1 Review of Nutrients and Digestion Focus on the Comparative Aspects of Nutrient Digestion Absorption and Utilization Between Ruminants Nonruminants and Hind gut Fermenters Learning Objectives for Comparative Animal Nutrition II I Understand comparative nutrition of 1 Ruminants 2 Non ruminants and 3 Hindgut fermenters Learn chemical components of 1 Fiber carbohydrates 2 Starch carbohydrates 3 Protein and 4 Lipid III Learn key sites of gastrointestinal tracts GIT IV Know for each of 4 nutrients and each of 3 species Primary site of digestion stomach small or large intestine Principal method of digestion fermentative vs enzymatic End products of digestion e g amino acids glucose Primary site for absorption of end products of digestion stomach small or large intestine Example essay question s on comparative animal nutrition What are the key differences and similarities between how fiber CHO starch CHO protein or lipid is digested in horses or pigs compared to cattle 1 2 3 2 What are the key differences and similarities between how protein is digested in horses compared to cattle o In cattle there is extensive fermentative digestion of protein to amino acids AA in the stomach Rumen degradable protein RDP with AA thereafter being deaminated by microbes to NH3 and carbon skeletons o Microbes use carbohydrates carbon skeletons and NH3 to synthesize microbial protein MP rich in essential AA digestion to AA o The MP and rumen undegradable protein RUP go to the small intestine SI for enzymatic o From the SI the AA are actively absorbed into the blood stream There is limited fermentative digestion of protein in large intestine LI of cattle o In horses there is limited protein digestion in the stomach but extensive enzymatic digestion e g trypsin of dietary protein with AA absorbed from the SI like in cattle o In the LI there is extensive protein fermentation like in the stomach of cattle However there is no enzymatic digestion of protein in LI and AA can not be absorbed from LI o Thus MP protein produced in the LI of horses can NOT be used to meet essential AA requirements 4 Key definitions I II Feed a material which after ingestion by an animal is capable of being digested absorbed and utilized Nutrient a component of a feed that aids in the support of life a Water b Dry matter Inorganic matter minerals Organic matter Carbohydrate Lipids Proteins Vitamins Composition of feedstuffs wet basis Item Corn plant Dried Alfalfa Water 66 5 10 0 Carbo hydrate 28 5 85 1 65 0 72 2 71 2 81 8 Fat 1 0 2 0 1 9 Protein Ash 2 5 18 0 12 2 1 5 5 0 1 7 Wheat grain Values in expressed on a dry matter basis 13 0 5 6 3 Composition of animal products on wet basis Item Dairy cow Muscle Pigs 8 kg BW 30 kg BW 100 kg BW Water 57 0 72 0 73 0 59 0 49 Carbo hydrate 2 0 0 6 1 0 1 0 1 0 Fat 20 6 0 3 6 0 24 0 36 0 Protein 17 2 21 4 17 0 13 0 12 0 Ash 5 0 1 5 3 0 3 0 2 5 Comparative nutrition Nonruminant vs hind gut fermenter vs ruminant animals Nutrient Fiber CHO Pig Limited fermentation in LI VFA Horse Cow Fermentative in LI VFA Fermentative in rumen VFA Enzymatic in SI Glc Some Enzymatic in SI Glc Some fermentative in LI fermentative in LI Fermentative in rumen VFA Some enzymatic in SI Starch CHO Protein VFA AA VFA AA Enzymatic in SI Enzymatic in SI Glc Fermentative in rumen MP Enzymatic in SI AA Fermentative in rumen Some enzymatic in SI LCFA Lipid Enzymatic in SI Enzymatic in SI LCFA LCFA Digestive Systems Nonruminant GIT 29 7 29 35 7 8 9 4 Digestive Systems Ruminant GIT 9 3 68 20 10 Ruminant animal GIT anatomy Stomach The ruminant stomach comprised of 4 compartments i Reticulum ii Rumen iii Omasum and iv Abomasum The reticulum rumen omasum are lined with non glandular mucous membrane Absorption but no secretions Abomasum is lined with glandular mucosa Secretion of enzymes Left side Right side Ruminant animal GIT anatomy Reticulum The reticulum comprises approximately 5 of the ruminant stomach capacity Pouch like compartment located in the cranial part of the stomach The epithelial lining forms polygonal cells that give it a honey combed appearance Dense feed or foreign objects tend to settle in the reticulum Hardware disease Entry of the esophagus into the reticulo rumen reticulum on the left Rumen on the right 11 12 5 Ruminant animal GIT anatomy Rumen The rumen comprises approximately 80 of the ruminant stomach capacity Principle site of microbial fermentation Papillae are tongue shaped projections that line the rumen to greatly increase its surface area for absorption of volatile fatty acids VFA Short chain VFAs passively diffuse across the epithelium which then get transported via ruminal veins to the hepatic portal vein for transport to the liver 13 14 Ingestion and rumination in ruminant animals Rumination Maximal dimensions of feed particles to pass from rumen to the omasum is 1 mm Only 10 to 15 of feed is reduced in 1 mm during the ingestion of feed Thus most of the particle size reduction occurs during rumination which includes o Regurgitation o Reinsalivation o Remastication o Reswallowing Time observed min Ruminating 94 133 Feed Oat straw Med quality hay Good quality hay Eating 41 58 20 40 27 31 Corn silage 31 58 High grain diet 4 10 63 87 55 74 60 83 5 25 Microbial fermentation in the reticulo rumen Anaerobic microbes Produce VFAs from carbohydrates that supply 60 to 70 of the ruminant animal s energy requirement Ferment protein and can utilize non protein nitrogen sources e g urea to generate lots of microbial protein that contains high concentrations of essential amino acids Produce vitamin K and b complex vitamins that meet most of the ruminant animals requirements Source Progressive Farmer 15 6 Ruminant animal GIT anatomy Omasum The omasum comprises approximately 8 of the ruminant stomach capacity Contains leaves of tissue like pages of a book that greatly increases its absorptive capacity Acts as a sieve to prevent larger particle from flowing to the abomasum About 30 to 60 of water entering the omasum is absorbed VFAs sodium and potassium also absorbed from the omasum Ruminant animal GIT anatomy Abomasum The abomasum comprises approximately 7 of the ruminant stomach capacity Pear shaped compartment of the stomach that is relatively wide next to the omasum that narrows as it junctions with the small intestine Similar to the stomach of non ruminant animals the abomasum contains glandular mucosa and HCl producing parietal cells The glandular mucosa also secrets lysozyme an enzyme that breaks down