Animal Nutrition Requirements and Utilization

Nutritional Requirements heterotrophs require nutrition to supply –energy sources –fats kcal/g –carbohydrates kcal/g –proteins kcal/g storage molecules basal metabolic rate – kcal/day

use of energy stores during starvation Figure 50.3

Nutritional Requirements heterotrophs require nutrition to supply –carbon skeletons acetyl groups - from fats, carbohydrates, or proteins essential amino acids - from proteins essential fatty acids - from fats/oils

acetyl group is an essential dietary requirement Figure 50.4

essential amino acids from plant products Figure 50.5

Nutritional Requirements heterotrophs require nutrition to supply –metabolic & structural factors mineral nutrients - various sources vitamins (coenzymes, etc.) - various sources

mineral elements and vitamins Tables 50.1, 50.2

Feeding Adaptations heterotrophs have adaptations suited to their food sources –mammalian teeth share common structure differ in shape, distribution, and use

exposed enamel, bony dentine, sensitive pulp cavity Figure 50.7

the type and arrangement of teeth reflect an animal’s diet Figure 50.7

Digestive Anatomy tubular gut –extends from mouth to anus –creates an enclosed extra-cellular chamber –includes sequential functional segments mouth & buccal cavity (or gizzard) –intake & fragmentation of food stomach (or crop) –storage of large meals – +/- digestion

Digestive Anatomy tubular gut –(small) intestine enzymatic digestion absorption of biomolecule subunits –hindgut (large intestine) reabsorption of water & ions storage of undigested materials –rectum expulsion of feces from anus

tubular digestive systems Figure 50.8

increased intestinal surface area Figure 50.9

length, folds, villi, microvilli Figure 50.9

Digestive Anatomy intestinal adaptations –symbiotic bacteria or protists –modifications to increase surface area –secretion of hydrolytic digestive enzymes zymogens activated in intestine biomolecules digested to monomers

human digestive system Figure 50.10

Digestive Anatomy human digestive system –structure of the tube lumen, surrounded by mucosa –secretes mucus, enzymes, HCl –absorbs nutrients

Digestive Anatomy human digestive system –structure of the tube submucosa –blood & lymph vessels –sensory/regulatory nerve network two muscle layers –circular muscle layer –longitudinal muscle layer –nerve network

Digestive Anatomy human digestive system –structure of the tube serosa - outer jacket layer peritoneum - surrounding membrane

layers of the tubular gut Figure 50.11

Function of the Gut human digestive system –food moves through the gut by peristalsis propulsive wave of smooth muscle contraction control points employ sphincter muscles

Function of the Gut human digestive system –digestion begins in the mouth chewing & salivary secretions initiate food breakdown swallowing maneuvers food –through the pharynx –over the epiglottis –into the esophagus peristalsis delivers food to the stomach

swallowing is a series of reflex actions Figure 50.12

peristaltic transport Figure 50.12

Function of the Gut human digestive system –digestion continues in the stomach gastric mucosa secretes digestive substances –mucus - protects mucosa –HCl - maintains pH ~2 –pepsinogen »endopeptidase »activated by low pH & autocatalysis

stomach secretions Figure 50.13

activation of pepsinogen Figure 50.14

Function of the Gut human digestive system –digestion continues in the stomach chyme –product of digestion & mixing –propelled into the small intestine through the pyloric sphincter

Function of the Gut human digestive system –digestion & absorption in small intestine duodenum –receives chyme –receives bile »produced in the liver »stored in the gall bladder »delivered through common bile duct »emulsifies fats into micelles

bile production, storage and delivery to the small intestine Figure 50.15

Sources & functions of digestive enzymes Table 50.3

Function of the Gut human digestive system –digestion & absorption in small intestine duodenum –digests molecules »peptides => amino acids »disaccharides => monosaccharides »fats => monoglycerides, fatty acids

Function of the Gut human digestive system –digestion & absorption in small intestine jejunum & ileum –absorb monomeric subunits »ions & nutrients enter by > active transport > co-transport > facilitated diffusion

Function of the Gut human digestive system –digestion & absorption of fats monoglycerides & fatty acids –enter microvilli –re-assembled –combined with cholesterol & phospholipids into chylomicrons –delivered to blood in lymph

absorption of the products of lipid digestion Figure 50.16

Function of the Gut human digestive system –water and ion absorption in the colon peristalsis moves the remains to the colon water & ions are removed from the slurry vitamin K & biotin are produced by E. coli

Regulation of Gut Activities autonomic reflexes coordinate activities in different parts of digestive tract –e.g. salivation, swallowing, etc. hormonal signals control digestive activities –e.g. pancreatic secretion, bile release, etc.

hormonal control of digestion Figure 50.18

Regulation of Fuel Metabolism absorptive period supplies nutrients to the body –glucose stored as glycogen or fat –monoglycerides & fatty acids stored as fat –amino acids stored as blood plasma proteins or converted to glucose (gluconeogenesis)

hormonal control of blood glucose Figure 50.19

fuel transport and metabolism during absorptive period Figure 50.20

Regulation of Fuel Metabolism post-absorptive period utilizes stored nutrients –fuel molecules return to blood when needed

fuel transport and metabolism in post- absorptive period Figure 50.20