杜寒杂交繁殖母羊氮代谢和维持净蛋白质需要的研究

Study of Nitrogen Metabolism and Net Protein Requirement for Maintenance of Dorper×Thin-tailed Han Crossbred Breeding Ewes

本试验用日粮饲喂量梯度方法研究杜寒杂交母羊不同生理时期氮的表观消化代谢规律和维持的净蛋白质需要。15只同期发情和人工授精妊娠母羊按体重分为3组:1)自由采食组,2)80%自由采食组,3)60%自由采食组;另有9只空怀母羊做对照。消化代谢试验分别在空怀期,妊娠期40、100和130d,哺乳期20、50和80d进行,得到母羊不同时期的氮表观代谢和维持净蛋白质需要参数。氮的表观消化率在空怀期,妊娠40、100、130d及哺乳20、50、80d时分别为45.21%~51.34%;59.71%~64.14%、69.98%~71.91%、67.34%~68.80%;73.72%~82.71%、72.79%~80.51%、73.57%~76.47%。在空怀期和哺乳中、后期存在显著差异(P【0.01);空怀期、妊娠40、100、130d及哺乳20、50、80d时母羊氮采食量(N intake,g·kg-1 W0.75·d-1)和氮沉积量(RN,g·kg-1W0.75·d-1)之间的回归方程分别为RN=0.341 5NI-0.269 7;RN=0.489 5NI-0.303 7、RN=0.384 5NI-0.323 4、RN=0.457 4NI-0.496 2;RN=0.252 1NI-0.338 0、RN=0.282 1NI-0.313 6、RN=0.286 3NI-0.2982(P【0.01)。母羊空怀期、妊娠40、100、130d及哺乳20、50、80d7个阶段的维持净氮需要分别为269.7、303.7、323.4、496.2、338.0、313.6和298.2mg·kg-1 W0.75·d-1。

This experiment was conducted to investigate the nitrogen apparent digestibility of different feeding levels and net protein requirement for maintenance of Dorper× Thin-tailed Han crossbred ewes in different physiological periods.According to the weight,fifteen ewes with synchronous estrus and artificial insemination were assigned into three groups,one group fed ad libitum(100%),and the other two groups fed eighty percents(80%)or sixty percents(60%)of ad libitum,and another nine non-pregnant ewes were assigned into blank control group.Digestibility trials was performed in the non-pregnant condition and 40th,100th,130th day of pregnancy and20th,50th,80th day of lactation,to determine the metabolic parameters of nitrogen and net protein requirement for maintenance.The apparent digestibilities of nitrogen in the non-pregnancy and 40th,100th,130th day of pregnancy and 20th,50th,80th day of lactation were 45.21%-51.34%;59.71%-64.14%,69.98%-71.91%,67.34%-68.80%;73.72%-82.71%,72.79%-80.51%,73.57%-76.47%,respectively,which only in the non-pregnancy,mid-and late-lactation had significant differences(P<0.01).The regression equations between nitrogen intake(N intake,g·kg-1 W0.75·d-1)and nitrogen retention(RN,g·kg-1 W0.75·d-1)in the non-pregnancy and 40th,100th,130th day of pregnancy and 20th,50th,80th day of lactation were RN=0.341 5NI-0.269 7;RN=0.489 5NI-0.303 7,RN=0.384 5NI-0.323 4,RN=0.457 4NI-0.496 2;RN=0.252 1NI-0.338 0,RN=0.282 1NI-0.313 6,RN=0.286 3NI-0.298 2(P<0.01),respectively.The net nitrogen requirements for maintenance of ewes in the non-pregnancy and 40th,100th,130th day of pregnancy and 20th,50th,80th day of lactation were 269.7,303.7,323.4,496.2,338.0,313.6and 298.2mg·kg-1 W0.75·d-1,respectively.