【摘要】 以3头利木赞×鲁西黄牛杂交一代公牛为研究对象,应用永久性瘤胃瘘管和颈静脉插管技术,研究了不同非蛋白氮(NPN)、硫水平对肉牛营养物质代谢、铜的生物学利用率和需要量的影响。试验根据3个日粮尿素和硫水平(0%和0.150%,1%和0.225%,2%和0.300%)分3个阶段进行,每个阶段设3个日粮铜水平(10,25和50mg/kg),采用拉丁方试验设计。研究结果表明:日粮NPN和硫水平一定时,增加铜水平,能提高血铜浓度、血清铜蓝蛋白和SOD活力,减少瘤胃微生物蛋白质合成(P<0.05);日粮铜水平一定时,提高NPN和硫水平,可使血清铜蓝蛋白和SOD活力下降,血铜浓度降低,微生物蛋白质合成增加(P<0.05)。日粮中尿素和硫水平分别为0%和0.150%、1%和0.225%、2%和0.300%时,肉牛铜的需要量相应为10、10和25 mg/kg日粮铜。更多还原

【Abstract】 Crossbred(Limousin × Lu-xi) beef cattles,fitted with permanent cannulas in the rumen,and catheter into jugular vein,were used in the study.The experiments were divided into three stages according to three dietary levels of NPN and sulfur(0% and 0.150%,1% and 0.225%,2% and 0.300%),each level corresponded with three concentrations of copper that were 10,25 and 50 mg/kg in the diets,and were conducted in Latin square designs to access the effects of dietary NPN and sulfur on metabolism of nutrients,the bioavailability and the requirement of copper in beef cattles.The results indicated that plasma copper concentration and activities of Cp or SOD increased(P<0.05),but the synthesis of ruminal MCP reduced with increasing dietary copper in the same level of NPN and sulfur in the diets.In the presence of high dietary NPN and S concentration,the bioavailability of dietary copper declined,but the synthesis of ruminal MCP increased(P< 0.05).It was suggested that the optimal requirements of copper were 10,10 and 25 mg/kg for cattles fed diets containing urea and sulfur 0% and 0.150%,1% and 0.225%,2% and 0.300% respectively.更多还原