Chapter 50 Animal Nutrition

1. Chapter 50 Animal Nutrition Biology 102 Tri-County Technical College Pendleton, SC

2. Diet and Energy Requirements • Fuel (chemical energy) needed for cellular respiration • Raw organic materials for biosynthesis • Essential nutrients MUST be obtained in prefabricated form • Metabolic rate is measure of overall energy needs that must be met by ingestion and digestion of food

3. Requirements, cont. • BMR (Basal metabolism rate) defined as rate resulting from all essential physiological functions of resting person • BMR is about 1300-1500 kcal/day for adult female and 1600-1800 kcal/day for adult male • Physical activity adds to this requirement • Calorie (c) or Kcalorie (C) used to measure amounts of energy in foods • Fats (9.5); carbs (4.2), and proteins (4.1) • ISU unit of joule where 1 c = 4.184 joules

4. But I am really hungry… • Undernourished person or animal is one whose diet is deficient in calories • This is really iffy…NCTR data now 10 years + • Malnourished person or animal is one whose diet is missing one or more essential nutrients • Depending on which nutrient, might be more damaging than calorie deficiency

5. Essential Nutrients…and more • Essential amino acids are those that must be obtained in diet in prefabricated form • In humans, eight are essential; can manufacture the other 12 given precursors • Protein deficiency results when diet lacks one or more essential amino acids • Human body CANNOT store essential AAs • Deficiency retards protein synthesis

6. Essential Nutrients, cont. • Essential fatty acids are those unsaturated fatty acids that cannot be produced by body • Linoleic acid is example in humans • Required to produce phospholipids for membranes • Fatty acid deficiencies are rare • Vitamins are organic molecules required in diet in much smaller quantities than essential AAs/Fatty acids • May serve a catalytic function • Vitamin deficiencies may cause very severe effects

7. Essential Nutrients, cont. • Water soluble versus fat soluble vitamins • If body of animal can synthesize a certain compound, it is NOT a vitamin • Minerals are inorganic nutrients required in diet in small quantities ranging from 1 mg to 2500 mg/daily • Some serve structural/maintenance roles • Calcium and phosphorous • Others serve as parts of enzymes (copper) or other molecules (iron)

8. Water, water everywhere… • Water soluble vitamins are NOT stockpiled in body tissue so excesses excreted in urine • Includes B complex vitamins functioning as coenzymes in key metabolic processes • Includes vitamin C required for synthesis of connective tissue/antioxidant • Fat soluble vitamins are stockpiled in body tissues; excesses NOT excreted by body but deposited in body fat • Overdoses may result in accumulation to toxic levels

9. Vitamins, cont. • Fat soluble vitamins are A, D, E, and K • A incorporated into visual pigments of eye • D aids in calcium absorption/bone formation • E is antioxidant for phospholipids • K required for blood clotting

10. Mineral mine…so to speak • Calcium found in dairy products, dark green veggies, and legumes • Needed for bone formation, blood clotting, & nerve and muscle functioning • Phosphorous found in dairy products, meats, and grains • Needed for bone/tooth formation, acid-base balance, & nucleotide synthesis

11. Minerals, cont. • Sulfur: proteins from many sources • Is component of certain amino acids • Potassium: meats, dairy products, many fruits and veggies, and grains • Important in acid-base balance, water balance, & nerve function • Chlorine found in table salt • Acid-base balance, formation of gastric juice, nerve function, & osmotic balance

12. Minerals III • Sodium found in table salt • Acid-base balance, water balance, & nerve function • Magnesium: whole grains, green, leafy veggies • Is cofactor and component of ATP bioenergetics • Iron: meats, eggs, legumes, whole grains, green, leafy veggies • Hemoglobin, electron carrier in metabolism, & enzyme cofactor

13. Animal Adaptations • Animals are chemoheterotrophs (eat plants and other animals, maybe…) • Herbivores eat autotrophic organisms (plants, algae, & autotrophic bacteria) • Carnivores eat other animals • Omnivores eat other animals and autotrophs • Animals evolved diversity of adaptations to exploit, directly/indirectly, resources made available by autotrophs

14. Adaptations, cont. • Filter-feeding (suspension): sift small food particles from the water (clams/oysters; baleen whales) • Substrate-feeding: live on or in food source and eat way through food (leaf miners tunnel through interior of leaves) • Deposit-feeding: type of substrate-feeder that ingests partially decayed organic materials along with their substrate (earthworm ingests soil and digestive system extracts organic materials

15. Adaptations, III • Fluid-feeders: suck nutrient-rich fluids from a living host (aphids ingest phloem sap; leeches and mosquitoes suck blood, hummingbirds & bees ingest nectar • Bulk-feeders: eat relatively large pieces of food

16. I can’t believe I ate… • Digestion is process of breaking down food into small molecules body can absorb • Macromolecules are TOO large • Digestion enzymatically cleaves them into monomers that can be used by animal • Poly/Disaccharides into simple sugars • Proteins into amino acids • Fats into glycerol and fatty acids

17. Say what??? • Gastrovascular cavity is digestive sac with single opening; functions in both digestion and nutrient distribution (Incomplete digestive tract) • Most animals with simple body plans have GV cavity • Extracellular digestive cavities are advantageous because allow ingestion of larger food items that can be phagocytosed and digested intracelluarly • Phylum Cnidaria (Hydra) and Phylum Platyhelminthes (planarians)

18. Complete Digestive Tract • CDT (alimentary canal) is digestive tube running between two openings; the mouth (food ingested) and anus (undigested wastes eliminated) • Food moves in one direction along tube • Tube can be organized into specialized regions for digestion and absorption on nutrients in stepwise fashion • Unidirectional passage of food/specialization of function makes alimentary canal more efficient • Phylum Nematoda, Annelida, Mollusca, Arthropoda, Echinodermata, and Chordata

19. Tummy growling? • Peristalsis is rhythmic smooth muscle contractions • Pushes food along alimentary tract • Alimentary tract lined with both circular and longitudinal muscle bundles • Wow, time for an Estesism

20. Vertebrate Digestive Tract • Teeth adapted for acquisition/initial processing of specific types of food • Tear, shred, grind, and pulverize food • Food chewed and mixed with secretions of salivary glands • Esophagus is food tube connecting mouth to stomach • Peristalsis moves food down esophagus • Esophageal sphincter normally prevents food from exiting stomach back into esophagus

21. VDT, cont. • Stomach stores food consumed • Secretions kill most microorganisms and begins digestion of proteins • Processed into chyme, pyloric sphincter allows passage into small intestine • Small intestine is major site of digestion • Protein/carbs continue; fat digestion begins • Absorption of nutrients begins

22. VDT III • Duodenum site of most digestion; jejunum and ileum responsible for ~ 90% absorption of nutrients • Large intestine (colon) absorbs water and ions • Immense populations bacteria live in colon • Vitamin K, biotin, methane, and hydrogen sulfide • Feces stored in last segment and excreted • Too much water, too little water…oh yeah!!!

23. VDT IV • Appendix can be source of difficulty • Rectum is terminal portion of large intestine • Ends at the anus • Site of fecal storage until elimination is convenient (that’s the hope)

24. Digestive Enzymes • Macromolecules (protein, carbs, and fats) must be broken into their monomers by hydrolytic enzymes • Hydrolysis occurs by adding water molecules • Digestive enzymes classified according to substances they hydrolyze

25. Digestive Enzymes, cont. • carbohydrasescarbs; proteasesprotein; peptidasespeptides; lipasesfats; nucleasesnucleic acids • Exo and endo indicate where enzyme cleaves the molecule • Example: endoprotease hydrolyzes a protein at an internal site along the polypeptide chain

26. Salivary Amylase • Secreted with saliva • Begins starch digestion into glucose in mouth • Bread and crackers begin to taste “sweet” if held in mouth long enough • Starch digestion continues in duodenum where pancreatic amylases hydrolyze starch and glycogen into disaccharides

27. Pepsin • Major enzyme produced by stomach is endopeptidase called pepsin • Secreted as zymogen (pepsinogen) by gastric glands in stomach lining (chief cells) • Along with HCl of stomach, begins protein digestion • Splits peptide bonds next to some AAs • Begins process of “unwinding” proteins creating more surface area for other enzymes to act upon

28. Pancreatic Enzymes • Pancreas functions as both endocrine and exocrine gland • Exocrine products delivered to gut via pancreatic duct • Produces host of digestive enzymes: • Pancreatic amylase, lipase, nuclease, trypsin, chymotrypsin, and carboxypeptidase

29. Stomach tough as nails… • Stomach has pH of about 2 • Acidic enough to dissolve iron nails • Function is to disrupt extracellular matrix that binds cells together in meat and plant material • Also kills most (but not all) of bacteria that are swallowed with food • Also produces bicarbonate buffer for neutralizing acidic chyme as exits stomach

30. Event Sequencing • Duodenum is first 25 cm of small intestine • >ed delivery of acid chyme to duodenum stimulates production of secretin by duodenum wall (enterogastrone) • Secretin simulates bicarbonate release from pancreas • Gallbladder stores bile produced by liver • Bile does NOT contain digestive enzymes

31. Sequencing, cont. • Bile does contain bile salts which emulsify fat • Contains pigments (byproducts of destroyed RBCs) • Cholecystokinin (CCK) produced by duodenum wall stimulates pancreas to release pancreatic enzymes into small intestine & gall bladder to contract and release bile into small intestine

32. Sequencing III • Other enterogastrones (secreted by wall of duodenum) inhibit peristalsis in stomach • This, in effect, slows food entry into small intestine • Meanwhile, back at the ranch, it’s a razing stampede of mugwomps and widgets…just look at that mess!!!!

33. Digesting Digestion…what fun • Carbohydrate digestion begins in mouth and again in duodenum (salivary vs. pancreatic amylases • Disaccharidases attached to surface of duodenal epithelium hydrolyze disaccharies into monosaccharides • Each disaccharide has its own disaccharidase

34. DD, cont. • Maltose/maltase; sucrose/sucrase; lactose/lactase • Occurs in epithelial brush border of small intestine • Since disaccharides are on surface of epithelim, final breakdown of carbs occurs where sugars will be absorbed

35. Digesting, III • Pepsin begins protein digestion in stomach • Pancreas secretes enteropeptidase • Converts trypsinogen to trypsin • Chymotrypsin is also produced • Both specific for peptide bonds adjacent to certain AAs; break large polypeptides into smaller chains

36. Digesting IV • Carboxypeptidase (exopeptidase) splits AAs one at time, off PP end that has free carboxyl group • Lining of small intestine secretes protein digesting enzymes • Aminopeptidase splits one AA at time from PP end that has free amino group • Dipeptidases attached to intestinal lining split small PPs

37. Enough of this digesting..already • Trypsin, chymotrypsin, & carboxypeptidase are secreted in inactive form by pancreas • Aminopeptidase, dipeptidase, & enteropeptidase are secreted by lumen of small intestine • Pepsin secreted by stomach • Trypsin, chymotrypsin, aminopeptidase, & carboxypeptidase secreted by lumen of small intestine • Dipeptidases secreted by epithelium of small intestine (Brush border)

38. Digesting Nucleic Acids • Also involves teams of enzymes • Nucleases hydrolyze DNA and RNA into nucleotides • Occurs in lumen of small intestine • Other hydrolytic enzymes (nucleotidases and nucleosidases) break nucleotides into nucleosides and nitrogenous bases, sugars, and phosphates

39. Pass the butter, please? • Fat digestion occurs ONLY in lumen of small intestine • Emulsification produces many small fat droplets that have large surface area for digestion • Pancreatic lipase (from duodenum) hydrolyzes fats into glycerol and fatty acids • Peristalsis moves digestive enzymes-chyme mixture through the duodenum (poly into mono)

40. Bitter as bile… • Bile is produced by liver and store in gall bladder • Acts as detergent and aids in digestion and absorption of fats • Also contains pigments that are by-products of red blood cell destruction in the liver • “Funny tasting chicken liver…you bet!!!!

41. And finally, brethren… • Most nutrient absorption occurs in jejunum and ileum of small intestine • Large folds increase surface available for absorption • Many villi (projections from surface) increase SA of small intestine • Villi covered with microscopic microvilli which > surface area for contact with contents and absorption (300 m2) • Most water reabsorbed in large intestine (colon)

42. Call it like it is… • Feces is wastes of the digestive tract moved through tract by peristalsis • Intestinal bacteria live on organic material in feces • Produce some vitamin K (mutualism) • Feces may contain abundance of salts • Stored in rectum and passes through 2 sphincters; 1 voluntary and 1 involuntary to anus for elimination • Literally…the end