Study On The Energy And Protein Metabolism Rules And Requirements Of Growing Beef Cattle

Energy and protein metabolism rules and requirement factorial models of beef cattle at the age of 4⁶ and 7¹0 month were systematically studied by the feeding test, digestion-metabolism experiment, nylon bag in rumen and comparative slaughtering test.Part 1: Fifty-four healthy cross-bred(Luxi×Limousin) beef cattle were selected to study the energy and protein metabolism rules and requirement at the age of 4⁶ month. The results showed that the digestibility of DM , OM and energy were 59.68±5.46% , 64.10±7.82% and 66.60% respectively;the metabolizability of gross energy(ME/GE) and digestible energy(ME/DE) were 56.95% and 85.51%.The digestibility, deposit rate and the rumen degradable rate of protein in the diet were 72.64%, 41.43%, and 54.36%. The metabolizable energy requirements (MEm) and net energy requirements (NEm) of beef cattle were 569.50 and 398.68 KJ/kgW^0.75·d, the requirements of metabolizable energy (ME) and net energy (NE) for gain were 22400 and 11490 KJ/kg respectively.Part 2: Energy and protein metabolism rules and requirements at the age of 7¹0 month were studied with 18 healthy cross-breed(Luxi×Limousin) beef cattle.The results showed that the digestibility of DM , OM and energy were 62.55±1.65% , 65.19±1.01% and 64.12%, the metabolizability of gross energy(ME/GE) and digestible energy(ME/DE) were 54.20% and 84.53%.The diet protein digestibility , deposit rate and rumen degradable rate were 75.93%, 35.28%, and 56.28% respectively.The MEm and MEg of beef cattle were 520.87 KJ/kgW^0.75·d and 28580 KJ/kg respectively , the NEm and the NEg were 359.39KJ/kgW^0.75·d and 16940 KJ/kg.Energy and protein requirement of beef cattle can be estimated by the factorial models as follows:At the age of four to six month:DER(KJ/d)=675.40W^0.75+25710â–³W;...