不同RDP/RUP比例日粮对鲁西黄牛瘤胃发酵的影响

Effect of the Dietary Ratio of RDP to RUP on Ruminal Fermentation of Luxi Yellow Cattle

试验选用3头体况健康,体重350 kg左右,并安装有瘤胃瘘管的鲁西黄牛,采用3×3拉丁方试验设计,饲喂3种RDP/RUP比例分别为1.00∶1.00（A组）、1.22∶1.00（B组）、1.50∶1.00（C组）的等能等氮日粮,研究其对瘤胃内环境参数的昼夜动态变化规律的影响。结果表明：瘤胃pH受日粮RDP/RUP比值差异的影响不显著（P〉0.05）,A、B和C组pH变化范围分别为6.53~6.94、6.44~6.84和6.45~7.03。各组瘤胃pH均在饲喂后2~4 h达到最低值,随后逐渐上升;瘤胃液尿素氮以C组最高,A、B 2组差异不显著（P〉0.05）。各组瘤胃液尿素氮在08：00饲喂后2 h达到最高值,但20：00饲喂后各组变化趋势不一致。A、B 2组瘤胃液尿素氮浓度白天较低,夜晚较高,而C组正好相反;各组瘤胃液氨氮平均浓度差异不显著（P〉0.05）,动态变化趋势基本相同,均在饲喂后2 h达到最高值;瘤胃微生物蛋白（MCP）平均浓度随RDP/RUP比值升高而显著提高,C组显著高于A、B 2组（P〈0.05）。各组瘤胃液MCP浓度均在饲喂后2 h达到最低值。结果显示,以瘤胃液MCP浓度为衡量指标,日粮适宜的RDP/RUP比例为1.50∶1.00。

Three Luxi cattles fitted with ruminal fistulae were used in a 3 × 3 Latin square design to determine the effects of different ratios of ruminally degradable protein（RDP） to ruminally undegradable protein（RUP） on the ruminal internal environment parameters.The RDP/RUP were 1.00：1.00（A）,1.22：1.00（B）,1.50：1.00（C）,respectively.The results showed that ruminal pH was not affected by RDP/RUP（P〈0.05）,and the average pH was 6.53-6.94（A）,6.44-6.84（B） and 6.45-7.03（C）.The minimum value of ruminal pH was observed at 2 to 4 h after feeding,then ascended gradually;The highest ruminal urea-N concentration was observed in group C,higher than that in group A and B（P〈0.05）.Ruminal urea-N concentration of all groups peaked at 10：00,but its variation tendency was different at night.The ruminal urea-N concentration of group A and B were higher during night and lower during day,but group C was inverse;RDP/RUP didn＇t affect ruminal NH3-N concentration（P〈0.05）,and there was a peak value of ruminal NH3-N concentration at 2 h after feeding and then declined gradually.Increasing ratio of RDP/RUP increased ruminal MCP production,and ruminal MCP production of group A and B were much lower than that of group C（P〈0.05）.The production of all groups reached lowest at 2 h after feeding,and then was increased gradually.In consideration of average ruminal MCP production,the optimum dietary ratio of RDP to RUP is 1.50：1.00 in Luxi cattle.