Animal Nutrition

1. Animal Nutrition Chapter 41

2. Nutrition • Intake of food from external environment • A balanced diet provides fuel for cellular work and the materials needed to construct organic molecules • Proper diet needed in order to maintain homeostasis (balanced internal environ.)

3. Nutrition • Nutrition satisfies three needs of animals: • fuel (chemical energy) for metabolism • the organic raw materials (carbon skeletons) • essential nutrients • substances animals can’t make themselves from any raw material • must obtain in food from environment

4. Energy (ATP) • Remember, cell resp. releases ATP by oxidizing food molecules • ATP powers basal or resting metabolism, as well as activity, and, in endothermic animals, temperature regulation

5. Biosynthesis and Energy Storage • More calories than needed to produce ATP, excess can be used for biosynthesis • growth in size, reproduction, or stored in energy depots • In humans, the liver and muscle cells store energy as glycogen (polymer of glucose units) • If glycogen stores are full and caloric intake still exceeds caloric needs, excess stored as fat • Basis for recent low-carb diet trend

6. Regulation of Glucose Levels (ie: blood sugar) • High Glucose (High Blood Sugar) • Pancreas secretes insulin • promotes glucose storage as glycogen in liver/muscles) • Low Glucose (Low Blood Sugar) • Pancreas secretes glucagon • promotes the breakdown of glycogen and release of glucose into blood

7. Glucose Regulation (Pancreas)

8. Undernourishment • When not receiving enough calories, the body breaks its energy stores down • Body first depends on liver stores, then muscle and fat glycogen • Average adult has enough fat stores for weeks of starvation • Severe malnutrition leads to loss of muscle mass and loss of brain proteins • Brain damage, death, or permanent disability possible

9. Overnourishment • Leads to obesity (excess fat stores) • Leads to serious health issues, especially cardiovascular disease and death • Excess carbs leads to storage as fat molecules • Hormones are involved in the regulation of fat storage

10. You are What you Eat • In addition to needing energy, you must take in certain molecules needed as raw materials (mostly C-skeletons) for important biomolecules • essential nutrients • must obtain from environment • Can’t make on their own • Species specific • Ex: vitamin C not important in all species, very important in humans

11. Malnourishment • Diet lacking in one or more essential nutrients • Even possible for an overnourished individual to be malnourished • Much more common in humans than undernourishment

12. Amino Acids • Animals require about 20 amino acids for protein synthesis • Can make about half from raw materials (provided enough nitrogen) • Essential Amino Acids Must be obtained in preassembled form • Protein deficiency • Missing one or more amino acids in diet • Most common form of malnourishment

13. Complete/Incomplete Proteins • Complete Proteins • Provide all essential amino acids • Meat, eggs, cheese (animal products) • Incomplete Proteins • Lacking one or more essential amino acids • Corn, rice, etc all lack an essential amino acid • Staples in 3rd World Countries

14. Overcoming Incomplete Proteins • Eat a complementary mix of veggies that cover the essential amino acids • Eating the right mix of incomplete proteins is as effective as eating complete proteins

15. Fatty Acids • Most fatty acids can be synthesized • There are a few essential fatty acids (usually unsaturated) • Deficiencies are rare

16. Vitamins • Required in relatively trace (minimal) amounts • However, deficiencies can have drastic effects • 13 vitamins essential to humans • water-soluble vitamins • fat-soluble vitamins

17. Water Soluble Vitamins

18. Fat Soluble Vitamins

19. Minerals • Simple inorganic nutrients • Usually required in small amounts • Ex: Ca+2 and PO4-3 required for bones • Ex: Iron needed for hemoglobin, cytochrome complex (ETC) • Na+,K+ and Cl- needed for osmotic balance and transport

20. Minerals

21. Types of Nutrition • Herbivores (gorillas, cows, hares)  eat mainly autotrophs (plants, algae) • Carnivores (sharks, hawks, spiders, and snakes)  eat other animals • Omnivores (humans)  consume animal and plant or algal matter

22. Suspension Feeders • sift small food particles from the water • Ex: baleen whales, clams

23. Deposit Feeders (e.g., earthworms) • Eat their way through dirt or sediments extract partially decayed organic material consumed along with the soil or sediments

24. Substrate Feeders • Live in or on their food source • Ex: Maggots consuming a decaying carcass • Ex: Leaf Miner (right) burrows through leaf

25. Fluid Feeders • Suck nutrient-rich fluids from a living host • Often considered parasites • Ex: Mosquitoes and leaches suck blood from animals • Ex: Aphids tap the phloem sap of plants • Ex: Hummingbirds and bees are good fluid feeders (nectar)

26. Bulk Feeders • Most animals eat relatively large portions of food when available • This is sort of a take it while you can get it approach to nutrition b/c food can be scarce

27. Ingestion  Take Food In • Act of eating • First stage of food processing • Food molecules cannot be used “as-is” and must be digested in order for the cells to make use of them as nutrients

28. Digestion  Break Food Down • Why is food digested?? • Polymers in food molecules too large to pass into cells • Macromolecules in food are not exactly what makes up the animal eating them • However, animals all use common monomers to assemble macromolecules

29. Digestion • Break food down into small, absorbable molecules • Polysaccharides and disaccharides are split into simple sugars. • Fats are digested to glycerol and fatty acids. • Proteins are broken down into amino acids. • Nucleic acids are cleaved into nucleotides

30. Enzymatic Hydrolysis • Reverse process as dehydration synthesis • Enzymes are used to cleave polymers into monomers • Specific enzymes digest the specific classes of macromolecules • Chemical digestion (enzymes) is generally preceded by mechanical digestion (chewing, gizzard)

31. Absorption and Elimination • Useful nutrient molecules are absorbed and used by the animal • Molecules that have little use in the organism are eliminated as waste

32. Digestion • Specialized organs perform the various digestion of food molecules • Keeps organisms from digesting their own cells Intracellular Digestion • Food vacoules break down particles via hydrolytic enzymes • Sole digestion of many protists

33. Food Vacuole Digestion

34. Extracellular Digestion • Takes place outside of cells • Fungi release enzymes into the soil that digest their food before it enters them • Allows smaller single-celled organisms to consume larger food molecules than phagocytosis

35. Gastrovascular Cavities • Single opening digestive systems • Food enters mouth, is digested in GV cavity, and undigested material is eliminated back through the mouth • Cnidaria, flatworms

36. Alimentary Canals (complete digestive tube) • Mouth, digestive tube (stomach, gizzard, intestines), and anus • Runs in one direction, food processed differently in different compartments • Mouth  Pharynx  Esophagus  Crop/Gizzard/Stomach (species dep.) Intestines  Anus

37. Alimentary Canals

38. Human Digestion • 5 to 10 seconds in esophagus • 2 to 6 hrs in the stomach being partially digested • 5 to 6 hrs in small intestine (final digestion and nutrient absorption) • 12 to 24 hours after consumption, undigested material eliminated through large intestine and anus

39. Human Digestive System

40. Levels of Organization • Cells are the basic functional unit • Cells  Tissues  Organs  Organ Systems  Organism

41. Tissues • Epithelial tissue covers the surface of the body and lines the inside of organs • simple epithelium - single layer of cells;stratified epithelium - multiple tiers of cells • The shapes of cells: cuboidal (like dice)columnar (like bricks on end) squamous (flat like floor tiles)

43. Muscles • Many muscles are involved in digestion • Some are voluntarily controlled (skeletal muscle) and others are involuntarily controlled (smooth muscle) • Skeletal  Striated, voluntary, found in muscles and other voluntarily controlled sphincters • Smooth  Not striated, involuntary, peristalsis • Cardiac  Found in the heart, involuntary

45. Oral Cavity (Mouth) • Begins physical (chewing) and chemical digestion of food • Salivary amylase breaks down starch • Enzyme released in response to food presence • Chewing increases surface area for chemical digestion • Saliva also lubricates food for passage through esophagus

46. Pharynx • Between the mouth and the esophagus • Epiglottis  Flap of skin that keeps the bolus (food ball) from “going down the wrong pipe” • When swallowing, the epiglottis covers the trachea and diverts food into the esophagus

47. Epiglottis

48. Esophagus • Top muscles are voluntary (part of swallowing you control) • Involuntary series of muscle contractions (peristalsis) move food from mouth to stomach after it passes into esophagus from pharynx

49. Stomach • Chemical and mechanical digestion (involuntary) proceed in the stomach • Elastic walls and folds allow the stomach to churn about 2 L of food/liquid at a time • Secretes gastric juice (pepsin + HCl) that chemically digests

50. Gastric Juice • HCl provides acidic environment for pepsin and kills bacteria ingested with food • HCl converts pepsinogen (inactive) to pepsin (active) • Pepsin is an enzyme that hydrolyzes proteins • Chief cells secrete pepsin • Parietal cells secrete HCl