Animal Nutrition

1. Animal Nutrition

2. Nutrition: food taken in, food taken apart, food taken up

3. Nutrition is essential for • Energy production (ATP): all activities from molecular to cellular level • Biosynthesis: supply raw materials to build complex molecules to grow, maintain & reproduce

4. Animals have diverse diets: • herbivores

5. carnivores

6. omnivores

7. Most animals are opportunistic feeders

8. Essential nutrients: materials that an animal’s cells require but cannot synthesize. • 4 classes of essential nutrients: • essential amino acids • essential fatty acids • vitamins • minerals

9. Amino acids: Organic molecule with an amino group and an acid group

10. Essential amino acids: • Must be obtained from prefabricated food • 8 in humans (infants - 9 – histidine) Animal products (meat, cheese, eggs) are complete “proteins”.

11. Essential amino acids for adults • Most plants have “incomplete proteins” Beans and other legumes Methionine Valine Threonine Phenylalanine Leucine Corn (maize) and other grains Isoleucine Tryptophan Lysine

12. Temporary use of muscle protein as a source of amino acids (penguins).

13. Essential fatty acids: • Long carbon chain with an acid group • Unsaturated fatty acids (linoleic acid to make membrane phospholipids) • Seeds, grains vegetables SaturatedFatty acid Unsaturated Fatty acid

14. Vitamins: • Organic molecules with diverse functions; required in the diet in small amounts. • Water soluble: B-complex, C, Biotin • Fat soluble: A, D, E, K

18. Minerals: • Inorganic nutrients required in small amounts

20. Dietary deficiencies: • Undernourishment: diet that supplies insufficient chemical energy • Malnourishment: long term absence from diet of one or more essential nutrients

21. Undernourishment: diet that supplies insufficient chemical energy • Body uses up stored fats and carbohydrates • Breaks down muscles • Brain will become protein deficient • Death or irreversible damage • Places with turmoil in society (war, drought), or eating disorders

22. Malnourishment: long term absence from diet of one or more essential nutrients • Among herbivores (fragile bones from lack of phosphorus) • Carnivores switch prey • Disease, deformities, death in humans, especially children

24. Four main feeding mechanisms in animals: • Suspension feeders • Substrate feeders • Fluid feeders • Bulk feeders

25. Suspension feeders: clams, oysters, whales

26. Substrate feeders: live in or on the food source, caterpillars Feces Caterpillar

27. Fluid feeders: suck nutrient-rich fluid from living host (have specialized organs) • Bulk feeders: Eat large pieces of food.

28. Four main stages of nutrition: • Ingestion: act of eating • Digestion: food is broken down into small molecules that can be absorbed; mechanical & chemical – enzymatic hydrolysis) • Absorption: animal cells take up the break-down products • Elimination: passing out undigested material

29. LE 41-12 Small molecules Pieces of food Chemical digestion (enzymatic hydrolysis) Nutrient molecules enter body cells Mechanical digestion Undigested material Food INGESTION ELIMINATION DIGESTION ABSORPTION

30. Intracellular digestion: food is broken down inside food vacuoles

31. Extracellular digestion: Breakdown happens in compartments that are outside of the body; hydra, earthworm, grasshopper, birds, humans

32. Mouth Tentacles Gastrovascular cavity Food Epidermis Mesoglea Gastrodermis Nutritive muscular cells Flagella Gland cells Food vacuoles Mesoglea

33. Crop Gizzard Intestine Esophagus Pharynx Anus Mouth Typhlosole Lumen of intestine Earthworm

34. Midgut Hindgut Foregut Esophagus Rectum Anus Crop Mouth Gastric ceca Grasshopper

35. Esophagus Stomach Gizzard Intestine Mouth Crop Anus Bird

36. Salivary glands Mouth Esophagus • Human digestive system Gall- bladder Stomach Small intestines Liver Pancreas Large intestines Rectum Anus A schematic diagram of the human digestive system

37. Peristalsis: alternating waves of contraction and relaxation in the smooth muscles lining the alimentary canal.

38. Oral cavity: • Mechanical digestion, chewing. • Chemical digestion: Saliva

39. Protein digestion Nucleic acid digestion Fat digestion Carbohydrate digestion Oral cavity, pharynx, esophagus Polysaccharides Disaccharides Salivary amylase Smaller polysac- charides, maltose

40. Functions of saliva • salivary amylase, hydrolyzes starch • lubrication: mucin (glycoprotein) • preparation of food bolus • buffer • antibacterial function

41. Swallowing has to be carefully choreographed to prevent food from entering airway

44. Stomach: • stores food • continues digestion by churning and mixing with gastric juices (chyme). • low pH (~2)kills bacteria, HCl secreted by parietal cells • digests protein – pepsin, chief cells produce pepsinogen which is activated by HCl.

45. Esophagus Cardiac orifice Stomach Pyloric sphincter 5 µm Small intestine Folds of epithelial tissue Interior surface of stomach Epithelium Pepsinogen and HCl are secreted into the lumen of the stomach. Pepsinogen Pepsin (active enzyme) Gastric gland HCl HCl converts pepsinogen to pepsin. Pepsin then activates more pepsinogen, starting a chain reaction. Pepsin begins the chemical digestion of proteins. Mucus cells Chief cells Parietal cells Chief cell Parietal cell

46. Stomach secretes thick mucus to prevent its cells from getting corroded by HCl. • Sphincter (ring-like valve) at the junction of stomach and esophagus prevents backflow. Backflow causes “heartburn”. • Sphincter between stomach and small intestine allows food to go out in squirts. • Takes 2 to 6 hrs after a meal for the stomach to empty.

47. Figure 22.10

48. Protein digestion Nucleic acid digestion Fat digestion Carbohydrate digestion Oral cavity, pharynx, esophagus Polysaccharides Disaccharides Salivary amylase Smaller polysac- charides, maltose Stomach Proteins Pepsin Small polypeptides

49. Bacteria Mucus layer of stomach 1 µm