Digestion in Ruminants Wildlife Nutrition PDF

Digestion in the Ruminant ANSC 1011 Introduction Ruminants represent the largest percentage of domestic herbivores. 4-compartment stomach: Allow the animal to use roughage (cellulose) as a source of energy. Microbial population ferment feed. Digestion – Chewing Rumen...

Digestion in the Ruminant ANSC 1011 Introduction Ruminants represent the largest percentage of domestic herbivores. 4-compartment stomach: Allow the animal to use roughage (cellulose) as a source of energy. Microbial population ferment feed. Digestion – Chewing Rumen is filled rapidly. Little or no time to chew. Rumination Animals regurgitate the food eaten earlier and chew it. Process repeats The more the fiber, the more rumination. Reduce particle size of the feed to increase surface area. 1/3 of their life. Digestion – Young Ruminant Rumen is undeveloped in young animals. Reticular groove contracts and forms a tube that bypasses the rumen and reticulum. Keep milk out of the rumen. If the calf drinks milk too quickly: Milk in rumen rots. Severe case of diarrhea Young Ruminant – Esophageal Groove Digestion – Rumen Develops in response to young’s eating solid food. Fermentation as early as 6-8 weeks. All food consumed by ruminants enter the reticulo- rumen. 85-95% is fermented to some degree. Bacteria in the rumen digests carbohydrates (cellulose) and other plant material. Produce VFA, absorbed through the rumen wall. VFA provide 50-70% of the required energy. Digestion – Rumen Rumen wall is covered with papillae. Microbial protein Bacteria can convert nonprotein nitrogen (urea) into bacterial protein. AAs released meet protein requirements. 50% CP and 3% lysine, similar to soybean meal. Energy, vitamin K, water-soluble vitamins. Essential fatty acids. Digestion – Rumen Digestion – Reticulum Lies in front and below rumen; no rumen-reticulum physical division. Site of microbial action (similar to rumen). Pacemaker for rumen contractions. 1 Reticulum Start in reticulum and spread to rumen. 2- 6 Rumen Mix rumen contents – microbial digestion. Move contents through digestive tract. Heavier particles settle, lighter float Digestion – Omasum and Abomasum Omasum Absorbs water, electrolytes, and VFAs Reduces particle size of feed. Abomasum Equivalent to true glandular stomach. Folds in walls provide extra capacity for handling dietary fiber. Digestion – 4 Compartments Forestomachs: Compartments placed anatomically before the glandular stomach. Lining is nonglandular – no mucus or enzymes. Abomasum: Lined with a true mucus membrane. Secretion of gastric juices. From abomasum to rectum – tract is similar to monogastric animals. Eructation Mechanism for removal of gasses produced in microbial fermentation. 600 L/day in a dairy cow. Contractions of the upper sacs of the rumen force the gas toward the esophagus, which dilates, and the gas escapes. Much of the gas goes to the trachea and lungs  muffling effect. The Fermentation Process Rumen microorganisms and ruminant animal live in symbiosis. Dissimilar organisms live together or in close association typically to the advantage of both. How do animal and microbes benefit from this interaction? Microbes digest feeds the animal cannot. Animal provides: warmth, moisture, food supply, waste removal, darkness, pH, and anaerobic environment. Rumination reduces particle size  more available. Contractions keep contents mixed. The Fermentation Process Diverse microbial population Bacteria that digest cellulose, hemicellulose, starch, proteins, sugars, acids. Bacteria that produce ammonia, vitamins, and methane. Nearly 40 species of ciliate protozoa. Help prevent bacterial overgrowth. Virtually everything the ruminant consumes is affected by fermentation. Some feeds changed tremendously. The Fermentation Products VFAs are a major product of ruminal fermentation. Acetate, propionate, butyrate, isobutyrate, valerate, isovalerate. VFAs provide 50-70% of total energy needs. Acetate: precursor for milk fat. Propionate: main source of glucose  brain function and milk production. Butyrate: energy source for rumen epithelium  nutrient absorption. The Fermentation Products Much protein is broken down to ammonia and organic acids. Microorganisms use ammonia to synthesize AAs for their own use. NPN sources can also be used by microorganisms. Important in diet formulation as means of reducing cost. Heat is also a major product of fermentation – winter. The Fermentation Products Most of plant sources are low in lipids. Lipids found in feeds are not changed much by fermentation. High levels of fat are bad for microbes and reduce their abilities. Advantages of the Ruminant System Microbial fermentation has the potential to digest feedstuffs that the animal’s enzymatic digestion process cannot. Increases the value of feeds such as prairie hay, corncobs, wheat straw. Ruminants have the ability to convert low-quality feed into high-quality food products. Microbes synthesize essential nutrients not found in feeds such as vitamins, AAs, and fatty acids. Would be excreted if fermentation occurred in the cecum. Disadvantages of the Ruminant System Microbial fermentation potentially decrease the overall quality of the ruminant diet by destroying essential nutrients found in the feed. Fermentation requires and wastes large amounts of energy. A significant portion of dietary energy is lost as heat and gaseous products. Greater susceptibility to digestive upsets (bloat, acidosis). Nutrition of Wildlife Species Introduction Wild species do not require supplementation in their natural habitat. Many factors affect the environment in which wild animals live. Climate change Habitat loss Decline of biodiversity Pollution Habitat alterations Invasive species Human disturbances Introduction Why is it important to understand wild animal species eating habits? Conservation of species: nutrition ensures reproduction. In situ conservation Ex situ conservation Recreation (safaris, zoos) Game farms Developing Diets of Wild Species Dietary habits in the wild. Gastrointestinal morphology and physiology. Needs of similar domestic species whose requirements are known. Nutritional research on exotic species in the wild and in captivity. Environmental features that affect energy and nutrient need. Dietary Habits in the Wild Wild species adapt their diets according to their environment. Bulk and roughage grazers: large grazing animals (large stomachs) Relatively low-quality feeds, mainly grass. Browsers: selectors of juice, concentrated herbage (small stomachs) Leaves, flowers and fruits, shrubs, and tress. Dietary Habits in the Wild Intermediate feeders: herbivores that eat both grass and leaves Ability to adapt in different seasons to grass and leaves. Ability to tolerate variation in quality of the diet. GI Tract Morphology and Physiology Digestive tract morphology has a high correlation with natural diet. Presence of a ruminoreticulum  qualitative nutrients requirements similar to those of cattle. Large intestine has a cecum (capacity of microbial fermentation  nutrient needs could be similar to those of the horse. A simple stomach with limited gut capacity  similar to a pig. GI Tract Morphology and Physiology Extrapolation of nutrient requirements from domestic species is not always useful. Goal of livestock producers is to maximize yields (growth, milk, eggs). Different goals for wildlife species (conservation). Recommended that wild/exotic animals should be fed a maintenance diet. Nutritional guidelines developed from research in captive animals. Must be used carefully. Mostly anecdotal, not scientific. Supplementation (In situ Conservation) Focuses on supplying animals with the necessary nutrients that forage available cannot supply. Nutrients that can be limited to wild animal species: Energy Protein Minerals