NRC energy evaluation system Eastridge, M.L. 2002. Energy in the New Dairy NRC. Department of Animal Sciences, The Ohio State t University, it pp. 7. NRC. 2001. Nutrient requirements of dairy cattle. Seventh revised edition. National Academy Press, Washington DC, USA, pp. 13-27. Feedstuff NE l content calculation 5 steps : STEP 1 * truly digestible crude protein * truly digestible fatty acids * truly digestible neutral detergent fibre ADICP = acid detergent insoluble CP
- FA = EE 1 & 100 % digestibility -FA = EE 1 & 100 % digestibility = 075* 0.75 (NDFn ADL) * [ 1 (ADL/NDFn) 0.667 ] NDFn = NDF NDICP (neutral detergent insoluble CP) - FA = EE 1 & 100 % digestibility =075* 0.75 (NDFn ADL) * [ 1 (ADL/NDFn) 0.667 ] NDFn = NDF - NDICP = 0.98 00 [(NDF-NDICP)+CP+EE+CA] ]* PAF * truly digestible ibl nonfiber carbohydrates (NFC) = 0.98 00 [(NDF-NDICP)+CP+EE+CA] ]* PAF Effect of processing on NFC digestibility processing adjustment factor
Feedstuff NE l content calculation 5 steps : STEP 1 - Summative approach Average FA content t metabolic faecal TDN Feedstuff NE l content calculation 5 steps : - Corrections different individual equations * Animal protein meals (different equation) (no non- structural carbohydrates, but NDIresidue) TDN 1X (%) = CP digest * CP + FA * 2,25 + 0,98 * (100-CP-Ash-EE) - 7 * Fat supplements (10% glycerol + 90% fatty acids) TDN 1X (%) = 0,1 * EE + FA digest * EE * 0,9 * 2,25 Feedstuff NE l content calculation 5 steps : STEP 2 Estimating digestible energy at maintenance (DE 1X, Mcal/kg DM) - multiplying py digestible nutrient concentrations by respective heats of combustion * carbohydrates: 4.2 Mcal/kg * protein: 5.6 Mcal/kg * long chain fatty acids: 9.4 Mcal/kg * glycerol: gy 4.3 Mcal/kg * correction metabolic faecal energy = 0.07 x 4.4 Mcal/kg Feedstuff NE l content calculation 5 steps : STEP 3 Estimating digestible energy at actual intake (DE 3 or 4X, Mcal/kg DM) - highly digestible diets at maintenance: greater depression rate TDN1X (%) 62 67 72 77 % digestibility 1.5 1.8 3.8 4.7
Feedstuff NE l content calculation 5 steps : STEP 4 Estimating metabolisable energy from digestible energy at actual intake (ME 3 or 4X, Mcal/kg DM) - Empirical formula - Correction for higher EE levels (DE = ME) Feedstuff NE l content calculation 5 steps : STEP 5 Estimating NE l from ME at actual intake (NE l 3 or 4X, Mcal/kg DM) -Empirical formula - Correction for higher EE levels (NE = 0.8 ME) Estimating NE M from ME at actual intake (NE M 3 or 4X, Mcal/kg DM) - Empirical formula Energy supply and requirements 1. Supply energy content t of feed 2. Requirements energy requirements of animal based on needs for maintenance & production (e.g. meat, milk production, labour, ) 1. Maintenance - 0.080080 Mcal NE /kgw 0.75 M (+ 10% activity allowance compared to former edition) - Adjustment for breed 3. Units same for supply and requirements (MJ)
2. Lactation - Energy contained in the milk produced = Σ heats of combustion of individual milk components (fat, protein, lactose) - Heats of combustion (Mcal/kg): fat (9.29), protein* (5.47), lactose (3.95) 3. Pregnancy - Importance during dry period - k = 0.64 4. Activity & environmental effects 5. Tissue mobilisation and repletion