ANIMAL NUTRITION Chapter 41

1. ANIMAL NUTRITIONChapter 41 Animals are heterotrophs Nutrition is not only the need for food, but also the need for specific food components.

2. Require food for • fuel (chemical energy) • carbon for its own molecules • essential nutrients FUEL - ATP BIOSYNTHESIS ENERGY STORAGE

3. Food Processing Ingestion Digestion Absorption Elimination Act of eating Process of breaking food down into molecules small enough for the body to absorb Take up small molecules from the digestive compartment Undigested material passes out of the digestive compartment Intracellular Extracellular

4. Dietary Categories (represents the kind of food the animal usually eats) Herbivores Carnivores Omnivores Consume animals as well as plants or algae Mainly eat plants and algae Eat other animals Gorillas Cows Hares Snails Sharks Hawks Spiders Snakes Cockroaches Crows Bears Raccoons Humans

5. Most animals are opportunistic – Eating foods that are outside their main dietary category

6. Feeding Mechanisms Suspension (filter) feeders Substate feeders Fluid feeders Bulk feeders Sift small food particles from the water Live in or on their food source Suck nutrient rich fluids from a living host Eat relatively large pieces of food Clams Oysters Baleen whales Maggots Earthworms Mosguitos Leeches Hummingbirds Bees Most animals

7. Feeding Mechanisms Suspension (filter) feeders Sift small food particles from the water Sponges Clams Oysters Baleen whales

8. Feeding Mechanisms Substate feeders Live in or on their food source Maggots Earthworms

9. Feeding Mechanisms Fluid feeders Suck nutrient rich fluids from a living host Mosguitos Leeches Hummingbirds Bees

10. Feeding Mechanisms Bulk feeders Eat relatively large pieces of food Most animals

11. Food Processing Ingestion Digestion Absorption Elimination Act of eating Process of breaking food down into molecules small enough for the body to absorb Take up small molecules from the digestive compartment Undigested material passes out of the digestive compartment Intracellular Extracellular

12. Virtually all food, whether of plant or animal origin, consists of highly complex compounds that cannot be used without first being broken down to simpler compounds = digestion. CHOs, fats and proteins can all be used as fuel. Campbell; Fig. 9.19

13. Net Energy Value of Foods 4 kcal per gram for protein 4 kcal per gram for CHO 9 kcal per gram for lipid Amino acids Simple sugars Fatty acids Campbell; Fig.40.10

14. If the food intake exceeds the energy used, most animals store the surplus as fat, irrespective of the nature of the food.

15. Net Energy Value of Foods 4 kcal per gram for CHO  Fast  Aerobic or anaerobic  Storing glycogen also requires storing water 9 kcal per gram for lipid  Slower  Aerobic Simple sugars Fatty acids Campbell; Fig.40.10

16. When blood glucose level rises, a gland called the pancreas secretes insulin, a hormone, into the blood. 1 Insulin enhances the transport of glucose into body cells and stimulates the liver and muscle cells to store glucose as glycogen. As a result, blood glucose level drops. 2 Glucagon promotesthe breakdown ofglycogen in theliver and the release of glucose into the blood, increasing bloodglucose level. 4 When blood glucose level drops, the pancreas secretes the hormone glucagon, which opposes the effect of insulin. 3 Glucose • Human body regulates the use and storage of glucose. STIMULUS: Blood glucose level rises after eating. Homeostasis: 90 mg glucose/ 100 mL blood STIMULUS: Blood glucose level drops below set point. Figure 41.3

17. Stores of glycogen and fat are used up – so what is left? Undernourished – calorie deficient Overnourished – calorie excess

18. Neuropeptide Y Hypothalamic feeding center Negative feedback  Food intake  Fat stores     Leptin secretion   

19. Neuropeptide Y Hypothalamic feeding center X Negative feedback  Food intake  Fat stores    X  Leptin secretion   

20. Secreted by the stomach wall, ghrelin is one of the signals that triggers feelings of hunger as mealtimes approach. In dieters who lose weight, ghrelin levels increase, which may be one reason it’s so hard to stay on a diet. Produced by adipose (fat) tissue, leptin suppresses appetite as its level increases. When body fat decreases, leptin levels fall, and appetite increases. Ghrelin Insulin Leptin PYY The hormone PYY,secreted by the small intestine after meals, acts as an appetite suppressant that counters the appetite stimulant ghrelin. A rise in blood sugar level after a meal stimulates the pancreas to secrete insulin (see Figure 41.3). In addition to its other functions, insulin suppresses appetite by acting on the brain. Hormones and Appetite Figure 41.5

21. Malnourished – diet is missing one or more essential nutrients Materials that must be obtained in their preassembled form because animal cells cannot make them from any raw material Osteophagia – bone eating

22. Essential Nutrients Essential amino acids Essential fatty acids Vitamins Minerals In order for protein synthesis to occur in human adults, eight amino acids must be available simultaneously and in the correct relative amounts Important for phospholipid membrane; and principal storage compound Organic molecules in small amounts Inorganic molecules in small amounts Water soluble Fat soluble

23. Food Processing Ingestion Digestion Absorption Elimination Act of eating Process of breaking food down into molecules small enough for the body to absorb Take up small molecules from the digestive compartment Undigested material passes out of the digestive compartment Intracellular Extracellular

24. Campbell; Fig.41.10 Food Processing Digestion Process of breaking food down into molecules small enough for the body to absorb Intracellular Extracellular

25. Campbell; Fig.41.11 Food Processing Digestion Process of breaking food down into molecules small enough for the body to absorb Intracellular Extracellular Gastrovascular cavity Complete digestive tract or alimentary canal

26. Campbell; Fig. 33.4 Campbell; Fig. 33.10

27. Campbell; Fig. 41.13

28. Campbell; Fig.41.12a

29. Campbell; Fig.41.12b

30.  Highly reliant on digestive system to remain healthy  Cannot afford to store heavy materials in body for lengthy period Campbell; Fig.41.12c

31. Mouth – usually • relatively simple • Esophagus – may be widened at • midpoint to form crop (storage area) • Proventriculus – glandular • stomach which is highly acidic 4. Gizzard – thick muscular walls and sandpaper like surface stomach 5. Small intestine – food digestion and absorption • Caecum – bacterial breakdown • of cellulose 7. Large intestine 8. Cloaca – final holding area

32. Proctor and Lynch; Manual of Ornithology

33. EVOLUTIONARY ADAPTATIONS OF VERTEBRATE DIGESTIVE SYSTEMS • Length of digestive system • Accessory structures (such as) • Crop • Gizzard • Liver • Caeca Campbell; Fig. 41.21

35. EVOLUTIONARY ADAPTATIONS OF VERTEBRATE DIGESTIVE SYSTEMS Dentition Many kinds of animals have tooth–like structures, but only vertebrates have true teeth, with an ultra-hard layer of ENAMEL on the outside and softer DENTINE on the inside. Campbell; Fig. 41.20

36. The incisors in blue (cutting plant food) The canines in red (slicing and tearing meat) The molars in green (grinding grass and other plants) http://www.oum.ox.ac.uk/children/animals/nuteeth.htm

37. http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/kinds_of_teeth.htmlhttp://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/kinds_of_teeth.html

38. Examples of modified incisors

39. EVOLUTIONARY ADAPTATIONS OF VERTEBRATE DIGESTIVE SYSTEMS Use of Symbiotic Microorganisms Campbell; Fig. 41.22 X cellulase cellulose

40. Campbell; Fig.41.22

41. Four compartment stomach • Reticulum – form • food bolus and initiate • regurgitation Reticular epithelium – honeycomb lining

42. Four compartment stomach • Reticulum – form • food bolus and initiate • regurgitation Rumen Interior • Rumen – digestive • and fermentation vat • containing anaerobic • microbes and site • of fatty acid absorption

43. http://www.borderouge.com/photos/chai.jpg

44. Four compartment stomach • Reticulum – form • food bolus and initiate • regurgitation • Rumen – digestive • and fermentation vat, • contains anaerobic • microbes, site • of fatty acid absorption 3. Omasum – lined by muscular folds, reduces particle size, absorbs water (and any leftover fatty acids) Omasum epithelium

45. Four compartment stomach • Reticulum – form • food bolus and initiate • regurgitation • Rumen – digestive • and fermentation vat, • contains anaerobic microbes, • site of fatty acid absorption • Omasum – lined by muscular • folds, reduces particle size, • absorbs water (and any • leftover fatty acids) • Abomasum – true • glandular stomach where • bacteria and pathogens • are killed

46. What do the microbes provide to the ruminants? Symbiotic Microorganisms 1. Digestion of cellulose 2. Provision of organic acids 3. Provision of protein 4. Provision of B vitamins 5. Detoxify compounds

47. What do the ruminants provide to the microbes? Symbiotic Microorganisms 1. Housing with reliable heat 2. Adequate nutrition 3. Garbage removal 4. Neutral environment

48. EVOLUTIONARY ADAPTATIONS OF VERTEBRATE DIGESTIVE SYSTEMS • Foregut fermenters • a. Cows, sheep, goats • Hindgut fermenters • Horses, rodents, rabbits • Coprophagy • Using feces as a nutritional resource • Food passes through entire digestive tract a second time Campbell; Fig. 41.21