Research On The Mechanism Of Nutrients Utilization And The Requirements Of Energy And Protein In Alpine Merino Lambs

The study was conducted to investigate the metabolic mechanism and requirements of energy and protein of Alpine Merino lambs.Those experiments were used as feeding,digestion-metabolism,and comparative slaughter trial.And more,total fifty-eight Alpine Merino male lambs and female lambs were donor with similar date of birth,body weight and 3 months weaned age.In other words,forty lambs were used in the comparative slaughter trial and eighteen lambs were used in the digestion-metabolism trial.The results showed that:1.At different feeding levels,the daily gain of male lambs in the free feeding group was 213.58 g·d^-1 and the feed weight ratio was 7.22;The daily gain of female lambs in the free feeding group was 123.25 g·d^-1,and the feed weight ratio was 9.40.Average daily gain and feed efficiency of male lambs were higher than female lambs（P<0.05）.With the up-grading of feed level,the daily gains were increased but the feed-to-weight ratios were decreased.The effects of gender,feeding level and their interaction on daily gain and the ratio of lambs were significant（P<0.01）.The apparent digestibility of DM,OM,CP,NDF and ADF in ad libitum group of male lambs were 56.18%,60.44%,58.03%,23.17%and 18.43%,the apparent digestibility of DM,OM,CP,NDF and ADF in ad libitum group of female lambs was 60.08%,64.46%,56.31%,39.06%and 27.34%.The apparent digestibility of DM,NDF,ADF,OM in female ad libitum group was significantly higher than that in male（P<0.05）.The apparent digestibility of DM and OM in 40%feeding level group were significantly higher than the other two groups（P<0.05）.The feeding level had a significant effect on rumen pH and NH₃-N concentration（P<0.05）.Rumen VFA concentration of male lambs were higher than female lambs（P<0.05）.The 70%feeding level group had the higher concentrations of acetic acid,propionate acid,butyrate acid and TVFA than that in the other two groups（P<0.05）.2.The slaughter rate,carcass net muscle percentage,and meat to bone ratio of male lambs were 44.29%,28.18%and 2.67,the those indexes of female lambs were45.98%,27.06%and 2.53.The effect of feeding level on slaughter rate was not significant（P>0.05）.The shrunk body weight,fasting weight,carcass weight,net meat weight and bone weight of lambs were increased with the up-grading of feed level（P<0.05）.At the ad libitum group,the visceral fat and gastrointestinal tract fat of male lambs were 356.67g and 1693.33g,and those of female lambs were 623.33g and2056.67g.The proportion of visceral fat and gastrointestinal tract fat in male lambs was lower than that in female lambs（P<0.01）.There was interaction between gender and feeding level on visceral fat and its proportion（P<0.05）.With the increase of feeding level,the weight of internal organs were increased significantly（P<0.01）.There was interaction between gender and feeding level on liver weight and liver proportion（P<0.05）.The feeding level had a significant effect on the weight of each gastric tissue（P<0.01）.There was not significant effect on the energy and protein content in wool at different feeding levels（P>0.05）.The protein content of male lamb bone were decreased with the decrease of feeding level（P<0.05）.The energy contents of lamb body also were decreased with the decrease of feeding level（P<0.05）.The protein content of male lamb body was higher than that of female lamb（P<0.05）.3.The maintenance requirements of NE and ME for Alpine Merino male lambs were 240.44KJ·kg^-1EBW^0.75·d^-1 and 306.45KJ·kg^-1EBW^0.75·d^-1,the efficiency of ME utilization for maintenance were 0.74.The female lambs maintenance requirements for NE and ME were 215.68KJ·kg^-1EBW^0.75·d^-11 and 279.32KJ·kg^-1EBW^0.75·d^-1,the efficiency of ME utilization for maintenance were 0.71.The partial efficiency of ME utilization for growth were 0.40.The prediction models of total net energy,metabolizable energy and digestible energy requirements of Alpine Merino male lambs are as follows:（1）NE=NE_m+NE_g,NE_m=240.44 KJ·kg^-1EBW^0.75·d^-1,EBW,kg=-4.3782+（0.9218×BW,kg）,NE_g=?GE_EBW,Log₁₀ GE_EBW,MJ=1.0578×Log₁₀（EBW,kg）+0.9521;（2）ME=ME_m+ME_g,ME_m=306.45KJ·kg^-1EBW^0.75·d^-1,ME_g=NE_g/0.40;（3）DE=ME/0.84.The prediction models of total net energy,metabolizable energy and digestible energy requirements of Alpine Merino female lambs are as follows:（1）NE=NE_m+NE_g,NE_m=215.68KJ·kg^-1EBW^0.75·d^-1;EBW,kg=-3.3007+（0.9223×BW,kg）,NE_g=?GE_EBW,Log₁₀ GE_EBW,MJ=1.4184×Log₁₀（EBW,kg）+0.4367;（2）ME=ME_m+ME_g,ME_m=279.32KJ·kg^-1EBW^0.75·d^-1,ME=NE_g/0.40;（3）DE=ME/0.82.4.The daily requirement of maintaining net protein was 0.98g·kg^-1EBW^0.75 for Alpine Merino male lambs and 1.38 g·kg^-1EBW^0.75 for female lambs.The prediction models of total net protein,digestible protein and crude protein daily requirement of Alpine Merino male lambs are as follows:（1）NP=NP_m+NP_g,NP_m=0.98 g·kg^-1EBW^0.75;NP_g=?NPR_EBW,Log₁₀（NPR）=0.8497×Log₁₀（EBW,kg）-0.5107;EBW,kg=-4.3782+（0.9218×BW,kg）;（2）DCP=NP/0.47;（3）CP=DCP/0.58.The prediction models of total net protein,digestible protein and crude protein requirement of Alpine Merino female lambs are as follows:（1）NP=NP_m+NP_g,NP_m=1.38 g·kg^-1EBW^0.75;NP_g=?NPR_EBW,Log₁₀（NPR）=0.7576×Log₁₀（EBW,kg）-0.4210;EBW,kg=-3.3007+（0.9223×BW,kg）;（2）DCP=NP/0.32;（3）CP=DCP/0.56.