Animal Science 320, Week 4 Notes
Animal Science 320, Week 4 Notes AN S 320
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This 6 page Class Notes was uploaded by Danielle Garrison on Saturday September 17, 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 20 views. For similar materials see Animal Feeds and Feeding in Animal Science at Iowa State University.
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Date Created: 09/17/16
Energy Systems (Ch. 6) Objectives: o Calculate TDN Explain strengths and limitations o Explain energy partitioning system and its uses Calculate various components of this system Define GE, DE, ME, and NE Feed industry – different systems: o Total Digestible Nutrients (TDN) – horses and sheep o Partitioning of Feedstuff Energy Digestible Energy (DE) Metabolizable Energy (ME) - calories Net Energy (NE) – production species use this type TDN – traditional, used to express DE concentration of feeds o Basis are physiological fuel values based on digestibility (at water values) Carbohydrates – 4.0 Fat – 9.0; 2.25x more energy Protein – 4.0 o Determining: 1. Calculate NFE 2. Conduct digestibility trial and determine digestibility, % of: CP, CF, NFE, and EE 3. Calculate concentration of each digestible nutrient – using all DMB of diet Digestible Protein (DP) = CP x CP digestibility % Digestible fiber (DCF) = CF x digestibility % Digestible NFE (DNFE) = NFE x digestibility % Digestible EE (DEE) = EE x digestilbity % x 2.25 4. Calculate TDN TDN = %DP + %DCF + %DNFE + %DEE Expressed as % of ration or in units of weight (lb) NOT EXPRESSED IN ENERGY UNITS (KCAL) o Example: Protein: 20.5% x 0.76 = 15.58% Fiber: 15.5% x 0.75 = 11.63% NFE (digestible carbs) = 42.0% x 0.83 = 34.86% EE (fat) = 4.0% x 0.55 x 2.25 = 4.95% TDN = 15.58 + 11.63 + 34.86 + 4.95 = 67.02% (or lb) o Limitations: Digestibility trials Errors in chemical analyses (CF) Errors in sample collections Any factors that affect digestibility will impact TDN Does NOT include all energy losses in metabolism Does NOT include urine loss or methane gas loss (heat) Does NOT include: added altogether = heat increment (HI) Work of digestion, heat of fermentation, heat of nutrient metabolism Overestimates energy value of some feeds – forages Underestimates energy value of some feeds – concentrates/grains Not helpful in measuring animal performance Partitioning of Feedstuff Energy o Gross Energy (GE): total potential energy of feed Measured by bomb calorimeter Fats > proteins > carbohydrates 9.45 > 5.65 > 4.10 Kcal/gram Water, ash, vitamins – NO ENERGY Doesn’t differentiate availability of energy – little correlation b/w GE and usefulness to animal o Digestible Energy (DE): not used to express energy req of poultry or reptiles (urine and feces mixed together when excreted) GE – fecal losses Fecal losses Ruminants > Monogastrics Ruminants – ~60% with low quality forage diets o Metabolizable Energy (ME): used for most species ME = DE – (Gas + Urinary Energy) Calculated in neutral growth animal o Zero nitrogen balance o Protein stored or lost from muscle with distort values Urine (urea) ~5% of GE o Lost as result of protein metabolism o Ruminants > Monogastrics Combustible gases o Ruminants >>> Monogastrics Mostly lost as CH4 ~3-10% of GE Monogastrics losses small and generally ignored 0.0-3.0% of DE Net Energy (NE) – Ruminants Amount of energy that’s COMPLETELY useful to animal for maintenance, lactation, growth NE = ME – HI o HI: increase in heat lost because of energy costs of digestion and metabolic processes Digestion, fermentation, nutrient metabolism Management – contributes to thermal regulation in cold climate (feed hay) Contributes to heat load in warm climate (feed corn) Work of digestion o Activity, chewing, GI contractions 30% of total heat lost in animals (ruminants) Low quality forage increases work of digestion Movement and excitement for meal Heat of fermentation: o Heat released by microbes during fermentation 5-10% of GE Low quality forage increases heat of fermentation Increase in lipids decreases heat of fermentation Heat of nutrient metabolism: o 10-30% of GE lost Energy Systems – Ruminant Nutrition o NE standard for cattle – more accurate o Used to predict daily gain o Used to predict feed costs o Values NEm – net energy maintenance Requirement: o Maintenance req (zero gain or loss of energy from body tissues) Basal metabolic activities and body temp regulation o Varies with weight, breed, age, sex, season, temp, nutritional status, physiological status Larger framed cattle LESS energy for gain compared to small frame cattle due to muscle being more efficient for growth than fat o Have to calculate amount of feed necessary for maintenance 1 st Determination: o Calorimetry – animal placed in animal calorimeter o Comparative slaughter Whole body carcass energy over time periods NE, Mcal/Kg = retained energy (carcass) and DM intake – linear relationship NEm = NEl values NEg – net energy gain Lover value than NEm NE used less efficiently for gain than maintenance NEl – net energy lactation NE used as efficiently for lactation and maintenance o NE requirements for dairy cows, expressed with 1 value – NEl Considers o Amount of milk produced o Fat percentage of milk produced Summary: o 2 major energy systems – TDN and Energy Partitioning o TDN – basic estimate for DE but has some limitations for predicting performance o Reducing NEm will allow more energy from feed to be used for productive purposes o NEg less efficient than NEm Feedstuffs (Chapter 7) Classes of Energy Concentrates: o Grains - Corn, milk, oats, barley, wheat, rye, triticale o Fats and Oils (TDN) Fats – 2.25x more energy than concentrates or proteins Cows and horses can NOT tolerate a lot of fat in their diets o Byproducts of sugar or baking industries Energy Concentrates – General Properties Nutrient Grains Fats and Oils Sugar or Food By- Product Energy High Very High High Crude Fiber (CF) Low Low Low Protein: Negligible Negligible Negligible Quantity Low Very Low Very Low Quality Low Low Low Deficient: Lysine, Tryptophane Excess: Leucine Rumen Low N/A N/A Degradability Energy Concentrates – Mineral Considerations Nutrient Grains Fats and Oils Sugar and Food By-Products Calcium Low Low Low Phospohorus N/A N/A N/A Quantity Higher than Low Low forages Availability Low in Low in N/A monogastrics monogastrics High in ruminants High in ruminants Salt Low Low Low (unless food waste) Energy Concentrates – Vitamin Considerations Nutrient Grains Fats and Oils Sugar or Food By- Products Vitamin A Low (except corn) Low Low (Carotene) Vitamin D Low Low Low Vitamin E Fair Fair Low Thiamin (B vit) High Low Low Niacin (B vit) High (low Low Low availability for monogastrics) Riboflavin, Low Low Low Pantothenic acid, Vit B12, Biotin Grains – structure o Bran: fiber (hemicellulose), outer part; contains majority of fiber o Endosperm: inner part of kernel Starch: 98% in kernel Gluten: 75% protein in kernel o Germ Oil: 81% in kernel; higher in unsaturated fatty acids Protein: 23% in kernel Digetible Carbohydrates: o Starch (glucose storage) Storage of energy in plants Seeds, tubers, roots, and fruits o Amylose – straight chain polymer; alpha 1-4 links of glucose o Amylopectin – branched chain polymer; alpha 1-4 and alpha 1-6 links branched More digestible than amylose Like stacked pieces of paper Properties of grains o Corn – 56 lb/bushel High energy (88% TDN, DM basis) Low fiber (NDF, 10% DM; highly digestible) Low protein (8-10% DM) Low Lysine and Tryptophan High Leucine Low Ca (0.03%) Moderate P (0.30%) (Ca:P ratio 2:1) 50% of P bound to Phytate (70-80% in corn) Vitamins: High in beta-carotene, thiamin, niacin (unavailable to monogastrics) Low in other B vitamins Use of corn – livestock diets o Swine and Poultry Supplemental nutrients needed – AAs, available P, Ca, Salt, Trace minerals, Fat soluble vitamins, B vitamins o Ruminants and Horses Limited by fiber requirements Fiber requirement met by forages Supplemental nutrients needed – Crude Protein (CP), P, Ca, Salt, Trace Minerals, Fat soluble vitamins Variations – corn composition o Genetic variants High lysine (opaque-2) Reduced amount of protein needed in Monogastric diets Limitations: lower yields; soft kernels (subject to ear rot) Waxy corn 100% amylopectin Improved starch digestibility Variable improvements in animal performance High Amylose Corn >50% Amylose; high fructose corn syrup High Oil Corn 7-8% oil; may improve feed efficiency and rate of gain Low Phytate Corn Increased digestibility of P in corn; reduced amount of supplemental P needed; reduced P excretion Ground Ear Corn Also known as Corn or Cob Meal Contains 20% cob; 70 lbs/bushel; 87% TDN, DM basis; 28% NDF Uses: not used in swine or poultry o Can be used for ruminants or horses If used, reduce amount of forage in diet
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