ANSC 318 1st Edition Lecture 7 Outline of Last Lecture I Chemical Evaluation of Feed Stuffs and Feed Digestibility Outline of Current Lecture II Review Total Digestible Nutrient Comparisons III Feed Energy a Gross Energy b Digestible Energy c Metabolized Energy d Net Energy and Heat Increment IV Whole Animal Calorimetry a Comparative Slaughter Balance Current Lecture know this TDN and Net Energy Systems Comparison of TDN and Net Energy NE Systems Feed Lb of TDN per Mcal of NE Mcal of NE lb of feed per lb of feed per lb of TDN Corn Grain Good quality Hay Poor quality Hay NE per unit TDN 0 83 0 50 1 0 0 5 1 2 1 0 More Intermediate CH4 HI losses per unit TDN Less Intermediate 0 42 0 3 0 7 Less More 2 fold 3 fold Mcal of NE per lb of TDN Mcal of NE per lb of feed lb of TDN per lb of feed Feed Energy not a nutrient it is a property of nutrients nutrients that supply energy CHO lipids and proteins animals use feed energy for chemical and mechanical work synthesis of enzymes and hormones maintenance of homeothermy These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute synthesis of animal products Energy 1 aspect of a feed s supply of determine its feed value cannot be determined converted to heat and measured in Calories heat nutrition energy helps greatly Gross Energy Digestible chemically can only be measured to raise 1 g of water by 1 C Fecal Energy Losses Energy Metabolized Energy Urine and Gas Energy Losses Net Energy Heat Increment Losses Gross Income inaccurate Net Energy accurate always smallest cal g Horse rations use DE Pig rations use ME Most ruminant rations use NE Gross Energy GE potential energy of a feed aka heat of combustion provides no information on the availability of a feed s potential energy very little difference in GE feed values ex Hay vs corn CHO fat and heat are all around equal but provide very different NE values use a bomb calorimeter to determine heat of combustion Digestible Energy DE DE GE fecal energy FE FE contains energy from undigested feed and metabolic fecal material microbes similar to TDN doesn t account for losses in urine heat or gas overestimates roughage underestimates grain Ranges of Fecal Loss Pigs 3 20 of GE usually 10 Horses 10 40 of GE High grain diet ruminants 10 30 of GE High roughage diet ruminants 40 60 of GE Metabolized Energy ME ME DE urine energy UE gaseous energy GPD UE energy lost in urine due to incomplete oxidation of nitrogenous compounds i e urea GPD energy lost as combustible gases during fermentation usually methane greenhouse gasses ME more accurate than DE in predicting feed s true energy value Ranges in Urine Losses small Pigs 2 3 of GE Ruminants 3 4 of GE Ranges in Methane Losses Pigs 1 2 of GE High grain diet ruminants 4 6 of GE High roughage diet ruminants 6 12 of GE Methane reflects 25 times more infrared light than CO 2 1 gas in global warming decreasing methane increased feed efficiency ionophores monensin are a feed additive that alters microbe populations affecting acid production and causes an animal s methane losses to decrease Net Energy NE NE ME heat increment HI portion of GE that is actually useful to the body directly available to animal for metabolic functions most accurate estimate of feed value Heat Increment HI I Heat Digestion Fermentation a Actions of digestive enzymes within GIT b Movement of digesta through GIT c Absorption of nutrients through GIT lumen bloodstream d Actions of microbial fermentation in GIT II Heat of Nutrient Metabolism heat associated with the metabolic processes of product formation synthesis of protein lactose and lipids III Heat Increment heat of digestion fermentation and nutrient metabolism a Shows inefficient use of ME for maintenance and production b Only useful during cold stress Types of NE I NEm used to maintain body tissue II NEg used to deposit lead and adipose tissue III NEl used to produce milk IV Nep used for fetal growth and development Methods of Measuring NE Value I Whole Animal Calorimetry used in 1989 to establish NE feed values for dairy cows II Comparative Slaughter Balance used in 1984 to establish NE feed values for beef cattle Whole Animal Calorimetry based on the principal that heat is generated during oxidation of organic compounds to CO 2 and H2O heat generated by an animal during metabolism of feed nutrients is determined by measuring how much O2 is consumed and how much CO2 is produced HP kcal 3 89 x O2 1 2 x CO2 52 x CH4 DO NOT need to know the equation just the concept have both air tight machines and face mask machines Steps of Whole Animal Calorimetry I Train Animals to the Chambers II Adapt them to test diet III Place animal in air tight chamber IV Measure total O2 consumption and CO2 CH4 production calculate exact O2 going in Measuring NE Value of a Feed remember NE ME HI rearrange ME NE HI Growing animals ME NEg tissue energy NEm heat HI heat Growing animals ME tissue energy heat there are 2 sources of heat NEm and HI Comparative Animal Slaughter Balance I Group of uniform steers selected II Initial group slaughtered and body energy determined III Remaining steers are assigned to test diets and fed for a number of days IV Final group is slaughtered and body energy is determined V Change in body energy between first and last group reflects NE feed values