Energy And Protein Requirements For Pregnancy And Lactation On Meat Sheep

The purpose of this study is to investigate the energy and protein requirements of Suffolk×Altay crossed ewes during pregnancy and lactation periods and provide the theoretical basis for feeding standard and the scientific basis for efficient feeding. Fifteen healthy ewes were choosed for estrus synchronization and artificial insemination, and then randomly divided into three treatment groups after pregnancy tests(ad libitum group, 80% the ad libitum intake group and 60% the ad libitum intake group), Digestion and metabolism trial and gas metabolism trial were sdudied in the periods of the non-pregnancy, 60 th and 100 th days of pregnancy, 20 th and 50 th days of lactation, The energy and protein requirement parameters were obtained by the carbon and nitrogen balance method.The results showed that:1.The apparent digestibilities of dry matter and organic matter of ewes increased significantly with decreasing level of feed intake(P<0.05). The apparent digestibilities of dry matter, organic matter, neutral detergent fiber, acid detergent fiber and energy during pregnancy and lactation is significantly higher than the non-pregnant(P<0.05).2.The linear relationship between digestible protein(DP) requirements and body weight gain(BWG) of crossbred ewes in the non-pregnant period and on the 60 th, 100 th days of pregnancy were estimated as follows. Non-pregnant period: DP(g/d)=1.130 BWG(g/d)+218.0(R2=0.8793,RMSE=27.896,n=12,P <0.0001), On 60 th day of pregnancy: DP(g/d)=0.3983 BWG(g/d)+113.9(R2=0.8836,RMSE=13.958,n=15,P <0.0001), On100 th day of pregnancy: DP(g/d)=0.4657 BWG(g/d)+85.33(R2=0.8660,RMSE=19.529,n=12,P <0.0001).3. The protein requirements for maintenance(Pm) of crossbred ewes in the non-pregnant period, pregnancy and lactation were 3.569, 2.594~4.263 and 3.419~ 4.581g/mg W0.75·d, respectively.4.The metabolizable energy requirements for maintenance of crossbred ewes in the non-pregnant period, pregnancy and lactation were 292.72, 259.83, 307.03, 363.54 and 371.40 k J/kg W0.75·d, respectively. The net energy requirements for maintenance of crossbred ewes in the non-pregnant period, pregnancy and lactation were 132.98,58.94~173.58 and 67.51~114.16 k J/kg W0.75·d, respectively.