11/23/20141Determination of Nutrient Requirements and Availability Part IV: Endogenous loss, Energy, Balance Trials.11/23/2014211/23/20143Determination of Energy ValuesGross Energy is typically determined by calorimetry (needed for DE, ME and NE) Can be predicted from equation:GE = 4,143+ (56 x %EE) + (15 x % CP) – (44 x % Ash)Determination of Energy ValuesDigestible energy= gross energy – fecal energyValues are typically apparent DE. (does not separate endogenous from feed origin)Can be predicted from equation:DE = 4,168 – (9.1 x % Ash) + (1.9 x % CP) – (3.6 X NDF) orDE = 1,161 + (0.749 x GE) – (4.3 x ash) – (4.1 x NDF)11/23/20144Determination of Energy ValuesMetabolizable energy = Digestible energy – urinary (gas)Gas loss in non-ruminants is typically low (< 0.5% of GE) and ignored.Can be predicted from the proximate analysis or in relation to the DE. ME is typically 92-98% of DE.Determination of Energy ValuesNet Energy = Metabolizable Energy - Heat Increment NE can be determined by comparative slaughter or indirect calorimetry.Prediction equation: NE = (0.700 x DE) + (1.61 x EE)+ (0.48 x Starch)- (0.91 x CP)- (0.83 x ADF)Balance Trials• Feed diet (with or without marker)• Collect feces and urine• Determine digestibility (nutrient consumed – nutrient excreted = absorbed• Nutrient content of urine • Retention = absorbed – urinary loss.11/23/20145Comparison of Digestibility with Marker vs Total Collection• Adaptation period: 3 days• Collection period: 4 days• Feed intake (4 days) = 1662.6 g• Total Fecal output = 484.3 g• Total Urine output = 6562 mL• Nitrogen and phosphorus in feed, feces and urine• Titanium in feed and fecesNitrogen and Phosphorus BalanceFeed intake, gFecal output, gDMdigestibility, %1662.6240.685.5NitrogenIntake, gFecal nitrogen, gNitrogen absorbed, gNitrogen digestibility, %57.910.247.782.4Urinary Nitrogen, gNitrogen retention, gNitrogen retention, % of absorbed16.930.864.6Phosphorus intake, gFecal Phosphorus, gPhosphorus absorbed, gPhosphorus digestibilty, %9.715.294.4245.5Urinary phosphorus,gPhosphorus retention, gPhosphorus retentin, % of absorbed0.044.3899.1Digestibility Calculation, %Total MarkerNitrogen82.4 80.7Phosphorus45.5 41.0Titanium RecoveryIntake, mgFecal recovery,mg1286123696.1%Nutrient Balance in 25 lb pigsFeed Intake: TotalProteinNitrogenPhosphorous552 g/d120.2 g/d19.2 g/d3.29 g/dFeces: WetDry NitrogenPhosphorous160.5 g/d84.3 g/d3.38 g/d1.77 g/dUrine: VolumeNitrogenPhosphorous2178 ml/d5.67 g/d13.8 mg/dAll pigs fed a corn /soybean meal diet with 20.5% Crude protein, 1.20% lysine and 0.58% total Phosphorus. Total collection and marker used.11/23/20146Phosphorous Balance• Each day pigs consumed 3.29 g of phosphorous.• Of this, 56.4% (1.77 g) was excreted in the feces and 43.6% was absorbed (1.51 g).• Urinary loss was 0.48% of intake (14 mg, 0.014 g).• Therefore, 98.9% (1.51g) of the P absorbed was retained. • The greatest impact on P can be made at the level of digestibility in the diet.Nitrogen Balance• Each day, pigs consumed 120 g (1/4 lb) of protein or 19.2 g of nitrogen.• Of this, 18.6% (3.38 g N) was excreted in the feces and 81.4% (15.8 g N) was absorbed.• Urinary loss was 30.4% of intake or 37.1% of absorbed.• Only 62.9 % of the nitrogen absorbed was retained. • Therefore, there is potential to improve nitrogen balance by:• Improving digestibility of protein in the diet • Improving retention of the absorbed amino acids.11/23/20147Summary• Endogenous losses of a nutrient can be estimated using either:• Regression analysis and extrapolation back to zero• Feeding an nutrient-free diet• Energy values are determined by calorimetry in combination with feeding trials• Balance trials can be used to determine the retention of a nutrient in the body. Typically done in metabolism crates with collection of feces and