【摘要】 研究旨在应用康奈尔绵羊净碳水化合物和蛋白质体系(Cornell sheep net carbohydrate and protein system,CNCPS-S)的预测模型预测日粮瘤胃pH值与微生物蛋白质(MCP)合成量,并通过实测验证模型预测值的准确性。选取3只安装瘤胃和十二指肠瘘管的哈萨克公羊为试验动物,配制3种精粗比为30:70、35:65、40:60的全混合日粮(TMR)。采用3×3拉丁方设计,共3期试验,每期18 d,其中10 d为预试期,8 d为样品采集,测定瘤胃液pH和MCP合成量。同时利用CNCPS-S模型预测3种日粮的MCP合成量,评价模型预测的准确性。结果表明:①3种TMR的瘤胃液pH的实测值分别在6.38～6.71、6.01～6.59、5.81～6.41之间,模型预测pH为固定值6.46;②随着精料水平增加,3种TMR均为瘤胃能氮负平衡型,瘤胃能氮平衡(RENB)值均呈下降趋势(P<0.05),3种TMR的MCP的模型预测值依次升高,分别为210.29、215.31、246.94 g/d(P>0.05),实测值也依次升高,分别为93.83、97.33、100.27 g/d(P<0.05);③经线性回归分析,3种日粮MCP的预测值与十二指肠MCP实测值之间的平均偏差比较大(平均偏差≥116 g/d),相关性低(R~2≤0.75),误差均方根(RMSE)都较高。以上结果说明,CNCPS-S对我国绵羊瘤胃pH值具有较好的预测能力,但对MCP合成量具有较低的预测能力。更多还原

【Abstract】 The purpose of this study was to predict dietary rumen pH and microbial protein(MCP)synthesis by Cornell sheep net carbohydrate and protein system(CNCPS-S) and was measured to verify the accuracy of the predicted values of the CNCPS-S model.Three Kazakh wethers with permanent ruminal and duodenal fistula were chosen and three kinds of total mixed diet(TMR) were designed of which the concentrate/roughage ratio were 30:70, 35:65 and 40:60. Using 3×3 Latin square design,each experimental period lasted for 18 d, 10 d for adaptation to the dietary treatment and 8 d for ruminal and duodenal digesta sample collections which was determined the ruminal fluid pH and MCP synthesis. Meanwhile, the CNCPS-S model was used to predict the MCP synthesis of the three TMRs to evaluate the accuracy of the model prediction. The results showed that, ①The pH values of 3 kinds of TMR were 6.38～6.71, 6.01～6.59 and 5.81～6.41, respectively, and the pH predicted by the model is a fixed value of 6.46. ②Three TMRs are all ruminal energy and nitrogen negative balance type,and ruminal energy nitrogen balance value was decreased with the increase of concentrate proportion(P<0.05). The predicted values of MCP of the three kinds of TMR were 210.29, 215.31 and 246.94 g/d respectively(P>0.05), and the measured values were 93.83, 97.33 and 100.27 g/d respectively(P<0.05). ③By linear regression analysis, the average deviation between the predicted values and the measured values of MCP of the three diets was larger(mean deviation≥ 116 g/d), the correlation was low(R~2≤0.75), and the RMSEof was higher. It is concluded that CNCPS-S had a good ability to predict the rumen pH value, but had a low ability to predict the MCP synthesis of Chinese sheep.更多还原