hatch and 16 weeks of age. Frikha et al. (2011) studied brown egg laying hen pullets fed either corn or wheat (at 50% of their diet) ground through a 6-, 8-, or 10-mm screen, and found the finely ground corn (929 µm geometric mean diameter) had significantly better BWG and FC through 6 weeks of age than greater corn particle sizes measured at 991 µm and 1,042 µm GMD, and all wheat treatments (967, 1119, 1216 µm). While the studies herein focus solely on Hy-Line W-36 pullets and laying hens, work by Leeson et al. (1997) considered strains of laying hens in terms of how they choose and digest protein, as crude protein (CP) availability is also thought to be impacted by grain PS. Leeson et al. (1997) fed Babcock, DeKalb, H & N, and Shaver pullets either a conventional diet with 19.5% CP or low CP (16.5%) diet with similar Lys and Met + Cys concentrations and saw no significant differences between rearing diet treatment by 18 weeks and concluded minor strain differences exist in the pullet stage of life when considering level of protein in a diet. However, 11

25 cereal PS in concert with varying CP levels in a pullet diet could alter performance and reproductive growth in the pullet stage of life. Additionally, pullets which were lighter in BW at 18 weeks of age consumed less feed, reached sexual maturity later, and laid lighter weighted eggs and less overall egg mass, by 70 weeks of age than a heavier pullet (Leeson et al., 1997). While potential differences between PS treatments may exist in pullets, previous work available on laying hens indicates there is little difference in production performance parameters. Deaton et al. (1988) fed corn ground by roller (1,343 1,501 µm) or hammer mill ( µm) into laying hen mash diets and found PS range did not influence hen percent egg production, BW, egg weight, FI, FC (g feed/g egg), or eggshell breaking strength. Morgan and Heywang, (1941) determined pelleting hen diets can reduce feed wastage, hen energy expenditure and time spent choosing or eating feed, thus improving nutrient uptake. Hy-Line (2016) recommends pullets be fed a crumbled starter and later a mash grower diet with 25% of particles less than 1,000 µm, 65% between 1,000 2,000 µm and 10% between 2,000 3,000 µm. For pullet developer and laying hen diets they recommend increasing the range to include 35% PS between 1,000 2,000 µm and 2,000 3,000 µm plus 5% of particles greater than 3,000 µm. These recommendations suggest a smaller PS is more beneficial for younger, smaller pullets. More recently, Safaa et al. (2009) ground dent corn or Durum wheat to pass through either a 6-, 8-, or 10-mm screens on a hammer mill, where the ground corn GMDs ranged from 774, 922, and 1165 µm and ground wheat GMDs ranged from 998, 1,111, 1,250 µm. These corn and wheat PS were fed to Lohmann Brown hens from 20 to 48 weeks of age, and it was determined there were no significant differences between grain type, or coarseness of grind, and all production and egg quality parameters remained unaffected. However, FI increased slightly with greater PS notwithstanding cereal grain type (107.9, vs g/bd/d). Similarly, Hamilton and Proudfoot (1995) fed White Leghorn hens wheat ground to either a fine or coarse PS in a mash diet (GMD was never defined), and reported hen BW, egg production, weight, and 12

26 FC were not significantly impacted by PS treatments throughout the study. These studies suggest hen performance and egg parameters are not influenced by ingredient PS in mash diets. Other Species and Nutrients Focusing on calcium source and PS for laying Longyan ducks (Wang et al., 2014) evaluated limestone and oyster shell at two particle sizes (either < 100 µm or between 850 2,000 µm GMD) from weeks of age, and reported limestone with greater PS was more efficiently utilized by the ducks and had significantly greater egg production, egg quality, and bone strength as a result, indicating an effect from the differing particle sizes of the limestone and oyster shell. Much like the poultry industry, the swine industry has been interested in cereal grain PS, its impact on feed costs, live performance, and carcass characteristics. Refining the impact of ingredient PS is hampered by application of terms like fine, medium, and coarse grinds, making a clear definition of PS difficult between cereal grains and different mills. Healy et al. (1994) fed weanling pigs ground corn, hard endosperm sorghum, or soft endosperm sorghum in pelleted form, though PS definition was left unclear. The authors found piglets fed the corn treatment had 6% better FC and 23% better BWG than pigs fed either sorghum based diets and found PS to be most influential for the first two weeks of life with the most reduced PS (300 µm) being most beneficial to piglet growth. Pigs prefer greater PS with increasing age but have been found to perform better, no matter age, with finer ground feed, even though more finely ground feed has also been found to produce gastric ulcers. In swine, as fine feed becomes more fluid when combined with digestive juices than coarse feed, the possibility of ulceration increases greatly as PS dips below 500 µm (Goodband et al., 2002). 13

27 Live Production and Mill Mechanic Synchronicity Reducing feed ingredients to their desired PS is the second most expensive operation in a mill after the cost of pelleting (Reece et al., 1985) and the greatest cost in all mash layer diets (Deaton et al., 1988). Finely ground feed has a greater chance to hang up in bulk bins and conveyance equipment, decreasing flowability, and increasing dustiness (Goodband et al., 2002). While there may be live performance gains made with finer corn PS, there is also great savings in more coarsely ground corn, as energy and mechanical cost put forth by the feed mills could outweigh the benefits seen from finely ground corn included into diets. In addition, reduced hammer mill energy consumption and increased production rate is realized when grinding whole grains to a coarser PS. The same theme can be seen in swine production, where pigs fed grain ground to a GMD 500 µm had a 6% improvement in FC compared to pigs fed 900 µm GMD ground grain, and tonnes of feed ground/hr was severely reduced by 43% when decreasing PS from 900 µm to 500 µm (Goodband et al., 2002). While grinding corn or other cereal grain to a finer PS results in greater energy costs, lower throughput, as well as an increased feed cost, Reece et al. (1986b) reported increasing hammer mill screen size from 4.76 mm to 6.35 mm could result in an energy cost saving of 27%. Martin (1985) determined the fineness of corn ground has no effect on rate or energy consumed during the pelleting process. While broilers and pullets are still in growing phases of life, a more finely ground PS with greater BW or BWG later in life, once bones and organs are fully grown, finer cereal PS may be unnecessary for improved live bird performance and does not outweigh feed manufacturing costs. 14

28 REFERENCES Amerah, A. M., V. Ravindran, R. G. Lentle, and D. G. Thomas Feed particle size: Implications on the digestion and performance of poultry. Worlds. Poult. Sci. J. 63: Amerah, A. M., V. Ravindran, R. G. Lentle, and D. G. Thomas Influence of feed particle size on the performance, energy utilization, digestive tract development, and digesta parameters of broiler starters fed wheat- and corn-based diets. Poult. Sci. 87: ASABE Method of determining and expressing fineness of feed materials by sieving: American Society of Agricultural and Biological Engineers S319.4 Feb 2009 (Rev. 2012). American Society of Agricultural and Biological Engineers, St. Joseph, MI. Behnke, K. C Feed manufacturing technology: Current issues and challenges. Anim. Feed Sci. Technol. 62: CPM Economics of grinding for pelleted feeds. California Pellet Mill. Available at of Grinding for Pelleted Feeds.pdf (verified 1 July 2017). Carré, B Effets de la taille des particules alimentaires sur les processus digestifs chez les oiseaux d élevage. INRA Prod. Anim. 13: Carré, B., N. Muley, J. Gomez, F.-X. Oury, E. Laffitte, D. Guillou, and C. Signoret Soft wheat instead of hard wheat in pelleted diets results in high starch digestibility in broiler chickens. Br. Poult. Sci. 46: Deaton, J. W., B. D. Lott, and J. D. Simmons Hammer mill versus roller mill grinding of corn for commercial egg layers. Poult. Sci. 1: Denbow, D. M Gastrointestinal Anatomy and Physiology. Pages in Sturkie s Avian Physiology. Fifth Ed. Academic Press, Cambridge, MA. 15

29 Donohue, M., and D. L. Cunningham Effects of grain and oilseed prices on the costs of US poultry production. J. Appl. Poult. Res. 18: Engberg, R. M., M. S. Hedemann, and B. B. Jensen The influence of grinding and pelleting of feed on the microbial composition and activity in the digestive tract of broiler chickens. Br. Poult. Sci. 43: Frikha, M., H. M. Safaa, M. P. Serrano, E. Jiménez-Moreno, R. Lázaro, and G. G. Mateos Influence of the main cereal in the diet and particle size of the cereal on productive performance and digestive traits of brown-egg laying pullets. Anim. Feed. Sci. Tech. 164: Goodband, R. D., M. D. Tokach, and J. L. Nelssen The effects of diet particle size on animal performance. Kansas State Univ. Agricultural Experiment Station and Cooperative Extension Service, Manhattan, KS. MF-2050:1-6. Hamilton, R. M. G., and F. G. Proudfoot Effects of ingredient particle size and feed form on the performance of Leghorn hens. Can. J. Anim. Sci. 75: Healy, B. J., J. D. Hancock, G. A. Kennedy, P. J. Bramel-Cox, K. C. Behnke, and R. H. Hines Optimum particle size of corn and hard and soft sorghum for nursery pigs. J. Anim. Sci. 72: Hy-Line Hy-Line W-36 Commercial Layer Management Guide Available at (verified 7 January 2016). Koch, K Hammer mills and roller mills. Kansas State Univ. Agricultural Experiment Station and Cooperative Extension Service, Manhattan, KS. MF-2048:1-5. Leeson, S., L. Caston, and J. D. Summers Layer performance of four strains of Leghorn pullets subjected to various rearing programs. Poult. Sci. 76:1 5. Leeson, S., and J. D. Summers Influence of nutritional modification on skeletal size of Leghorn and broiler breeder pullets. Poult. Sci. 63:

30 Martin, S. A Comparison of hammer mill and roller mill grinding and the effect of grain particle size on mixing and pelleting. MS Thesis. Kansas State Univ., Manhattan, KS. Milanovic, S Literature review on the influence of milling and pelleting on granulation and physical characteristics, and production cost of pelleted poultry feed. MS Thesis. Norwegian University of Life Sciences, Postboks 5005, Norway. Morgan, R., and B. Heywang A comparison of a pelleted and unpelleted all-mash diet for laying chickens. Poult. Sci. 20: Nir, I., R. Hillel, I. Ptichi, and G. Shefet Effect of particle size on performance. 3. Grinding pelleting interactions. Poult. Sci. 74: Nir, I., R. Hillel, G. Shefet, and Z. Nitsan. 1994a. Effect of grain particle size on performance: 2. Grain texture interactions. Poult. Sci. 73: Nir, I., G. Shefet, and Y. Aaroni. 1994b. Effect of particle size on performance: 1. Corn. Poult. Sci. 73: Péron, A., D. Bastianelli, F. X. Oury, J. Gomez, and B. Carré Effects of food deprivation and particle size of ground wheat on digestibility of food components in broilers fed on a pelleted diet. Br. Poult. Sci. 46: Portella, F. J., L. J. Caston, and S. Leeson Apparent feed particle size preference by broilers. Can. J. Anim. Sci. 68: Reece, F. N., B. D. Lott, and J. W. Deaton The effects of feed form, grinding method, energy level, and gender on broiler performance in a moderate (21 C) environment. Poult. Sci. 64: Reece, F. N., B. D. Lott, and J. W. Deaton. 1986a. The effects of hammer mill screen size on ground corn particle size, pellet durability, and broiler performance. Poult. Sci. 65: Reece, F. N., B. D. Lott, and J. W. Deaton. 1986b. Effects of environmental temperature and corn particle size on response of broilers to pelleted feed. 65:

31 Safaa, H. M., E. Jimenez-Moreno, D. G. Valencia, M. Frikha, M. P. Serrano, and G. G. Mateos Effect of main cereal of the diet and particle size of the cereal on productive performance and egg quality of brown egg-laying hens in early phase of production. Poult. Sci. 88: Taylor, R. D., and G. P. D. Jones The incorporation of whole grain into pelleted broiler chicken diets. II. Gastrointestinal and digesta characteristics. Br. Poult. Sci. 45: Tollenaar, M., and L. M. Dwyer Physiology of Maize. Pages in Crop Yield: Physiology and Processes. Smith, D.L., Hamel, C., eds. 1st Ed. Springer, Berlin, Germany. Wang, S., W. Chen, H. X. Zhang, D. Ruan, and Y. C. Lin Influence of particle size and calcium source on production performance, egg quality, and bone parameters in laying ducks. Poult. Sci. 93:

32 Chapter 3 CORN PARTICLE SIZE SEPARATION AND HAMMER MILL PERFORMANCE ABSTRACT Ground corn of different geometric mean diameters (GMD) was utilized for a mash fed broiler digestibility study, a crumbled and pelleted floor pen broiler study, a mash fed pullet and subsequent hen study. Corn particle size (PS) treatments (600, 900, 1200, or 1500 µm) were ground and delivered in totes at one of two different intervals (Delivery 1 and Delivery 2) and analyzed for nutrients in triplicate and PS distribution in percentage using the ASABE procedure S319.4 to calculate the GMD and geometric standard deviation (GSD). Energy expenditures from the feed mill (Wenger Feeds, LLC, Rheems, PA) were analyzed for electrical usage put forth from the hammer mills used to grind the corn to each given PS treatment. Measurements included power, amperage of the motors using during grinding, rate at which corn was ground in tonnes/hr (TPH), efficiency, cost ($/tonne and $/KWhr), and speed of (hr/tonne) grinding. Economic analysis showed a linear trend with reduced energy cost and higher TPH with greater PS. The GMD was found to fall within 250 µm of the goal PS for all treatments and both deliveries and GSD was decreased for Delivery 2 compared to Delivery 1 ( vs ). Based on the results of energy usage, TPH, rate, and consistency, feed mills would benefit from a larger grind of corn in poultry diets whenever possible. Further exploration into the effects of varying corn PS on poultry performance will follow. 19

33 INTRODUCTION Soybean meal is utilized as the predominant protein ingredient in the United States, however, because it is pre-processed before entering the mill, feed mills have little control over its PS. However, feed mills have greater control over energy ingredients such as maize, wheat, barley and other cereal grains. These can be ground at the feed mill and vary based on the PS goal of the mill. By identifying an optimum corn PS for a given sector of poultry production, there is an opportunity to maximize feed efficiency and nutrient absorption for broilers, pullets, and layers (CPM, 2017). Two types of equipment are commonly used to reduce PS; hammer mill and roller mill. Generally, the hammer mill is used more frequently because of lower maintenance costs and a simpler user interface. Hammer mills consist of flailing metal rods, swinging in a chamber forcing the grains into and thorough a screen of a given size. On the other hand, roller mills have one or more sets of horizontal rollers with the distance between rollers adjusted to arrive at the desired PS. Due to constant pressure between the rollers, grain size tends to be more uniform (Amerah et al., 2008). The fineness of dietary cereal grain PS plays a large role in pellet quality and bird performance. Poor pellet quality resulting from improper PS cereals decreases the benefits broilers receive from the pelleting process. Additionally, different cereal grains have unique PS that is achieved with a given screen size (Amerah et al., 2007), indicating that even with a specific PS goal, mills likely will need to adjust their roller or hammer mills when using different cereal grains for accurate PS realization. Broiler and layers alike have been shown to have a preference for greater PS as the bird grows with age (Portella et al., 1988). Furthermore, PS has been shown to be more important when in mash diets rather than as crumbles or pellets (Nir et al., 1995; Péron et al., 2005), but there is also the question as to whether the PS is further reduced during the pelleting process as 20

34 there are conflicting reports regarding this process. One study by Péron et al. (2005), showed the distribution of particles between differing grinds of wheat remained consistent both before and after pelleting, while other studies (Engberg et al., 2002; Amerah et al., 2008) reported pelleting nullified the effects of the original particle sizes between treatments of ground wheat. When Amerah et al. (2008) compared wheat and corn, ground to both fine and coarse PS (297 and 528 µm, respectively), then pelleted and fed to male broilers through 21 days of age, the results still revealed PS distribution differences after pelleting. The coarse grinding of the pelleted corn diet improved BWG compared to the finely ground, pelleted corn diet (Amerah et al., 2008). These results would suggest there s an opportunity to target corn PS for a specific age, type of bird, and form of feed to optimize bird performance. Work on PS in other species has shown similar results. Healy et al. (1994) found weanling pigs had greater need for a finer particle size during the first two weeks post-weaning then PS increases with age. Milling energy utilized will be greatly affected by the PS goal, thereby allowing a potential cost savings in milling and poultry feed fabrication. MATERIALS AND METHODS Corn Milling and Economics Wenger Feeds, LLC (Rheems, PA) ground whole corn into four treatment PS (600, 900, 1200, and 1500 µm) at their Muncy, PA mill in two deliveries (Delivery 1 was received at Penn State s Poultry Education Research Center in February 2016, Delivery 2 was received in October 2016). Both Delivery 1 and Delivery 2 were ground using two hammer mills (both Sprout, model #3818), one fitted with a cm diameter coarse grind screen hole, and the other with a cm diameter screen hole for the medium grind. The medium grind hammer mill was used to grind 21

35 the 600 µm and 900 µm, with a 150-HP variable frequency drive (VFD) running at a maximum of 1800 revolutions per minute (RPM). The 1200 µm and 1500 µm corn were ground on the coarse hammer mill, with a 100-HP motor and the VFD at a maximum of 1200 RPM. The use of the VFD allows the mill to fine tune the PS. Wenger Feeds, LLC collected and recorded information regarding the speed and amperage of the two respective hammer mill motors during the grinding, as well as throughput in tonnes per hr (TPH), efficiency (KWh/tonne), cost per KWhr and cost ($/tonne) and speed (hr/tonne) to grind whole corn to the different GMD reported in Table 3-1. It should be noted that all values were calculated with the exception of TPH, which was provided by Wenger Feeds, LLC as estimates from their feed processing. Therefore, TPH values remain unchanged through Table 3-1 for this reason. Sieving and Calculations To determine the actual PS distribution of the 600, 900, 1200, and 1500 µm corn, three samples were taken of each corn treatment from each Delivery (1 & 2) from random locations in the 454 kg totes delivered from Wenger Feeds, LLC (Rheems, PA). The sieving and PS measurements for all samples were measured in accordance with ASABE (2013) procedures. Using a W.S. Tyler sieve shaker (W.S. Tyler Company, Cleveland, OH) in Penn State University s Department of Agricultural and Biological Engineering, each of the four corn treatments were separated into three replicates of 100 g each, for a total of twenty-four 100 g samples. Samples were shaken for 10 minutes each, with one additional minute until there was less than a 0.1% mass change on the smallest screen. All tare weights of individual sieves were taken before shaking, and at the conclusion of sieving. The mass of each of the sample materials were recorded, and percent distribution was calculated, as shown in Tables 3-2 and 3-3. Percent separation between treatments from Delivery 1 and Delivery 2 are shown in Figure 3-1, 3-2, 3-3, 22

36 and 3-4. The following set of calculations (ASABE, 2013) were used to determine mean diameter, where d gw is the geometric mean diameter of all particles by mass (1), S log is the log of the mean diameter of all particles and stands for the geometric standard deviation of lognormal distribution (2), and S gw calculates the geometric standard deviation (GSD) of all particle diameters by mass (3), with final geometric mean diameter (GMD) and standard deviation shown in Table 3-4. In this case, GSD measures the amount of dispersion around the GMD. (1) d gw = log 1 [ (2) S log = [ n i=1 n i=1 (W i log d i) n ] i=1 W i W i(log d i log d gw ) 2 n ] i=1 W i 1 2 = S ln 2.3 (3) S gw 1 2 d gw [log 1 S log (log 1 S log ) 1 ] Statistical Analysis Percent distributions between given screen sizes for all treatments were analyzed using the PROC GLM procedure SAS 9.4 (SAS Institute, 2013) with Tukey s test for multiple means comparison with application of an arcsine transformation on all percentage data and significance determined at a threshold of P 0.05 (Steel and Torrie, 1960). Nutrient Analysis Due to the duration of time between the dietary studies, there was the need to have two batches of corn delivered. Corn treatments for the broiler digestibility, pullet and hen studies were 23

37 delivered as ground corn only to fabricate mash diets, whereas the corn utilized for the broiler floor pen study was delivered as complete crumbled and pelleted commercial diets for each corn PS treatment. The corn delivered in February of 2016 (Delivery 1), was used for the broiler digestibility and pullet growth studies. The corn delivered in October of 2016, (Delivery 2), was used for the hen and floor pen broiler studies. The corn for the broiler floor pen study was mixed, pelleted, and crumbled by Wenger Feeds, LLC (Rheems, PA). Corn samples from Delivery 1 and 2 were analyzed separately for proximate analysis, amino acid concentration (ESCL, Columbia, MO), and mineral concentration in triplicate for feed formulation purposes (Agricultural Analytical Laboratory, University Park, PA) and shown in Table 3-5. RESULTS AND DISCUSSION Feed milling energy usage, efficiency, and economics for all four treatments (600, 900, 1200, and 1500 µm) for Delivery 1 and 2 provided by Wenger Feeds, LLC (Rheems, PA) are shown in Table 3-1. Delivery 1 was similar to Delivery 2, and treatments were ground using the same equipment for both Deliveries. By using the VFD on the hammer mills, power is slightly variable between deliveries, and Delivery 2 corn required more greater power for all treatments compared to Delivery 1. This same trend is also reflected in efficiency and cost with Delivery 2 being slightly less efficient and costlier than Delivery 1 ($0.51/tonne vs. $0.49/tonne for the 600 µm treatment). Both Delivery 1, 2, and the average of both deliveries show clear linear trends for increased TPH as corn PS increases. Efficiency, cost/tonne, and hr/tonne all decrease linearly as corn PS increases. The type of grain used with a specific hammer mill setting and screen has been shown to influence the PS distribution produced, as previous work has shown corn and wheat run though the same 1- and 7-mm hammer mill screens produce different results, where corn resulted 24

38 in a GMD of 297 µm and 528 µm, and wheat resulted in 284 µm and 890 µm PS, respectively (Amerah et al., 2007, 2008). Delivery 1 and 2 were evaluated separately for PS percent separation using the same stack of sieves required for the ASABE procedure S319.4 to keep all measurements as standardized as possible. Delivery 1, shown in Table 3-2, revealed the 3360 and 2380 µm screens held the greatest percent (53.28%) of 1500 µm corn compared to 600, 900, and 1200 µm treatment corn, while the remaining screens held no more than 13.89% each. Screen size 1680 µm interestingly was greatest for the 900 µm treatment corn, followed by the 600 µm corn, then the 1500 µm and the 1200 µm corn. Screen openings 1190, 841, and 595 µm were not significantly different between the 1200 and 1500 µm treatment corn. Delivery 2, shown in Table 3-3, revealed the 3360, 2380, and 1680 µm screens held significantly more of the 1500 µm corn (60.66%) than all other treatments. Screens 1190, 841, 595, and 420 µm held the greatest portion of the 600 µm corn (50.22%) compared to the 900, 1200 and 1500 µm treatments. At the 420 µm screen size, the 900 and 1200 µm screens held an intermediate amount of corn and were not significantly different from each other (12.50 and 9.76%, respectively) compared to the 600 and 1500 µm treatments. Screens 149, 105, 74, and 52 µm were not significantly different between treatments and all screens in the range held between 3.18% % of the total 100 g, though the 600 µm corn treatment also had significantly more fines in the bottom pan compared to all other treatments (0.08 vs. 0.02, 0.02, and 0.01%). Figures 3-1, 3-2, 3-3, and 3-4 compare screen distribution between the two deliveries for each corn treatment (600, 900, 1200, and 1500 µm). In both Delivery 1 and 2, the 600 and 900 µm corn treatments track together, as do the 1200 and 1500 µm corn treatments. The comparison between Delivery 1 and Delivery 2 for the 600 µm corns (shown in Figure 3-1) reveals Delivery 1 had a greater percentage of corn remaining in screens measuring 2380 µm and 1680 µm, whereas Delivery 2 had a greater percentage of corn remaining in screens measuring 595 µm and 420 µm. 25

39 The 900, 1200, and 1500 µm treatments (Figures 3-2, 3-3, and 3-4) tracked very similarly between Delivery 1 and Delivery 2 using the same procedure. Geometric mean diameter and GSA were calculated and shown for all corn treatments and both deliveries in Table 3-4. Within treatment and between Deliveries, GMDs for the 600 µm treatment were very close at and µm, yet approximately µm away from the target PS of 600 µm. All corn treatments were within 250 µm of the goal PS of the current study. The 900 µm calculated GMD values were very close, within 66 µm of each other in Delivery 1 and 2, and closely flanked the 900 µm target treatment. Delivery 1 and 2 GMD values for the 1200 µm treatment were within 26 µm of each other though were slightly lower than the goal of 1200 µm. Delivery 1 and 2 GMD were higher than the 1500 µm target, where Delivery 2 was within 60 µm of the goal and Delivery 1was 214 µm greater than the 1500 µm target. Likewise, GSD were very low herein compared to Reece et al. (1985) where roller mill (2.23 GSD) and hammer mill (2.35 GSD) ground corn were compared. Treatment corn from both Delivery 1 and Delivery 2 were both analyzed for proximate nutrients (crude protein, ether extract, crude fiber, ash and dry matter), along with amino acid (AA) and mineral concentrations (Table 3-5). These were necessary for accurate feed formulation of the respective studies. Delivery 1 and Delivery 2 corns were approximately 100 Kcal/kg different in metabolizable energy (ME) ( vs Kcal/kg) and crude protein (CP) (7.75 vs. 7.56%). Delivery 1 corn showed lower ether extract (EE) and greater percent ash compared to Delivery 2 corn (1.76 vs. 3.69% EE; 2.40 vs. 1.45% ash) which impacted their final ME values. The reduced percent ash in Delivery 2 reflects clearly onto the lower calcium, iron, manganese, and zinc levels in Delivery 1 corn and are reflected in the lower ash content, where calcium of Delivery 2 corn is 0.09% vs. Delivery 1 corn at 0.42%, and iron was mg/kg in Delivery 2 corn versus mg/kg in Delivery 1 corn. Manganese, similarly, was decreased for Delivery 2 corn at mg/kg versus mg/kg in Delivery 1 corn. Lastly, zinc shows the 26

40 same trend as the previous minerals, with Delivery 2 zinc reduced at mg/kg versus mg/kg in Delivery 1 corn. Any variations in nutrient density of Delivery 1 and 2 corn may have varied due to growing region, as well as a potential of soil contaminated corn in Delivery 1. Sieving of the corn clearly showed the treatment separation of PS as planned for the study, with very close GMD to the set goal, and low accompanying GSD values, within Less amperage, power, and cost were associated with greater feed TPH for the larger PS corn. There was a very linear response, with smaller particle corn having less TPH and greater associated cost and time needed to grind compared with larger PS having greater TPH and less grinding cost and time required. Hammer mill grinding is normally less uniform compared to roller mill grinding. The results herein indicated the GSD to be less than Differences in VFD motor speed, screen size, along with percent moisture of corn could potentially affect the final product. Energy expenditures from the feed mill strongly indicate that the energy costs associated with PS reduction could be of as a source of cutting costs without negatively affecting bird performance. ACKNOWLEDGEMENTS This study was funded through the 2015 Pennsylvania Poultry Industry Egg and Broiler Research Check-off Program. REFERENCES Amerah, A. M., V. Ravindran, R. G. Lentle, and D. G. Thomas Feed particle size: Implications on the digestion and performance of poultry. Worlds. Poult. Sci. J. 63:

41 Amerah, A. M., V. Ravindran, R. G. Lentle, and D. G. Thomas Influence of feed particle size on the performance, energy utilization, digestive tract development, and digesta parameters of broiler starters fed wheat- and corn-based diets. Poult. Sci. 87: ASABE Method of determining and expressing fineness of feed materials by sieving: American Society of Agricultural and Biological Engineers S319.4 Feb 2009 (Rev. 2012). St. Joeseph, MI. CPM Economics of grinding for pelleted feeds. Available at of Grinding for Pelleted Feeds.pdf. Engberg, R. M., M. S. Hedemann, and B. B. Jensen The influence of grinding and pelleting of feed on the microbial composition and activity in the digestive tract of broiler chickens. Br. Poult. Sci. 43: Healy, B. J., J. D. Hancock, G. A. Kennedy, P. J. Bramel-Cox, K. C. Behnke, and R. H. Hines Optimum particle size of corn and hard and soft sorghum for nursery pigs. J. Anim. Sci. 72: Nir, I., R. Hillel, I. Ptichi, and G. Shefet Effect of particle size on performance. 3. Grinding pelleting interactions. Poult. Sci. 74: Péron, A., D. Bastianelli, F. X. Oury, J. Gomez, and B. Carré Effects of food deprivation and particle size of ground wheat on digestibility of food components in broilers fed on a pelleted diet. Br. Poult. Sci. 46: Portella, F. J., S. Leeson, and L. J. Caston Apparent feed particle size preference by laying hens. Can. J. Anim. Sci. 68: Reece, F. N., B. D. Lott, and J. W. Deaton The effects of feed form, grinding method, energy level, and gender on broiler performance in a moderate (21 C) environment. Poult. Sci. 64: SAS Institute SAS User s Guide: Version 9.4. Cary, NC. Steel, R. G. D., and J. H. Torrie Principles and procedures of statistics, a biometrical approach. McGraw-Hill Kogakusha, Ltd., Tokyo, Japan. 28

42 Table 3-1. Hammermill economic cost (average amperage, power, TPH, efficiency, cost/tonne & hr/tonne) Delivery 1 Treatment Avg. Power TPH Efficiency USD$/tonne amperage (KW) (tonnes/h) (KWhr/tonne) ($0.0739/KWhr) hr/tonne 600 µm µm µm µm Delivery 2 Treatment Avg. Power TPH Efficiency USD$/tonne amperage (KW) (tonnes/h) (KWhr/tonne) ($0.0739/KWhr) hr/tonne 600 µm µm µm µm Average of Deliveries 1 & 2 Treatment Avg. Power TPH Efficiency USD$/tonne amperage (KW) (tonnes/h) (KWhr/tonne) ($0.0739/KWhr) hr/tonne 600 µm µm µm µm

43 Table 3-2. Corn particle size distribution: Percent separation (%) Delivery 1 1,2 Treatment 600 µm 900 µm 1200 µm 1500 µm SEM P-value Screen size c 0.75 c b a 2.76 < d c b a 2.86 < b a d c 0.79 < a b 9.53 c 9.51 c 1.01 < a b 6.38 c 5.79 c 0.73 < a 8.37 a 5.26 b 4.09 b 0.64 < a 7.62 a 4.35 b 2.92 c 0.62 < a 6.39 a 6.66 a 2.47 b a a 9.42 a 2.09 b 1.11 < a 3.57 ab 3.56 b 1.51 b a 3.41 b 4.13 b 2.95 b ab 0.13 b 0.37 ab 0.62 a b 0.08 b 0.11 b 0.47 a Bottom Pan b 0.05 b 0.13 b 0.41 a a-d Means within the same column with no common superscript differ significantly (P 0.05). 1 All corn analyses were done in triplicate with the shaker running for 11 minutes per sample. 2 All samples for each treatment and Delivery were analyzed in triplicate. 3 Screens were measured in µm per internal screen hole diameter. 4 Bottom pan catches any remaining fines that were shaken to the bottom of the stack. 30

44 Table 3-3. Corn particle size distribution: Percent separation (%) Delivery 2 1,2 Treatment 600 µm 900 µm 1200 µm 1500 µm SEM P-value Screen size c 0.47 c 5.02 b a 1.53 < d 7.82 c b a 3.50 < b a a a 1.16 < a a a b a b 9.25 c 7.09 d 0.95 < a b 7.40 c 5.43 c 1.68 < a ab 9.76 ab 4.44 b ab a 5.49 b 4.96 b a 6.75 a 5.43 ab 3.14 b Bottom Pan a 0.02 b 0.02 b 0.01 b a-d Means within the same column with no common superscript differ significantly (P 0.05). 1 All corn analyses were done in triplicate with the shaker running for 11 minutes per sample. 2 All samples for each treatment and Delivery were analyzed in triplicate. 3 Screens were measured in µm per internal screen hole diameter. 4 Bottom pan catches any remaining fines that were shaken to the bottom of the stack. 31

45 Amount (%) Delivery 1 Delivery Screen Size (µm) Figure 3-1. Corn particle size percent separation: 600 µm Delivery 1 vs. Delivery 2 32

46 Amount (%) Delivery 1 Delivery Screen Size (µm) Figure 3-2. Corn particle sieving percent separation: 900 µm Delivery 1 vs. Delivery 2 33

47 Amount (%) Delivery 1 Delivery Screen Size (µm) Figure 3-3. Corn particle sieving percent separation: 1200 µm Delivery 1 vs. Delivery 2 34

48 Amount (%) Delivery 1 Delivery Screen Size (µm) Figure 3-4. Corn particle sieving percent separation: 1500 µm Delivery 1 vs. Delivery 2 35

49 Table 3-4. Corn treatment particle size sieving: GMD and GSD 1,2 Delivery 1 Treatment GMD (µm) ± GSD 600 µm ± µm ± µm ± µm ± 0.41 Delivery 2 Treatment GMD (µm) ± GSD 600 µm ± µm ± µm ± µm ± Geometric standard deviation (GSD) is defined as the standard deviation of log-normal distribution by mass in tenbased logarithm (ASABE Standard S319.4, 2013). 2 All samples for each treatment and Delivery were analyzed in triplicate. 36

50 Table 3-5. Nutrient composition of corn ( as is basis) 1 Delivery 1 Delivery 2 Nutrient (%) ME (Kcal/kg) NFE Dry matter Crude protein Ether extract Crude fiber Ash Amino acids (%) Aspartic Acid Threonine Serine Glutamic Acid Proline Glycine Alanine Cysteine Valine Methionine Isoleucine Leucine Tyrosine Phenylalanine Lysine Histidine Arginine Mineral (%) 3 Calcium Total phosphorus Potassium Magnesium Sulfur Sodium (mg/kg) Iron (mg/kg) Copper (mg/kg) Manganese (mg/kg) Zinc (mg/kg) All samples for each treatment and Delivery were analyzed in triplicate. 2 Corn was donated by cooperator Wenger Feeds, LLC (Rheems, PA) and nutrient values were analyzed by ESCL (Columbia, MO). ME (kcal/kg) was calculated using the NRC (1994) equation x CP x EE x NFE (for corn grain). 3 Nitrogen free extract (NFE) was calculated using the equation NFE = DM - Ash - CP - CF EE (National Research Council, 1994). 4 Mineral values were obtained from the Agricultural Analytical Laboratory at The Pennsylvania State University (University Park, PA). 37

51 Chapter 4 EFFECT OF CORN PARTICLE SIZE ON APPARENT AND TRUE ILEAL DIGESTABILITY AND JEJUNUM VISCOSITY OF 35-DAY OLD MALE BROILERS ABSTRACT Corn particle size (PS) treatments were compared utilizing digestibility, feed intake, growth, and conversion of broiler chickens. Day old Cobb-500 male broilers (196) were placed into 17 battery cages with birds per cage. Birds were fed a standard starter and grower diet to 29 d. At 14 days of age, birds were redistributed into 35 battery cages with 5 birds per cage for the corn particle size treatment diets and 8 birds per cage for the protein-free (PF) diet. From days birds transitioned to one of the five treatment diets comprised of (600 µm, 900 µm, 1200 µm, or 1500 µm PS corn, or PF). The PF diet contained only dextrose monohydrate as the sole energy source. At 35 d birds were euthanized and ileal and jejunum portions of the intestine were harvested for apparent, true and standardized digestibility determination. All data was analyzed using a one-way ANOVA with the mixed procedure of SAS 9.4 and Tukey s range test for means comparison when necessary. There were significant differences (P < 0.05) between treatments at 35 d for body weight (BW) and d body weight gain (BWG). Apparent digestibility of Met, Lys, Ile, Pro, Tyr, and Gly were significantly less for broilers fed 600 µm and compared to the other PS. True digestibility yielded no statistically significant results, but with standardized endogenous losses from the literature, Met digestibility was again decreased for broilers fed the 600 µm test feed. Jejuna digesta viscosity, measured in centipoise, was highest among birds fed the 600 and 900 µm PS. In conclusion, PS influences broiler growth performance and at 35 d 38

52 larger particles in a mash diet lend themselves to greater apparent and true digestibility, less viscous digesta, allowing better gastrointestinal tract flow, improved nutrient uptake and, as a result, better live performance. INTRODUCTION In the United States, a standard broiler diet consists of approximately 60% corn (Leeson and Summers, 2005), however prices have been increasing and availability has been decreasing over the past decade as ethanol production has taken from 10% to 30% of the US corn crop (Donohue and Cunningham, 2009). To continue raising broilers for United States consumers and to increase production in the future as the world population continues to rise, there is a need to hone in on an optimum corn particle size (PS) to allow for greater bird efficiency with the US corn available to feed mills. Previous work has shown pellet processing can further reduce particle size, as larger particles tend to be broken between pellet rollers and the die (Engberg et al., 2002; Péron et al., 2005). No differences were seen in bird performance when the pelleting process evened out differences in wheat particle size in the study by Engberg et al. (2002). In mash form, larger feed particles are more easily consumed as birds age due to beak size (Morgan and Heywang, 1941). Beak size and gape has been shown to influence PS preference in broilers. Previous work by Portella et al. (1988) has shown broilers choose feed based solely on particle size and the more uniform a diet is, the less time a bird will spend searching for larger, less uniform particles (Nir et al., 1994a). Additionally, as a birds gape increases with age, chickens have been found to prefer larger feed particles as well. The same study also reported 21 day old birds fed medium or coarse mash diets had improved BW and BWG over those fed a finely ground mash diet (Nir et al., 1994b). As poultry nutritionists are able to feed with greater precision, it becomes increasingly 39

53 important to accurately measure apparent ileal digestibility (AID) and true ileal digestibility (TID) of not only ingredients but also the particle size of corn and other cereals, as varying geometric mean diameter (GMD) has been shown to influence nutrient utilization and growth performance (Reece et al., 1985, 1986). Varying corn PS affects broiler growth performance and apparent and true ileal digestibility. MATERIALS AND METHODS Birds and Housing Day old male Cobb 500 broiler chicks (196) were obtained from a local hatchery (Elizabethtown, PA). Chicks were randomly placed into 17 battery cages with birds per cage ( cm 2 /bd). At 14 days of age, birds were redistributed into 35 battery cages with 5 birds per pen for all corn diets and 8 birds per cage for the PF diet, with 7 replicate cages for each treatment ( cm 2 /bd). All management practices were maintained throughout the study as recommended by Cobb-Vantress (2012). The room s temperature began at 32.2 C at day 0 of the study, and was gradually decreased to 21.1 C by day 14 where it remained for the duration of the study. Birds were fed a commercial starter diet from day 0-14 and a commercial grower from day 14-28, and were transitioned to the treatment diets (33% treatment diet, 66% control) on day 29, and day 30 (66% treatment diet, 33% control) and fed 100% treatment diets from day On day 28, before beginning transition to treatment diets, birds were weighed individually and redistributed as necessary to achieve a uniform body weight between replicate treatment cages. All birds were provided water ad libitum and feed according to the procedure below. All techniques and procedures involving the birds in this study were approved by The Pennsylvania State University Institutional Animal Care and Use Committee (IACUC Protocol #46838). 40

54 Treatment Diet Formulation for the Digestibility Assay All corn dietary treatments contained g/kg of the test ingredient, as either 600, 900, 1200, or 1500 μm PS corn (Table 4-1). The PF diet was formulated with dextrose monohydrate (My Spice Sage, Yonkers, NY) as the only carbohydrate source (84.34%) and was included at 5% in all corn diets. All diets were formulated to contain 2% Celite (Sigma-Aldrich Co., St. Louis, MO), which was mixed at a 2:3 ratio of Celite 110 and 281, 0.80% vitamin and trace mineral premix, and 0.50% salt. To keep all treatment diets at the same percent calcium and phosphorus levels, limestone was added to all corn diets at 0.61% and the PF diet at 1.37% and di-calcium phosphate was added to the corn diets at 1.55%, and the PF diet at 1.99%. Additionally, both diets included corn oil at 3.8% for the corn diets and 6.0% for the PF, and the PF diet also included 3.0% cellulose. Upon analysis, each respective corn treatment diet (600, 900, 1200, or 1500 μm) averaged 7.25, 7.56, 7.78, and 7.94% crude protein (CP), for 600, 900, 1200, and 1500 μm, respectively, and a calculated metabolizable energy (ME) of 3,274 kcal/kg. All analyzed amino acids (AA) were similar across corn treatment diets, while analyzed AA for the PF diet was zero. Digestibility Assay At 35 days of age, birds were fasted overnight for 8 hours and re-fed their respective treatment diet for 4 hours before being euthanized (Kadim and Moughan, 1997) to improve uniformity of treatment birds and gut fill for the purpose of collecting ileal digesta samples, which were collected from each bird per replicate cage (n = 5 birds/cage for all corn PS treatment cages, and n = 8 for all PF cages) by gently squeezing from the terminal end of the jejunum at Meckel s diverticulum, to approximately ~1 cm proximal to the ileal-cecal junction into a pooled 100 ml sample cup per replicate cage placed on ice. Once transported back to the lab, samples 41

55 were frozen at -20 C until being freeze dried. After freeze drying, samples were thoroughly ground with a mortar and pestle and pooled to achieve a minimum of 10 g per sample for analysis. The yield of dried ileal digesta influenced the number of replicate samples that could be analyzed per treatment (PF, n = 3; 600 μm, n = 4; 900 μm, n = 5; 1200 μm, n = 5; 1500 μm, n = 4). Viscosity Assay Jejuna digesta samples were collected from the end of the duodenal loop to Meckel s diverticulum from each replicate cage (5 birds per cage for all four corn treatments and 8 birds per cage for each PF diet cage) by gently squeezing contents into a pooled sample cup for each replicate cage. Jejuna digesta samples were placed on ice and brought back to the laboratory where they were kept refrigerated until analysis. Each jejuna sample was homogenized using a sterile stirring rod, evenly distributed into two 16 ml Eppendorf tubes with plastic Pasteur pipettes, and then centrifuged at 14,000 revolutions per minute (RPM) at 4 C for 5 minutes. The supernatant liquid (0.5 ml) from the jejuna samples was harvested off the surface and measured using a digital viscometer (Brookfield model DV-II+, Brookfield AMETEK, Inc., Middleboro, MA) at 25 C and a spindle speed of 30 RPM. Each sample was read after 30 seconds. The average viscosity of each pair of Eppendorf tubes (one pair of tubes for each replicate cage) was used as a replicate, with a total of 7 replicate measurements per treatment. Nutrient Analysis of Digesta and Complete Treatment Diets Replicate treatment diets (n = 3) and all pooled freeze-dried ileal samples were analyzed at the ESCL using AOAC (2006) method E (a,b) to measure the complete AA profile with 42

56 the exception of tryptophan and method to determine CP and method (using a vacuum oven) to determine moisture for diets and digesta. Additionally, method was used to determine acid insoluble ash content, method (A) was used to analyze for ether extract (EE) (by ether extract), and crude fiber (CF) was determined by method Calculations Apparent and true ileal amino acid digestibility were calculated on a dry matter (DM) basis according to methods reported by Lemme et al. (2004), Burley (2012), and Li (2015), where diet samples analyzed in triplicate (ESCL, Columbia, MO) and averaged for AA and acid insoluble ash (AIA) were used in the calculation. Measurements of ileal digestibility are used to ascertain estimated AA bioavailability. Apparent ileal digestibility (AID), which measures AA bioavailability as-is from collected bird digesta, and true ileal digestibility (TID), which standardizes AID bioavailability using the ileal endogenous amino acid losses (EAAL) from the PF treatment birds, were calculated for each sample and then averaged for each treatment. By pooling PF bird replicates (n = 3), EAAL were determined by freeze drying samples and analysis at the ESCL using AOAC (2006) method E (a,b) to measure AA concentrations, and AOAC method to determine acid insoluble ash content. All equations below use the following terms: AA diet is the AA concentration (%) in the diet, AA digesta is the AA concentration (%) in the digesta sample, AIA diet is the acid insoluble ash concentration from addition of Celite to the diets, and AIA digesta is the acid insoluble ash concentration from the dietary addition of Celite in the digesta samples, all on a DM basis. Additionally, a second TID (TID Lit ) was calculated using published EAAL values (Lemme et al., 2004) from five replicated, experiments using enzymatically hydrolyzed casein, rather than ones measured herein, called EAAL Lit. The endogenous ileal AA losses (g/100g DM) used to calculate the TID Lit were as 43

57 follows: Met, ; Cys, ; Lys, ; Thr, ; Arg, ; Ile, ; Leu, ; Val, ; His, ; Phe, ; CP, (Lemme et al., 2004). (1) Apparent AA digestibility: AID = ((AIA diet AA digesta )/(AIA digesta AA diet ) 100) (2) Endogenous ileal digesta AA losses from PF diet and digesta AA values (g/ 100 g DM): EAAL = (AA digesta AIA diet )/(AIA digesta ) (3) True AA digestibility (g/100 g DM): TID = [AID + (EAAL/AA diet )] 100 (4) True AA digestibility with EAAL values from the literature (g/100 g DM): TID Lit = [AID + (EAAL Lit /AA diet )] 100 Statistical Analysis Data was analyzed using a one-way ANOVA in the MIXED procedure of SAS software version 9.4 (SAS Institute, 2013) where statistical significance was defined at P 0.05 and differences between treatments were identified using Tukey s test for multiple mean comparisons (Steel and Torrie, 1960). 44

58 RESULTS AND DISCUSSION In this study, four differently ground corn particle sizes were evaluated to determine their impact on digestibility for broilers. Nutrients in the Delivery 1 corn previously described in Table 3-5 (Kitto, 2017), were used exclusively for this study. Both diet formulation and nutrient analysis and AA concentrations of all four treatment diets and the PF diet are shown in Table 4-1. While all four treatment diets were formulated to be isocaloric and isonitrogenous, nutrient analysis shows CP concentrations increasing as PS increases, through all corn treatments. The PF diet had a higher CP level than expected, although similar results have been seen previously in diets which were formulated to be PF (Burley, 2012; Li, 2015). Body weight was not different between treatments at day 28 as birds started the transition from the control diet to their treatment diets (Table 4-2). At day 35 PF birds were significantly lighter than the 600, 900, and 1200 µm corn treatments. Birds fed 1500 µm were not different from the PF or 600 and 900 µm fed birds and the BWG of birds between day 28-35, was significantly greater for the 600, 900, and 1200 µm treatments compared to the 1500 µm and PF. Birds fed the 1500 µm treatment diet were observed to be selecting finer particles from their diets, and leaving the larger particles behind as orts. Portella et al., (1988) has observed reduced BW and BWG when birds spent additional time selecting feedstuffs. Furthermore, selection of small PS may be due to the physical size of the birds as Nir et al. (1994b) noted the small beak and gape of the throat influenced large PS consumption. Lastly, the birds herein were slightly reduced in BW overall compared to the Cobb-500 broiler management guide (Cobb-Vantress, 2012) as the raised wire floor batteries may have impaired growth. Endogenous AA losses (Table 4-3) were calculated from equation (2) above and were found to be far greater, ranging from g/100g DM, than previous work by Burley (2012). As a result of these greater EAAL values, TID calculations resulted in values over 100%. 45

59 The inherently low protein concentration of the corn evaluated herein could explain the TID values and why Burley (2012) did not have TID values over 100%, as the ingredients diets from that study ranged from % CP, whereas the ones used in this study ranged from %. One explanation for TID values greater than 100% can be from higher endogenous AA losses for corn and also its inherent low CP concentration. Past work has noted the same issue when evaluating low CP corn for TID with broilers raised to 21 days of age (Adedokun et al., 2008), Peking ducks raised to 26 days of age (Kong and Adeola, 2013), and in growing pigs (Stein et al., 2005). Furthermore, broilers raised to 5 weeks of age and given a low CP wheat (9.2%) as a test ingredient resulted in TID values over 100% according to Kadim et al. (2002). Previous work from Lemme et al. (2004) indicates that test ingredients naturally low in AA more greatly affect TID calculations than those with inherently high AA concentrations. Endogenous AA losses more greatly influence the TID calculation when AA diet or AA digesta are lower, as with cereal grains or a legume. For example, wheat, with 13% CP can express a difference of 75% AID versus 86% TID, as EAAL values cause overestimation of AA digestibility in those inherently lower AA concentrated ingredients (Lemme et al., 2004). These authors came to the conclusion that low corn CP levels are highly affected by the relative EAAL and results in TID values over 100%. Another possible explanation and one that works in concert with the low corn CP and AA concentrations would be greater EAAL from PF fed birds versus birds fed diets including a test ingredient with adequate levels of protein (Siriwan et al., 1993). Additionally, high endogenous losses could have resulted from too much pressure squeezing the ileum, pushing mucous out along with the digesta and adding to the endogenous losses. Lastly, while previous studies have sampled from the whole ileum without adverse effects, it is possible higher EAAL values come from utilization of the whole ileum (from Meckel s diverticulum to approximately 1 cm proximal to the ileo-cecal junction), rather than utilization of only two-thirds of the ileum 46

60 mostly distal from Meckel s diverticulum. As previous work has shown there are fewer nutrients absorbed in the first third of the ileum posterior to Meckel s diverticulum (Kluth et al., 2005). Apparent ileal AA digestibility calculations from equation (1) and analysis results are shown in Table 4-4. The 600 µm treatment was found to have the lowest AID for Met, Lys, Ile, Pro, Tyr, and Gly. Overall, apparent digestibility ranged from 59.04% (for 600µm Thr) to 87.11% (for 900 µm Met). Ser approached significance with the 900 µm digestibility greater than the other corn treatments at 75.31% AID. When AID was graphed including all the treatment results, a second order polynomial line revealed a strong relationship between PS and AA digestibility with an R 2 value of and the digestibility trend line peak at µm based on the data herein (Figure 4-1). Total ileal AA digestibility was calculated using equation (3), and the EAAL values from the study herein (Table 4-5). The range of TID was from 92.28% for Gly to % for Lys and were not significantly different between treatments for any AA measured, although a repeating numerical trend indicated the 600 µm corn had lower TID values compared to 900, 1200, and 1500 µm PS treatments for both individual AA and overall as was observed for AID. When the TID results were similarly graphed with a second order polynomial line for total AA digestibility had an R 2 value of and a peak value of µm (Figure 4-2) very similar to the AID results shown in Figure 4-1. These results indicate that while there are no significant TID differences between treatments for any AA evaluated, the trend line was highly correlated with the AA digestibility values for each treatment. As previously discussed, because high EAAL values resulted in TID values over 100% in the current study, a set of standardized EAAL values from Lemme et al. (2004) were another approach utilized to calculate TID without concern for high EAAL. As indicated by Lemme et al. (2004), when test ingredients have naturally low CP concentrations, the standardization step calculating TID using EAAL values can greatly overestimate the AA diet and AA digesta. Therefore, the standardized EAAL Lit from Lemme et al. 47

61 (2004) sought to rectify any overestimations caused by this study s EAAL values using values which were repeated five times, using enzymatically hydrolyzed casein (EHC). The TID Lit values were recalculated using EAAL Lit values in equation (4), and results shown in Table 4-6. Results for TID Lit were not significant, save Met, where the 600 µm treatment was reduced compared to the other PS treatments and a (P < 0.10) numerical trend for Lys. Overall values were consistently lower for the 600 µm corn treatment among all AA and for the overall mean compared to the other PS treatments. Figure 4-3, TID Lit, shows this as well, with an R 2 = and second order polynomial trend line indicating the AA digestibility peaked at a PS of µm. The apparent and true ileal AA digestibility peak PS tracked more closely together at and µm, respectively, compared to the literature TID Lit, which peaked at µm. Jejunum digesta viscosity was measured, and the 900 µm treatment was significantly greater than the PF, 1200 and 1500 µm treatments (Table 4-7). The 600 µm viscosity was intermediate and insignificantly different from the other corn PS treatments. Broilers fed finely ground mash feed have historically been found to have lower BWG and FI, possibly due to reduced flow through the gastrointestinal tract caused by high digesta viscosity (Yasar, 2003). Jejunum viscosity measurements were highest for 600 and 900 µm treatments, indicating decreased gastrointestinal movement, nutrient digestibility, and growth. The AID of Met, Lys, Ile, Pro, Tyr, and Gly were decreased for the 600 µm treatment compared to the other PS, and while there were no significant results in TID, the TID Lit evaluation resulted in similar results for Met digestibility compared to the 900, 1200, or 1500 µm. There were significant differences between treatments for BW at 35 days of age, with 1200 µm treatment birds being significantly heavier than 1500 µm or PF birds, which agrees with AID and TID digestibility findings seen in Figure 4-1 and 4-2. While this could be due to the 1500 µm fed birds selectively choosing the finer particles from their mash feed, the results agree with digestibility findings. The day BWG was greater for the 600, 900 and 1200 µm 48

62 treatments and reduced for 1500 µm treatment broilers. The lowest and best viscosity was the 1200 µm treatment which corresponds closely with AID, TID, and TID Lit results, indicating the 1200 µm treatment birds had the highest nutrient absorption between the corn treatments. Body weight and BWG results corroborate viscosity and digestibility results and indicate the 1200 µm corn particle diet allowed growing broilers the most optimum nutrient absorption, growth performance based on jejunum viscosity, AID and TID digestibilities, as well as the best BW and BWG through 35 days of age. For broilers in the later stages of life, these results indicate improved growth and nutrient absorption when fed 1200 µm corn and, when paired with decreased milling costs, the 1200 µm corn treatment may be most beneficial for both mill savings and improved bird performance. ACKNOWLEDEMENTS This study was funded through the 2015 Pennsylvania Poultry Industry Broiler Research Check-off Program. REFERENCES Adedokun, S. A., O. Adeola, C. M. Parsons, M. S. Lilburn, and T. J. Applegate Standardized ileal amino acid digestibility of plant feedstuffs in broiler chickens and turkey poults using a nitrogen-free or casein diet. Poult. Sci. 87: AOAC, Official Methods of Analysis. AOAC Int., Gaithersburg, MD. Burley, H. K Enrichment of methionine from naturally concentrated feedstuffs for use in organic poultry diets. PhD dissertation. Penn State Univ., University Park, PA. 49

63 Cobb-Vantress Cobb 500 Broiler Performance & Nutrition Supplement Guide. Available at guides/cobb500_broiler_performance_and_nutrition_supplement.pdf (verified 2 October 2016). Donohue, M., and D. L. Cunningham Effects of grain and oilseed prices on the costs of US poultry production. J. Appl. Poult. Res. 18: Engberg, R. M., M. S. Hedemann, and B. B. Jensen The influence of grinding and pelleting of feed on the microbial composition and activity in the digestive tract of broiler chickens. Br. Poult. Sci. 43: Kadim, I. T., and P. J. Moughan Development of an ileal amino acid digestability assay for the growing chicken - effects of time after feeding and site of sampling. Brit. Poult. Sci. 38: Kadim, I. T., V. Ravindran, and P. J. Moughan Ileal amino acid digestibility assay for the growing meat chicken - comparison of ileal and excreta amino acid digestibility in the chicken. Brit. Poult. Sci. 43: Kitto Chapter 3. Corn particle separation and hammermill performance. MS. Penn State Univ. University Park, PA. Kluth, H., K. Mehlhorn, and M. Rodehutscord Studies on the intestine section to be sampled in broiler studies on precaecal amino acid digestibility. Arch. Anim. Nutr. 59: Kong, C., and O. Adeola Comparative amino acid digestibility for broiler chickens and White Pekin ducks. Poult. Sci. 92: Leeson, S., and J. D. Summers Commercial Poultry Nutrition. 3rd Ed. Context Products Ltd., Packington, Leicestershire England. Lemme, A., V. Ravindran, and W. L. Bryden Ileal digestibility of amino acids in feed ingredients for broilers. World Poult. Sci. J. 60:

64 Li, S Naturally concentrated methionine-rich feedstuffs for organic broiler production. MS thesis. Penn State Univ. University Park, PA. Morgan, R., and B. Heywang A comparison of a pelleted and unpelleted all-mash diet for laying chickens. Poult. Sci. 20: Nir, I., R. Hillel, G. Shefet, and Z. Nitsan. 1994a. Effect of grain particle size on performance: 2. Grain texture interactions. Poult. Sci. 73: Nir, I., G. Shefet, and Y. Aaroni. 1994b. Effect of particle size on performance: 1. Corn. Poult. Sci. 73: Péron, A., D. Bastianelli, F. X. Oury, J. Gomez, and B. Carré Effects of food deprivation and particle size of ground wheat on digestibility of food components in broilers fed on a pelleted diet. Br. Poult. Sci. 46: Portella, F. J., L. J. Caston, and S. Leeson Apparent feed particle size preference by broilers. Can. J. Anim. Sci. 68: Reece, F. N., B. D. Lott, and J. W. Deaton The effects of feed form, grinding method, energy level, and gender on broiler performance in a moderate (21 C) environment. Poult. Sci. 64: Reece, F. N., B. D. Lott, and J. W. Deaton The effects of hammer mill screen size on ground corn particle size, pellet durability, and broiler performance. Poult. Sci. 65: SAS Institute SAS User s Guide: Version 9.4. Cary, NC. Siriwan, P., W. L. Bryden, Y. Mollah, and E. F. Annison Measurement of endogenous amino acid losses in poultry. Br. Poult. Sci. 34: Steel, R. G. D., and J. H. Torrie Principles and Procedures of Statistics, a Biometrical Approach. McGraw-Hill Kogakusha, Ltd., Tokyo, Japan. 51

65 Stein, H. H., C. Pedersen, A. R. Wirt, and R. A. Bohlke Additivity of values for apparent and standardized ileal digestibility of amino acids in mixed diets fed to growing pigs. J. Anim. Sci. 83: Yasar, S Performance, gut size, and ileal digesta viscosity of broiler chickens fed with a whole wheat added diet and the diets with different wheat particle sizes. Int. J. Poult. Sci. 2:

66 Table 4-1. Nutrient composition of experimental diets for digestibility ( as is basis) Diet 1 PF 600 µm 900 µm 1200 µm 1500 µm Ingredient (%) Corn Dextrose Cellulose Corn oil Celite Dical P Limestone Vit-TM premix Salt Calculated composition ME (kcal/kg) 3,656 3,274 3,274 3,274 3,274 Crude protein Analyzed nutrients (%) 3 Dry matter Crude protein Ether extract Crude fiber Ash Aspartic Acid Threonine Serine Glutamic Acid Proline Glycine Alanine Cysteine Valine Methionine Isoleucine Leucine Tyrosine Phenylalanine Lysine Histidine Arginine PF = protein-free diet for endogenous amino acid loss determination; 600µm = Diet containing corn with a majority particle size of 600 micrometers; 900µm = Diet containing corn with a majority particle size of 900 micrometers; 1200µm = Diet containing corn with a majority particle size of 1200 micrometers; 1500µm = Diet containing corn with a majority particle size of 1500 micrometers. 2 Supplied per kilogram of diet: vitamin A, 7,937 IU; vitamin D, 2,646 IU; vitamin E, 19.8 IU; riboflavin, 5.3 mg; pantothenic acid, 9.3 mg; niacin, 39.7 mg; choline, 401 mg; vitamin B12, 10.6 µg; biotin, 66.0 µg; Mn, 79.4 mg; Fe, 33.1 mg; I, 1.0 mg; Cu, 5.3 mg; Zn, 66.1 mg; and Se, 180 µg. 3 All diets were analyzed in triplicate by the University of Missouri Agricultural Experimental Station Chemical Laboratories (ESCL) (Columbia, MO). 53

67 Table 4-2. Mean body weight (BW, kg/bird) and body weight gain (BWG, kg/bd) 1,2 Treatment d 28 BW (kg) d 35 BW (kg) d BWG (kg) PF c 0.08 c 600µm ab 0.30 a 900µm ab 0.32 a 1200µm a 0.33 a 1500µm bc 0.21 b SEM P-value < a-c Means within the same column with no common superscript differ significantly (P 0.05). 1 N = 7 cage replicates/treatment where all corn treatments (600, 900, 1200, 1500 µm) birds n = 5, and PF birds n = 8. 2 Birds were fed a commercial corn-soy starter diet from day 0-21 and commercial grower from day 21-28; birds were fed transitional diets from day 29 to 30 and were fed 100% treatment diets from day SEM = Pooled standard error of the means. 54

68 Table 4-3. Mean ileal endogenous amino acid losses (g/100 g DM) collected from the terminal end of the ileum 1,2 Amino acid Current study Burley, 2014 Lemme et al., Aspartic Acid Threonine Serine Glutamic Acid Proline Glycine Alanine Cysteine Valine Methionine Isoleucine Leucine Tyrosine Phenylalanine Lysine Histidine Arginine Total All endogenous loss values were calculated from protein free diet (PF). 2 Analysis was performed in triplicate by the University of Missouri Agricultural Experimental Station Chemical Laboratories (ESCL) (Columbia, MO). 3 Original data from Lemme (2004): Values were converted from mg/kg DM to g/100g DM. 55

69 Table 4-4. Apparent ileal AA digestibility (%) 1 Diet µm 900 µm 1200 µm 1500 µm SEM 3 P-value Aspartic Acid Threonine Serine Glutamic Acid Proline b b b a Glycine b a a a Alanine Cysteine Valine Methionine b a a a Isoleucine b a a a Leucine Tyrosine b ab a a Phenylalanine Lysine b ab a a Histidine Arginine Overall Mean Percentage data analyzed with arcsine transformation. 2 All values are the analyzed means of 3-5 replicates; 600 µm (4), 900 µm (5), 1200 µm (5), 1500 µm (4). 3 SEM = Pooled standard error of the means. 56

70 57 Figure 4-1. Apparent ileal AA digestibility (%, DM basis)

71 Table 4-5. True ileal AA digestibility (%) 1 Diet 600µm 900µm 1200µm 1500µm SEM 2 P-value Aspartic Acid Threonine Serine Glutamic Acid Proline Glycine Alanine Cysteine Valine Methionine Isoleucine Leucine Tyrosine Phenylalanine Lysine Histidine Arginine Overall Mean All values are the analyzed means of 3-5 replicates; 600 µm (4), 900 µm (5), 1200 µm (5), 1500 µm (4). 2 SEM = Pooled standard error of the means. 3 Overall means = mean of true digestibility values for 17 amino acids from each treatment diet. 58

72 59 Figure 4-2. True ileal AA digestibility (%, DM basis)

73 Table 4-6. True AA ileal digestibility (%) from literature EAAL values 1 Diet 600 µm 900 µm 1200 µm 1500 µm SEM 2 P-value Threonine Cysteine Valine Methionine b a a ab Isoleucine Leucine Phenylalanine Lysine Histidine Arginine Overall Mean All values are the analyzed means of 3-5 replicates; 600 µm (4), 900 µm (5), 1200 µm (5), 1500 µm (4). 2 SEM = Pooled standard error of the means. 3 Overall means = mean of true digestibility values for 10 amino acids from each treatment diet. 60

74 61 Figure 4-3. True ileal AA digestibility with literature EAAL values (%, DM basis)