This experience systematically studied energy and protein metabolism rules and requirement factorial models of growing Holstein heifer at age of 57 and 810 month by the feeding test, digestion-metabolism experiment and nylon bag in rumen test. Factorial models of growing Holstein heifer at age of 57 and 810 month were established.Experiment 1: Twenty one replacement Holstein heifers at 5-momth-old were selected to study the energy and protein metabolism rules and requirement. 21 replacement Holstein heifers were assigned into 3 groups (7 cows in per group).According to the weight and average daily gain,the diet was designed to the same crude protein(CP=16%,DM),the different DE(DE=12.85,13.25,13.66 MJ/kg,DM).The results showed that the digest-ibility of DM,OM,NDF,ADF and energy were 64.88%66.62%,67.14%69.02%,53.51%55.66%, 51.35%52.68%, 66.16%68.45%.The metabolizability of gross energy (ME/GE) and digestible energy(ME/DE) were 53.89%55.76%,81.23%81.46%. The digestibility, deposit rate and the rumen degradable rate of dietary protein were seperatelly 70.25%74.53%, 44.67%47.34%, 54.75%59.25%。Experiment 2: Twenty one growing Holstein heifer at 8-momth-old were selected to study the energy and protein metabolism rules and requirement. 21 replacement Holstein heifers were assigned into 3 groups (7 heifers in per group).According to the weight and ADG,the diet was designed to the same crude protein(CP=14%,DM),the different DE(DE=11.52,12.00,12.51 MJ/kg,DM).The results showed that the digestibility of DM, OM, NDF, ADF and energy were 59.22%60.23%, 64.67%65.51%, 58.79%61.68%, 52.23%56.60%, 61.84%63.42%.The metabolizability of gross energy (ME/GE) and digestible energy (ME/DE) were 47.99%49.96%,77.56%78.76%;The digestibility, deposit rate and the rumen degradable rate of protein in the diet were 66.20%71.48%、38.17%41.84%、47.85%49.28%.Energy and protein requirement of growing Holstein heifer were estimated by the factorial models as follows:At age of five to seven month: DER(MJ/d)=0.62546W0.75+26.25ΔW,MER(MJ/d)=0.62546W0.75+26.25ΔW,Crude protein(g/d)=5.57W0.75+512.68ΔW,Digestible crude protein of diets(g/d)=4.00W0.75+368.34ΔW,Rumen degradable protein(g/d)=3.14W0.75+288.95ΔW,Small intestine degradable protein(g/d)=3.56W0.75+327.46ΔW,Deposition protein (g/d)=2.55W0.75+235.06ΔW.At age of eight to ten month:DER(MJ/d)=0.59441W0.75+29.90ΔW,MER(MJ/d)=0.49201W0.75+21.64ΔW,Crude protein(g/d)=4.84W0.75+566.60ΔW,Digestible crude protein of diets(g/d)=3.37W0.75+394.29ΔW,Rumen degradable protein(g/d)=2.34W0.75+274.40ΔW,Small intestine degradable protein(g/d)=3.10W0.75+362.80ΔW,Deposition protein(g/d)(g/d)=1.95W0.75+228.28ΔW.Note:W,weight;ΔW,average daily gain,kg/d. |