Unit 1: Nutrients & Digestion

1. Unit 1: Nutrients & Digestion Chapter 1

2. Unit 1: Nutrients & Digestion • Unit 1 Objectives: • Review the 6 basic nutrients and investigate their function • Revisit the various digestive systems • Comprehend the functions of the digestive anatomy of monogastrics and ruminants

3. Unit 1: Nutrients & Digestion • Water • Cheapest, most abundant, most important nutrient • Constitutes 45-85% of animal body weight • decreases with age • 90-95% of blood • tissue is 70-90% water

4. Unit 1: Nutrients & Digestion • Three forms in the body • Intracellular • muscle and skin • Extracellular • interstitial fluids, lymph, cerebrospinal fluid, blood plasma • Urinary and GI water

5. Unit 1: Nutrients & Digestion • Functions of Water • transportation of nutrients and excrement • chemical reactions • temperature regulation • shape • lubrication • Water Deficiencies • reduced feed intake • weight loss/dehydration • increased excretion of N and electrolytes

6. Unit 1: Nutrients & Digestion • Water sources • Drinking water • temp/humidity affect consumption • dietary water affects consumption • productivity of the animal affects consumption • Water quality is crucial • Consumption rates • Swine-2.5-5g/d • Sheep-1-4g/d • Cattle-8-16g/d (may be significantly more in lactation) • Horses-10-14g/d

7. Unit 1: Nutrients & Digestion • Water loss • urination • fecal • vaporization from lungs or through skin • sweat • Water absorption • Readily absorbed from virtually all sections of the GI tract • rumen, omasum, ileum, jejunum, cecum, LI

8. Unit 1: Nutrients & Digestion • Amount absorbed • varies w/ species and diet • indigestible dietary fiber can reduce absorption • can be reduced by the amount of dietary pectins, toxins, and stressors • Carbohydrates (CHO) • Consist of Carbon, Hydrogen, Oxygen

9. Unit 1: Nutrients & Digestion • Includes: • sugars • starches • cellulose • gums • CHO makes up 3/4 of plant dry wt.

10. Unit 1: Nutrients & Digestion • Classified by the number of sugar molecules • Monosaccharides • glucose • most important sugar in nutrition • primary form used for energy • fructose • Disaccharides • sucrose • maltose • lactose • milk sugar

11. Unit 1: Nutrients & Digestion • Polysaccharides • starch • principle sugar form in cereal grains • cellulose • 25-30% of fibrous plants • most abundant CHO in nature • hemicellulose • main component of plant cell walls • can only be degraded by microbial enzymes • complex mixture of sugars

12. Unit 1: Nutrients & Digestion • Non-carbohydrate • Lignin • covers cellulose and hemicellulose to increase rigidity of plant cell walls • as level increases, digestibility decreases • cannot be broken down by any animal or bacterial enzyme • Functions • source of energy and heat • building blocks for other nutrients • stored by converting to fat

13. Unit 1: Nutrients & Digestion • Deficiencies • Ketosis • common in animals requiring high amounts of energy • can have a “snowball” effect • increases breakdown of protein for energy • loss of BW • decreases milk production • can cause abortion • distinct smell of acetone

14. Unit 1: Nutrients & Digestion • Diabetes • more common in humans • insufficient insulin production by the pancreas • can be genetically related • Digestion & Metabolism • Crude Fiber • cellulose, hemicellulose, lignin • Poorly digested • Nitrogen-Free Extract • soluble sugars, starches • readily digested

15. Unit 1: Nutrients & Digestion • Converted to Adenosine Triphosphate (ATP) • the energy currency of the body • drives all physiological processes that require energy • 1 molecule of glucose will yield 38 ATP’s through various oxidative pathways • Lipids • Can be soluble or insoluble depending on what they’re mixed with

16. Unit 1: Nutrients & Digestion • Classification • Simple Lipids • true fats • waxes • Compound Lipids • Lipoproteins • Glycolipids • LDL, VLDL, HDL • Derived Lipids • Sterols • Cholesterol

17. Unit 1: Nutrients & Digestion • Fatty Acids • Essential Fatty Acids • linoleic, linolenic acids • Protein • Main component of organs and soft structures in the animal body • Dietary requirement is highest in young animals • Proteins are very large molecules

18. Unit 1: Nutrients & Digestion • Protein structure • made up of very simple units called Amino Acids (AA) • arrangement of AA in the chain and the length of the chain determine the composition of the protein • 22 AA are commonly found in proteins • linked together by peptide bonds

19. Unit 1: Nutrients & Digestion • Levels of Protein structure • Primary Structure • individual AA linked by peptide bonds to form a polypeptide chain • Secondary Structure • twisted polypeptide chain • H bonds link helical structures together • Tertiary Structure • helical structures fold into rigid layers

20. Unit 1: Nutrients & Digestion • Quaternary Structure • several tertiary structures linked together • very large proteins • Importance of protein structure • biological activity of the protein related to the level of the protein • Denaturation • loss of protein structure • caused by heat • loses biologic activity, but may increase digestibility

21. Unit 1: Nutrients & Digestion • Maillard Reaction • caused by excess heat • excess heat may be caused by improper storage, cooking, drying, etc. • can severely decrease digestibility • Protein Terminology • True Protein • made up only of AA • Nonprotein Nitrogen (NPN) • not true protein compounds, but contain N, and can be converted to protein • ex.?

22. Unit 1: Nutrients & Digestion • Crude Protein • total protein from true and NPN sources • CP = %N x 6.25 • Digestible Protein • portion of CP that can be digested • difference between fed protein and fecal protein • Essential AA • essential to the animal, and must be supplied in the diet b/c the animal cannot synthesize them fast enough to meet the requirement • PVT TIM HALL

23. Unit 1: Nutrients & Digestion • Phenylalanine, Valine, Threonine, Tryptophan, Isolecine, Methionine, Histidine, Arginine, Leucine, Lysine • Functions • Basic structural units of the body • collagen • keratin • blood proteins • Body Metabolism • enzymes, hereditary transmission • hormones, immune antibodies

24. Unit 1: Nutrients & Digestion • Deficiencies • reduced growth rate, and feed efficiency • infertility, fatty liver, lack of hormone/enzyme production • deficiencies/imbalances in AA will decrease production • Natural Sources • most feeds contain protein • quantity and quality of protein may be highly variable

25. Unit 1: Nutrients & Digestion • Digestion & Metabolism • dietary proteins must be broken down to AA form for absorption • except in early postnatal mammals • in the stomach, proteins are broken down to: • dipeptides • tripeptides • free AA

26. Unit 1: Nutrients & Digestion • Absorption of proteins • Free AA • absorbed by active transport (requires energy) • occurs in the SI • Di- & Tripeptides • absorbed by mucosal cells in the SI in • will still be changed to FAA • Whole Proteins • engulfed by mucosal cells • only happens in newborn mammals (24-48 hrs.), absorb antibodies from colostrum

27. Unit 1: Nutrients & Digestion • Minerals • total mineral content of plants often referred to as Ash • constitutes 3-5% of animal body dry wt. • Classification • Macrominerals • present/required in greater levels • Ca, P, K, Mg, Cl, S, Na

28. Unit 1: Nutrients & Digestion • Microminerals • present/required in small amounts • Co, Cu, I, Fe, Mn, Mo, Se, Zn • Functions • skeletal formation and maintenance • active in protein synthesis • oxygen transport • fluid balance, and pH • activates or components of enzyme systems

29. Unit 1: Nutrients & Digestion • Natural Sources • forage plants are good natural sources • may be somewhat variable • Digestion & Metabolism • absorbed in the SI in ionic form • active transport (Ca, P, Na) or diffusion • mineral absorption can vary due to: • age of the animal • form of the element, binding/chelation, excesses or interactions of minerals • pH of GI tract

30. Unit 1: Nutrients & Digestion • Vitamins • present and active in small amounts • essential for tissue development and immune function • most cannot be synthesized, and must be supplemented in the diet

31. Unit 1: Nutrients & Digestion • Classification • Fat-soluble • Vitamins A, D, E, K • regulate metabolism of structural units • absorbed in the SI in the presence of fat • Water-soluble • Thiamine, Riboflavin, Niacin, Biotin, Choline, Folic Acid, B12, etc. • concerned with the transfer of energy • absorbed with intestinal water

32. Unit 1: Nutrients & Digestion • Digestion & Metabolism • little is known about vitamin digestion • most absorbed in the upper portion of the intestine • B12 is absorbed in the ileum • water-soluble are readily absorbed • fat-soluble vitamin absorption depends on fat absorption (a slow process)

33. Unit 1: Nutrients & Digestion • Nutrients in Metabolism • Maintenance • Heat for temp regulation • energy for internal work • minimum movement • tissue repair • greatest requirement for energy • Growth • protein, energy and other nutrients required for structural growth

34. Unit 1: Nutrients & Digestion • Especially critical when another bodily work is ongoing • lactation, work etc. • growth will be sacrificed in the presence of another need • Work • mostly requires energy and water • Reproduction • minimal requirements • over or under-conditioning can reduce efficiency

35. Unit 1: Nutrients & Digestion • Lactation • very high nutritional demand • best to feed for lactation demand rather than build up bodily stores • Fattening • high energy to protein ratio required • body will meet all other needs first • Called Nutrient Partitioning

36. Unit 1: Nutrients & Digestion • Requirements can vary • state of growth or age • size of animal • environment • heredity • disease • activity • degree of condition • ration imbalances • species

37. Unit 1: Nutrients & Digestion • Digestive Systems • terms to know: • Prehension-taking in feed/water • Mastication-chewing, reducing particle size • Deglutition-swallowing • Regurgitation-casting up of undigested material • Digestion-breakdown of feed to products for absorption • mechanical, chemical, or enzymatic activity

38. Unit 1: Nutrients & Digestion • Absorption-transfer of nutrients from GI to blood/lymph • Anabolism-growth or building process • Catabolism-breakdown of structures • Metabolism-combination of anabolism & catabolism processes in order to create energy • Excretion-elimination of wastes

39. Unit 1: Nutrients & Digestion • Monogastric Digestive System • Mouth • what is contained, and what is their functions? • Saliva • water-moistens food, aids in taste • mucin-lubrication for swallowing • Bicarbonate salts-buffer to regulate pH • enzymes-amylase can begin breakdown of CHO (only in some species)

40. Unit 1: Nutrients & Digestion • Esophagus • tube for transport from mouth to stomach • moved by muscular contractions called Peristalsis • Stomach • Cardia-sphincter at junction of esophagus and stomach that regulates passage into/out of stomach • Esophageal Region-nongladular, surrounds the cardia

41. Unit 1: Nutrients & Digestion • Cardiac Gland Region-produces mucus that protects stomach lining • Fundic Gland Region-produces gastric secretions needed to stimulate digestion • hydrochloric acid, and enzymes • Pyloric Gland Region-mucus and proteolytic enzymes • Pylorus-sphincter controlling passage of digesta to intestine

42. Unit 1: Nutrients & Digestion • Functions • feed storage • physical breakdown of material by muscular movement • secretion and regulation of “gastric juices” • acid • pepsinogen • mucus • rennin • material leaving stomach now called chyme

43. Unit 1: Nutrients & Digestion • Small Intestine • Duodenum • receives secretions from pancreas, liver, • active site of digestion • Jejunum • active in nutrient absorption • Ileum • also active in nutrient absorption • walls lined with villi and microville that increase surface area for absorption

44. Unit 1: Nutrients & Digestion • Bile • synthesized by the liver, stored in the gall bladder • emulsifies fats for absorption • activates pancreatic enzymes • much is recycled • Pancreatic Juice • buffers • digestive enzymes

45. Unit 1: Nutrients & Digestion • Large Intestine • Cecum • size, and function can vary • Colon • largest part • Rectum • final section • Function • water resorption • can be storage of undigested nutrients

46. Unit 1: Nutrients & Digestion • Can be site of bacterial fermentation • limited site of nutrient absorption • Horse • Saliva • no enzymes • scratching from forages stimulates secretions • produce ~10g/d • Esophagus • 50-60” long • one-way peristaltic movements

47. Unit 1: Nutrients & Digestion • Stomach • relatively small stomach, meals must be small • little muscular movement • Small Intestine • no gall bladder to store bile for secretion to SI • Large Intestine • 60% of GI

48. Unit 1: Nutrients & Digestion • Cecum & Large Colon • active bacterial population • breakdown of cellulose and other CHO’s to Volatile Fatty Acids (VFA) acetate, propionate, butyrate for use as energy • synthesize protein and water-soluble vits. • Small Colon • primary site of water resorption

49. Unit 1: Nutrients & Digestion • Ruminant GI • Mouth • no upper incisors, upper and lower molars • lateral chewing for shredding of forages • Saliva • relatively continuous production, more when ruminating or eating • cattle >12 g/d, sheep >2g/d • no enzymes, but sources of N(urea), P, Na • highly buffered

50. Unit 1: Nutrients & Digestion • Stomach • Reticulum (honeycomb) • esophageal opening of common to both reticulum and rumen • mucus lined walls, no enzyme secretions • moved feed to rumen, omasum • catches any foreign matter • moves feed up esophagus during regurgitation