Studies On The Energy And Protein Requirements In Female Lambs Of Mutton Sheep At20-35kg

The study selected hornless Dorset and Thin-Tailed Han crossbred F2which fixedathwart cross. The whole experiment was divided into the feeding test，digestion-metabolism experiment and comparative slaughtering test. Energy and protein metabolismrules and requirement at the growth of20-35kg were studied by this experiment.Thenutrition requirement resolved to maintenance and growth. Energy and protein requirementfactoria models of mutton sheep at the growth of20-35kg were studied.Forty-two hornlessDorset and Thin-Tailed Han crossbred F2which fixed athwart cross was selected,thirtylambs were used for slaughtering test and twelve lambs were used for digestion-metabolism experiment.Six lambs were randomly chosen and slaughtered at the beginningof the trial for measuring the initial body composition.The remaining24lambs wereoffered a pelleted mixture diet for ad libitum intake(12),70%ad libitum intake(6),40%adlibitum intake(6).When the12lambs fed ad libitum reached28kg,six of the lambs wererandomly chosen and slaughtered.The remaining18lambs were fed a pelleted mixture dietand divided into3intake levels. When the lambs in ad libitum treatment group reached at35kg BW, the lambs were all slaughtered.Twelve lambs (28kg) were divided into threegroups in the digestion-metabolism experiment,the feed and the intake level were the sameas slaughter experiment.In the digestion-metabolism experiment,total collection of fecesand urine was conducted.The results showed that:1.The maintenance requirements of hornless Dorset and Thin-Tailed Han crossbredF2which fixed athwart cross. for NEm and MEm were226.4248KJ/kg and332.531KJ/kg metabolic BW (BW0.75), respectively, with a partial efficiency of energy utilizationfor maintenance being0.68. Net energy and metabolic energy requirements for growthranged from0.94to4.51MJ·d-1and2.27to10.85MJ·d-1, respectively, for the lambs from20to35kg body weight gaining100to350g·d-1. The partial efficiency of ME forgrowth was0.416. The maintenance requirements for Net Protein was429.798mg N/kg或2.69g CP/kg metabolic BW (BW0.75).The lambs from20to35kg body weight therequirements of net protein for growth was17.37-62.73g/kg of EBW.2.The net energy requirement,metabolizable energy requirement and net proteinrequirement of hornless Dorset and Thin-Tailed Han crossbred F2which fixed athwartcross at20-35kg can be estimated by the factorial models as follows: The net energy requirement, NER=NEm+NEg, as followsNER=226.4248KJ/kgBW0.75·d+NEglog10energy, MJ=0.219+1.496log10EBW, kgEBW（kg）=-2.541+0.95×BW（kg）The metabolizable energy requirement MER=MEm+MEg：MER=332.531KJ/kgBW0.75·d+NEg/0.416log10energy, MJ=0.219+1.496log10EBW, kgEBW（kg）=-2.541+0.95×BW（kg）The net protein requirement NpR=Npm+Npg,as followsNpR=2.69g/kgW0.75.d+NpgLog10(NR)=2.18+1.05Log10(EBW)EBW（kg）=-2.541+0.95×BW（kg）...