Animal Science 320, Week 1 Notes
Animal Science 320, Week 1 Notes AN S 320
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This 7 page Class Notes was uploaded by Danielle Garrison on Monday August 8, 2016. The Class Notes belongs to AN S 320 at Iowa State University taught by Morris in Fall 2016. Since its upload, it has received 38 views. For similar materials see Animal Feeds and Feeding in Animal Science at Iowa State University.
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Date Created: 08/08/16
Chapter 1 – Review from 319 Types of digestion: all 4 occur in all species, just in different spots and at different amounts o Mechanical o Chemical o Enzymatic – in stomach due to HCl (acetic) o Fermentation – where microbes lives drives what we feed them Ruminants – occurs in rumen Monogastrics - “1 stomach” Parts of digestive tract - Monogastrics o Mouth Types of digestion – primarily mechanical; some enzymatic Functions – eating; begins digestion (mechanical and enzymatic) Palatability and taste (umami, sweet, sour, bitter, salt) o T1R2 – sweet (NOT in cats or birds) Hummingbirds – T1R1/T1R3 (umami); responds to amino acids, mutation in hummingbirds, doesn’t respond to amino acids o Taste is important in regards to what we feed them Secretes saliva o Composition – water, mucin, bicarbonate salts, enzymes (some species) o Other functions – lubrication, buffer, nutrition from rumen microbes, prevents rumen frothing (bicarbonate comes in play here), and protects mouth membranes o Stomach Types of digestion – mechanical, enzymatic, and chemical Secretions – HCl, Protease (Pepsinogen – Pepsin), hormones (gastrin – stimulates motility; HCl and pepsinogen release) Functions – store food; acidic (pH 2) – kills bacteria, activate enzymes and denatures proteins; pepsinogen – initiates protein digestion (needs HCl); mucous secretion (lubricate); rennin or chymosin – enzyme in young ruminants o Small Intestine Types of digestion – mechanical and enzymatic Secretions INTO duodenum 1. Pancreas o Proteases (breakdown proteins) – Trypsin, Chymotrypsin, Carboxypeptidase o Carbohydrase – Amylase (-ase = enzyme) o Lipase 2. Liver – “Brain” for the digestive tract o Bile (emulsifies fat) 3. Intestinal mucosa o Carbohydrase’s (Maltase, etc.) o Proteases o Gut hormones Absorption of nutrients – Jejunum and Ileum Secretions Entering SI Bile – enters SI o Synthesized by liver, stored in gallbladder (NOT horses or llamas) o Under hormonal control (CCK) o Emulsifies fat o 98% recycled back to liver Pancreatic juice o Synthesized by pancreas o Digestive enzymes (trypsinogen, chymotrypsinogen, amylase, lipase, procarboxypeptidase) o Bicarbonate Duodenal wall secretions o Brush border enzymes – sucrase, maltase, lactase, aminopeptidase, dipeptidases No sucrase in ruminants No lactase in birds, amphibians, or reptiles Gastrointestinal hormones Ghrelin – from stomach and pancreas o Stimulates hunger o Leptin – “satiety;” secreted from fat cells; says when to stop eating Gastrin – from stomach (when food present there) o Stimulates production of HCl and pepsinogen, and motility Secretin – from SI when chyme and acid present o Stimulates pancreatic for buffering o Decreases stomach motility and acid CCK (Cholecystokinin) – from SI when fat & protein present o Stimulates pancreatic and bile secretions o Decreases stomach acid GIP (gastric inhibitory peptide) – from SI when fat & glucose present o Stimulates insulin secretion & inhibits stomach motility & secretions o LI – Hind Gut Fermentation Sections (3) Cecum – very pronounced in rabbits and horses o Size varies among species Colon and rectum Horses and rabbits – can NOT survive without appendix Functions Types of digestions – mechanical and fermentation Mineral absorption Bacterial fermentation of fiber o Synthesize some water soluble vitamins – B and K o Breakdown fiber o Produce and absorb VFAs (acetate, propionate, butyrate) To know from this lecture: o 4 types digestion o Types of digestion that are occurring at each major section of GI tract o Primary functions of each section of GI tract Avian and Ruminant Digestive Systems – Chapter 1 continued Differences b/w avian & other monogastrics o Mouth – no teeth; no amylase (chickens) o Esophagus – crop (feed storage) o Proventriculus – stomach (HCl and pepsin); rapid passage rate o Gizzard (Ventriculus) – grinds feed o SI – NO lactase o LI – ceca o Cloaca – feces mixed with urinary waste here Functions of ruminant digestive tract o Mouth – same as Monogastric (mechanical digestion; taste) Secretion of salvia No enzymes Secretion of buffers – sodium bicarbonate, sodium phosphate Recycling – N, Na, P, H2O o “Rumen” – stomach (4 compartments) Reticulum, rumen, and omasum Fermentation o Synthesis of water soluble vitamins and vitamin K o Synthesis of BCP o Breakdown fiber o Produce VFAs Absorb fermentation end products Abomasum – similar to Monogastric stomach Secrete HCl and pepsinogen o SI – similar to monogastrics; NO sucrase o LI – similar to monogastrics Carbohydrate Digestion – Ruminants o High forage diets – increased acetate o High grain diets – increased propionate Protein digestion – ruminants o Must consider protein needs in – bacteria in rumen; animal Lipid Digestion – Ruminants o Ability to saturate and elongate fats in rumen Chapter 1, Review 2: Objectives: o Know how nutrients are classified (6 categories) o Components of Proximate Analysis o Calculate as feed and dry matter of nutrients Major Nutrient Classes: o Water – makes up ~70% of animal body weight Sources Drinking it In feed (“moisture”) o Forages: 5 (dried hay) to 90% (pasture) o Grains: 8 to 30% o Silages: 30 to 50% o Dry kibble (pet feed): 10 to 12% Losses: urine, feces, sweat, vaporization from lungs, production (eggs, milk) o Protein o Fat o Carbohydrates o Vitamins o Minerals o To formulate any animal diet – have to know nutrients in feed ingredients Feed analysis systems: o Proximate (Weende system) – standard system (used across species) Developed in 1864 at Weende Experiment Station, Germany Uses water, protein, fat, total mineral (ash), and some carbs Components: DM, Ash, CP, EE (fat), crude fiber (CF), NFE NFE determined by calculation o Detergent (Van Soest system) Developed 1964 at USDA Beltsville Research Center Used for herbivores due to only using fiber components As-fed vs Dry Matter (DM) o As-fed: water/moisture + all nutrients o DM: nutrients only; all water is removed DM % = wt after drying/wt before drying x 100 % water/moisture = 100 – DM % % DM = 100 – moisture % Problems with DM: Measured by heating sample in an oven between 55-105 degrees C o Left in until no change in wgt (1-5 days) Drying with heat, destroys some nutrients o Vitamins, AAs o Other methods Freeze drying – meats, pet foods, high protein feeds Toluene Distillation – silage and forage o Dried at lower temps for a longer period Significance: Variations among feeds Other nutrients are present within DM – affects the expression of concentrations of nutrients in feeds o Example: End wt: 550 g Beg wt: 750 g % DM? (550/750) x 100 = 73.33% % Moisture? 100- 73.33 = 26.67% Summary of Review 2 o All feeds contain some moisture o 100 – moisture = % DM o Nutrients concentrated when water is taken out o Wgt of sample is less when water is out o Components of proximate analysis: DM/OM, EE, CP, CF, NFE Chapter 1 – Review of Digestive Processes, Dry Matter, and Unit Conversions Post – Lecture Material 4 digestive processes – mechanical, chemical, enzymatic, fermentative o Fermentation – relies on lg populations of microbes living in digestive tract to ferment fibers If occurs too rapidly – acid produced and creates unfavorable environment for microbes Knowledge Checks: o 4 major digestive process types – mechanical, chemical, enzymatic, fermentative o Fermentative digestion begin in cow – Rumen o Fermentative digestion begin in dog – Large Intestine o Chemical digestion begin in chicken – Stomach o Enzymatic digestion begin in human – Mouth o Rabbit appendix called – cecum Horse or rabbit would die without their appendix o Digestive tracts of guinea pig, hamster, rabbit, koala, and rock hyrax are related in the fact that they are all what types of fermentation – hind gut fermentation Nutrient classification o 6 major nutrient classes – water, proteins, fats, carbohydrates, vitamins, minerals o Knowledge checks: Calcium – Mineral Iron – Mineral Dietary fiber - Carbohydrate Starch – Carbohydrate Sucrose - Carbohydrate Linoleic acid – Fatty acid Linolenic acid – Fatty acid Lysine – Amino acid Methionine – Amino acid Ascorbic acid - Vitamin Thiamin – Vitamin Dry Matter and Moisture Examples o Bucket of feed out to feed your horse. Does feed in your bucket contain some moisture? Yes o Keepers at the zoo feed a leopard a raw meat diet. Does raw meat diet contain some moisture? Yes o Neighbor’s sheep are out grazing. Does grass contain moisture? Yes o Unit conversions: 1 lb = 0.454 kg 1 kg = 2.2 lb 1 kg = 1,000 g 1 g = 1,000 mg 1 lb = 16 oz 1 ton = 2,000 lb 1 bushel of corn = 56 lb