IAD 202. Livestock Production & Development Wolfgang Pittroff Lecture 2

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1 IAD 202 Livestock Production & Development Wolfgang Pittroff Lecture 2

2 Introduction into Animal Nutrition Ruminants: functional anatomy, digestive strategies, comparative anatomy Monogastrics: functional anatomy, principles of nutrient absorption

3 Ruminants Major anatomical feature: multicompartment stomach First compartment: Reticulum Second compartment: Rumen Third compartment: Omasum Fourth compartment: Abomasum

4 Ruminants Reticulum: grind, transport, absorb, trap heavy objects Rumen: mix, absorb Omasum: extract water, transport, absorb Abomasum: digestion, secretion of acids, enzymes

5 Stomach System of the Ruminant

7 Layers in the rumen

9 Rumen

10 Ruminants Basic Nutrition: Resident microbes aid in digestion attack all feed ingredients Energy substrates produced: VFA s VFA s = products of fermentation (principal substrate carbohydrates) Feed protein broken down to amino acids and NH 3 From amino acids and NH 3 : microbial protein

11 Ruminants Sometimes the result of microbial digestion is the production of toxic substances for example, the amino acid mimosine, present in Leucaena leucocephala, is degraded in the rumen into a goitrogenic metabolite (what is this??) Some Brassica species contain glucosinolates that are also degraded into goitrogenic, toxic substances

12 Ruminants Basic Nutrition Ruminants absorb most of their energy in form of volatile fatty acids: Acetic acid (A) => liver, milk fat Propionic acid (P) => liver, oxidation, glucose Butyric acid (B) => epithelium, energy for muscle, fat The molar (mass) ratios are: 65:25:10 on roughage (A P B) 50:40:10 on concentrate diets (A P B) (1 mol is the mass of a substance in g of its molecular weight)

13 Ruminants & Protein Microbial digestion/fermentation of plant material renders volatile fatty acids as energy substrates Process is anaerobic therefore energetically inefficient Microbes digest feed protein Principal source of N of the ruminant is microbial protein

14 Ruminants & Protein Because ruminants can derive all their protein (for modest performance levels) from the digestion of microbes, they can be maintained on a diet that contains only non-protein sources of nitrogen urea for example

15 Important Feeding Considerations There may be properties of local breeds that specifically facilitate adaptation to particularly poor feeds However, it is not fully understood if such breed differences are caused by differences in metabolic requirements or other adaptation mechanisms However, there are localized strains of ruminal microbes specifically adapted to properties of local forages (both in terms of digestion and detoxification capacity)

16 Ruminants Basic nutrition: Ruminants need glucose like all animals, but they get very little from their normal feeds A major energy source from the rumen, the VFA propionic acid (propionate) serves as the most important precursor for glucose Result: the production of glucose in the ruminant (gluconeogenesis) is highest after feeding

17 Ruminants: Absorption of nutrients The rumen lining (mucosa/epithelium) is densely covered by papillae (worm-like protrusions) Papillae are responsible for the absorption of VFA s and NH3 VFA s create an acid environment therefore, the rumen contents must be buffered (saliva) The rumen is highly mobile and motile this is managed by a very complex system of nerves and muscles

18 Papillae cross section

19 Dynamic change of papillae in an impala antilope with increasingly better nutrition (clockwise from the top)

20 Ruminants: Omasum Pumps digesta downward Absorbs nutrients through an absorptive epithelium with papillae (in the rumen, only the papillae absorb) Extracts water Strong muscles support the leaves Large ruminants have more leaves

21 Ruminants: Abomasum Corresponds to the simple stomach of the monogastric Species difference between ruminants in terms of HCl production capacity Produces lysozyme, a bactericidal enzyme that breaks down bacterial cell wall (only mammal to produce this enzyme in the digestive system)

22 Rumen Development The rumen develops over time The newborn ruminant functions like a monogastric (milk digestion) Reticular groove facilitates passing of milk into the abomasum without entering the rumen The reticular groove is formed by muscles and folds and functions like a tube reaching from the oesophagus directly into the abomasum Its closure is caused by the suckling reflex

23 Rumen development in cattle

24 Digestive Strategies in Ruminants (they are not all the same or does a giraffe look like a sheep to you?)

25 Note:

26 Digestive Strategies All livestock species fall in the categories of IM and GR feeders (intermediate and grass-roughage feeders) Important IM species are goats, camels Important GR feeders are cattle and sheep

27 Digestive Strategies The principle is the same: Eat fibrous material Have microbes digest the fiber Absorb energy substrates from the microbial digestion (volatile fatty acids, VFA s) Digest the microbes for protein and vitamins

28 Digestive Strategies Major difference is in the amount of soluble, rapidly fermentable material that is consumed concentrate selectors prefer concentrated, soluble nutrients (for example certain leaves, fruit), and roughage feeders prefer bulky material with much less soluble material

35 Digestive Strategies in Ruminants Saliva production of cattle eating roughage can exceed 180 l per day Saliva is important as a buffer and for transport and moistening of feed The ruminant can recycle excess NH 3 by absorbing it, converting it into urea and then shuttle it back through blood and salivary glands (saliva) into the rumen

36 African Deer a: reticulum; c: cranial pillar; f: caudodorsal blindsac; h: caudoventral blindsac

37 Important Feeding Considerations Ruminants can be killed by supplying feedstuffs that cause severe disturbances in their forestomach system Dangerous are all feedstuffs that cause rapid fermentation processes, or that impede digesta turnover and ruminating (e.g., young clover, alfalfa) Low forage quality does not mean that animals are limited by intake capacity

38 Important Feeding Considerations Ruminants evolved to survive well on low quality forage Adaptation to low quality forages is their greatest problem in high-intensity production systems The economics of intensification concepts are usually worthless because not all aspects of system performance are accounted for

39 Mixed Species Grazing Knowing the specific differences between feeding types enables you to: Select the right feed stuffs for your animals Use animals for vegetation management Optimize the use of resources by maximizing utilization of natural pastures

40 Dietary Overlap What does variable dietary overlap between herbivore, ruminant species mean? The understanding of this overlap is critical for optimum use of forage resources The understanding of this overlap is critical for resource-protecting grazing management Dietary overlap is seasonally dynamic

41 Dietary Overlap in Ruminants Deer Diet in Hopland 100% 80% 60% 40% Browse Forbs Grass 20% 0% Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

42 Dietary Overlap in Ruminants Sheep Diet in Hopland 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Browse Forbs Grass

45 Sheep and Goats in Central Asia Mixed Species Grazing

47 Ruminant Nutrition Health Problems Milk fever: Ca deficiency associated with parturition and onset of lactation More common in dairy than in beef cows Exact causes still not well understood Symptoms: staggering, subnormal T, cold ears, no defecation, inability to get up, lying on the sternum Treatment: highly available Ca Prevention: feeding program for optimum Ca and P

48 Ruminant Nutrition Health Problems Ketosis: This is a metabolic disorder where the level of ketone bodies (products of fatty acid oxidation) is elevated (acetone smell of breath and urine) Occurs always early in lactation, or in late pregnancy in sheep Inappetence most important symptom not very specific!

49 Ruminant Nutrition Health Problems Ketosis: blood glucose levels very low, ketone bodies high The disorder arises from the need of the ruminant metabolism to shift emphasis in ATP generation towards oxidation of longchain fatty acids this is the destination of the burning of fat

50 Lactation Mammary gland: originates as a sudoriferous gland Protect the neonate from infectious diseases Nourish the growing animal Do you know of any animal species that uses milk as long as humans? Given that, do you think milk is the perfect food for all ages?

51 Anatomy Number of mammary glands varies with species Cow: 4 glands, 4 teats Sheep and goats: 2 glands, 2 teats (except the Boer goat!) Mare: 4 glands, two teats Sow: 6-20 glands, each with a teat Note: the following anatomy discussion focuses on the cow!

53 Anatomy The basic unit of the exocrine mammary gland is the alveolus. Each alveolus has its own independent blood supply An alveolus is a single layer of epithelial cells forming a sac. The epithelial cells are surrounded by myoepithelial cells (contractile cells) Blood supply to the mammary gland is of paramount importance in the cow, synthesis of one gallon of milk requires 500 gallons of blood flow

54 Anatomy All substrates and precursors for milk components must pass into the epithelial cells. There, synthesis processes take place, and milk is secreted into the lumen of the alveolus Some components (immunoglobulins, e.g.) pass intact Alveoli are organized in lobules (~200 per lobule) Lobules are organized in lobes

55 An alveolus note connective tissue in stroma (space between alveoli)

56 Alveolus: Note: myoepithelial cells

58 Section through a quarter of a cow udder previous slide enlarged view of cutout area

59 Anatomy Milk collects inside the alveolus At milk letdown, milk leaves the alveolus and flows to the gland cistern From the gland cistern the milk is forced through the annular ring into the teat cistern (either by suckling or milking) and then out through the streak canal The streak canal is surrounded by a sphincter muscle can be too tight or too weak

60 Physiological Processes Mammogenesis Mammary gland development Lactogenesis Induction of lactation Galactopoiesis Maintenance of lactation

61 Mammogenesis Mammary gland development accelerates as the female reaches puberty Development is under the influence of estrogen and progesterone (ovarian hormones) Estrogen is primarily responsible for duct and and cistern growth, whereas progesterone stimulates growth of the alveoli

62 Lactogenesis More than 90% of milk proteins are milkspecific, i.e. are synthesized only in the alveolar cells Casein is the most important fraction (~80%) Both energy and protein deficiency of the cow can cause a reduction milk protein concentration

63 Lactogenesis Milk fat is synthesized in the alveolar cells, using both long-chain fatty acid precursors, and short- and medium chain FA synthesized in the alveolar cells Short chain FA come from the blood most important are acetate and butyrate The FA pattern of milk reflects nutrition

64 Lactogenesis Lactose is also synthesized in the mammary gland, using glucose from blood as its most important precursor Not really susceptible to changes in feeding Milk also contains many minerals and vitamins extracted from blood. B-vitamins in milk are produced by rumen microbes

65 Lactogenesis The perhaps most important hormone is prolactin, under whose influence the alveolar epithelial cells secrete the milk solids protein, lactose and fat into the lumen

66 Milk Let-Down Milking or nursing will only empty the cisterns and large ducts of the udder For the milk to leave the alveoli, muscular action is required This is stimulated by oxytocin, a brain hormone

67 Advanced milking systems for cattle that need the calf present for milking (Nicaragua)

68 Mastitis Infectious agents are usually bacteria, but also myocplasma, fungi and algae Mechanical and thermal trauma, or chemical insult predispose the mammary gland to mastitis Mechanical milking devices must be designed to minimize the predisposing risk

69 Abnormal milk

70 Worldwide problem mastitis treatment in Afghanistan

72 Monogastrics Over the last 50 years, drastic changes in genetics and feeding management of pigs in industrialized nations occurred Domestic pigs evolved from scavengers/grazers to consumers of food fit for human consumption In many developing countries, pigs are still kept in extensive systems, but some countries have embarked on industrialization of pork production

73 Pigs having a great time in Spain

74 Pig having a great time in U.S.

75 This is also a pig

76 Pigs in Nigeria high-tech system

78 Porcine Stomach Cardiac gland region (mucous) Fundus gland region (HCl) Pylorus gland region (mucous)

79 Stomach Regions

80 Non-ruminant stomach Reservoir Mechanical reduction of food Hydrolysis preparation and initiation of protein and fat digestion Absorption Protection (emesis vomiting)

81 Non-ruminant stomach Cardia (sphincter) Fundus Body Pylorus (sphincter)

82 Non-ruminant stomach Highly distensible organ with valves on both ends very muscular capacity up to 8 liters (in pigs) Highly vascularized Specialized secretory mucous lining Two types of secretory glands: mucous secretion (autoprotection; can also produce alkaline mucous (Brunner s glands)) acid secretion (anti-microbial; hydrolysis)

83 Non-ruminant stomach Three populations of glands: Cardiac glands (diffuse geography, not cardia) produce mucus Fundic glands (occupy more area than the fundus) produce HCl and enzymes Pyloric glands produce mucus

84 Small Intestine Comprises three segments: Duodenum Jejunum Ileum Protein digestion and absorption Fat digestion and absorption (enzymes and emulsifiers from pancreas)

85 Small Intestine Is a thin organ with an incredibly large internal surface (human: 200 m 2 ) Folds and microvilli multiply surface area by about 600 times Most nutrients enter the body through these villi They either permeate or are moved by transporter molecules (glucose, e.g.)

86 Cross section of the duodenum with parts of the pancreas

87 Cross section of the jejunum

88 Black: villi Red: submucosa Yellow: extensions of the submucosa Green: muscularis

89 Absorption of Nutrients Most nutrients are absorbed in the small intestine (exception ruminants) Most carbohydrates, amino acids (digestion products of proteins), glycerol and fatty acids require active transport systems These are energy intensive energy requirements of the small intestine are a major factor in overall energy maintenance demand

91 Liver The liver is the main metabolic organ About 75% of the blood flowing into the liver comes from the portal vein system i.e., digestion products are delivered to the liver for further processing

92 Biliary System Gall Bladder Bile is a secretion product of liver cells (hepatocytes) Bile contains mostly bile acids important compounds in the digestion of fat Some species store bile in the gall bladder, and empty this bladder regularly into the duodenum

93 X X X

94 Pancreas The pancreas is an organ that is both exocrine and endocrine The exocrine part (acini) secretes important enzymes that aid digestion in the duodenum Proteases, lipases and amylase are secreted

95 Pancreas The endocrine part of the pancreas (Islets of Langerhans) produces key hormones in the regulation of energy and carbohydrate metabolism insulin, glucagon and somatostatin

96 Pancreas in relation to stomach and duodenum

97 Summary Ruminants and monogastrics differ primarily in (a) the type of feed they consume, (b) the presence or absence of a forestomach system, and (c) the type of energy and protein substrate they naturally depend on

98 Summary Ruminants can live on substrates no other mammals can metabolize due to the presence of symbiotic microbes They absorb the vast majority of their energy intake in the rumen and omasum Protein (mostly of microbial origin) digestion takes place in the abomasum, and protein substrates (as well all other feed components) are absorbed in the small intestine

99 Summary Many metabolic disorders originate in feeding systems that do not match evolutionary predisposed requirements Whenever one develops feeding systems for ruminants, care must be taken to ensure that both microbes and the host are fed

100 Summary Ruminants differ considerably in the feeding strategies good knowledge of dietary overlap between different species allows optimum use of resources

AF 1201 Digestive System. Dr. A.M.J.B. Adikari Dept. of Animal and Food Sciences

AF 1201 Digestive System. Dr. A.M.J.B. Adikari Dept. of Animal and Food Sciences AF 1201 Digestive System Dr. A.M.J.B. Adikari Dept. of Animal and Food Sciences Complex / Compound Stomach Large structure, located on the left side 4 parts Rumen, Reticulum, Omasum Abomasum Fore stomach