应用CNCPS-S模型预测全混合日粮碳水化合物绵羊瘤胃降解率的研究

本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）的瘤胃降解预测模型预测日粮碳水化合物（CHO）瘤胃有效降解率,并实测验证CNCPS-S模型预测值的准确性。选取3只安装瘤胃瘘管、体重分别为（38.03±1.56）kg的哈萨克公羊作为试验动物,配制3种精粗比分别为30：70、35：65、40：60的全混合日粮（TMR）,利用瘤胃灌注试验和尼龙袋试验实测3种日粮CHO的瘤胃外流速度（Kp）和降解率,同时利用CNCPS-S模型预测3种日粮CHO的Kp与降解率,对CHO的降解率预测值和实测值进行线性回归分析,评价模型预测的准确性。结果表明：3种TMR的瘤胃食糜Kp随精料比例增加而依次升高（P<0.01）,分别为3.58%/h、3.83%/h、4.05%/h,据此计算而得的CHO的降解率分别为42.7%、43.1%、42.3%（P>0.05）;随精料比例的增加,3种TMR的瘤胃食糜Kp的模型预测值依次升高（P>0.05）,分别为1.62%/h、1.63%/h、1.64%/h,CHO瘤胃降解率的预测值分别为39.5%、39.1%、39.6%（P>0.05）;3种日粮CHO瘤胃降解率的预测值与实测值之间的平均偏差比较小（≤ 4 g/100 g CHO）,相关性较高（R² ≥ 0.86）,均方根误差也较低（RMSE ≤ 1.93 g/100 g CHO）。以上结果说明,CNCPS-S瘤胃降解预测模型对日粮CHO的降解率具有较好的预测能力。

Prediction of Ruminal Degradability of Total Mixed Ration Carbohydrate in Sheep by CNCPS-S Model

The purpose of this study was to predict the ruminal effective degradability (ED) of dietary carbohydrate (CHO) 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 (38.03±1.56) kg body weight and permanent ruminal 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,respectively.The outflow rate (Kp) of ruminal digesta and ruminal ED of three kinds of dietary CHO were measured by the ruminal perfusion test and nylon bag test.Meanwhile,the CNCPS-S model was used to predict Kp of ruminal digesta and ED of CHO in three TMRs,and the predicted and measured values of ED of CHO were analyzed by linear regression analysis so as to evaluate the accuracy of the model prediction.The results showed that:The Kp of ruminal digesta of three kinds of TMR increased sequentially with the proportion of concentrate (P<0.01),which were 3.58%/h,3.83%/h and 4.05%/h,respectively.And the ruminal ED of dietary CHO based on these calculations were 42.7%,43.1% and 42.3% (P>0.05),respectively.The model predictive values of ruminal digesta Kp in three TMRs were increased with the increase of concentrate proportion,which were 1.62,1.63 and 1.64%/h (P>0.05),respectively.The predicted values of ruminal ED of dietary CHO were 39.5%,39.1% and 39.6% (P>0.05),respectively.The average deviation between the predicted and measured values of ruminal ED of three dietary CHO was relatively small (mean deviation ≤ 4 g/100 g CHO),and the correlation was high (R² ≥ 0.86),the root mean square error was also lower (RMSE ≤ 1.93 g/100 g CHO).It was concluded that the prediction model of ruminal degradation in CNCPS-S had a good predictive ability for the ruminal effective degradability of dietary CHO.