| The aim of this study is to investigate the energy requirement of Suffolk×Altay crossed ewes and provide the theoretical basis for feeding standard and the scientific basis for efficient feeding. Forty-five Suffolk×Altay crossed ewes, weaned at2.5months with mean weight about19kg, were selected to this study. The diet was made according to granulationg TMR base on reconmmendation of nutrient requirements of sheep(NRC,2007). Energy requirement factorial models of crossbred ewes at20-35kg and the distributing rules of the energy in body were systematically studied by the feeding test, the digestion-metabolism experiment and the comparative slaughtering test. The results showed that:1. The apparent digestibility of dry matter of crossbred ewes were68.28±2.24%, the apparent digestibility of gross energy were69.17±2.45%, the metabolizability of gross energy were55.82±1.26%, the metabolizability of digestible energy were80.72±1.12%.2. Net and metabolizable energy requirements for maintenance were0.2788MJ/kg W0075·d and0.3596MJ/kgW0.75·d respectively. Efficiency of metabolizable energy for maintenance was0.78. Net energy requirements for growth of20and35kg ewes at an ADG of250g were3.38M/d and4.68MJ/d, respectively. Metabolizable energy efficiency for gain was0.44.3. The energy requirement of sheep can be estimated by the factorial models as follows:3.1The net energy requirement can be estimated by the factorial models as follows: NE=0.2788MJ/kgW0.75·d+NEg Lg(BEC, MJ)=0.3529+1.4821Lg(EBW, Kg) EBW(kg)=-4.7131+1.0504SBW(kg)3.2The metabolizable energy requirement can be estimated by the faetorial models as follows: ME=0.3596MJ/kgW0.75-d+NEg/0.44Lg(BEC, MJ)=0.3529+1.4821Lg(EBW, Kg) EBW (kg)=-4.7131+1.0504SBW (kg)4. The proportion of retained energy in blood, head and hoof, muscle, bone, carcass fat, visceral fat, viscera, digestive tract, skin and wool accounting for reteained energy in body were1.39%,3.24%,20.48%,5.35%,36.41%,14.90%,2.29%,2.71%,9.32%and3.91%, respectively. |
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