利用体外模拟瘤胃发酵技术预测奶牛生产性能的研究

本试验旨在利用全混合日粮（TMR）体外发酵参数预测奶牛的生产性能，采集2头体重550 kg、安装永久瘤胃瘘管的健康荷斯坦奶牛瘤胃液，并取40种不同的TMR进行体外发酵试验，测定体外发酵24 h的乙酸、丙酸、丁酸、氨态氮（NH₃-N）含量，以及甲烷（CH₄）排放量、微生物蛋白质（MCP）、体外干物质消失率（IVDMD）、体外蛋白质消失率（IVCPD）和体外有机物消失率（IVOMD）等指标。记录饲喂不同TMR的奶牛对应的生产性能（产奶量、乳蛋白率、乳脂率），并与奶牛生产性能之间建立预测模型。结果显示：①产奶量与丙酸含量（r=0.37，P<0.05）、MCP（r=0.40，P<0.05）均呈显著正相关，但与IVCPD（r=-0.44，P<0.01）呈极显著负相关；乳脂率与乙酸含量（r=0.55，P<0.01）、甲烷排放量（r=0.36，P<0.05）、MCP（r=0.40，P<0.05）呈极显著或显著正相关；乳蛋白率与MCP（r=0.91，P<0.01）、IVDMD（r=0.44，P<0.01）、IVCPD（r=0.45，P<0.01）呈极显著正相关，但是与IVOMD（r=-0.56，P<0.01）呈极显著负相关。②奶牛的生产性能可用体外发酵参数作为预测因子进行预测。产奶量（kg/d）=29.72-0.86IVCPD（R²=0.73，RSD²=47.26，P<0.001）；乳脂率（%）=0.40+0.06AA（R²=0.91，RSD²=0.15，P<0.001）；乳蛋白率（%）=1.52+0.06MCP（R²=0.78，RSD²=0.01，P<0.001）。奶牛的生产性能预测值与实际值的误差在允许的范围内，表明预测方程是可行的。

Prediction of Dairy Cow Production Performance by in vitro Fermentation Technology

The object of this experiment was to predict the production performance of dairy cows by in vitro fermentation parameters of total mixed ration (TMR).The rumen fluid that was collected from two Holstein dairy cows with 550 kg body weight and permanent fistula,and 40 kinds of TMR were collected and used in the in vitro fermentation experiment,the contents of acetic acid,propionic acid,butyric acid, NH₃-N,CH₄,MCP,IVDMD,IVCPD and IVOMD of fermented liquid were determined when fermented for 24 h.The production performance of dairy cows fed TMR was recorded (milk yield,milk fat rate and milk protein rate),and the prediction model was established between them and the production performance of dairy cows.The results showed as follows:①Milk production and propionic acid content (r=0.37,P<0.05),MCP (r=0.40,P<0.05) were significantly positively correlated.However,it was extremely significantly negatively correlated with the IVCPD (r=-0.44,P<0.01).There was a significantly or extremely significantly positive correlation between milk fat rate and acetic acid content (r=0.55,P<0.01),CH₄ emission(r=0.36,P<0.05),MCP(r=0.40,P<0.05).There was an extremely significantly positive correlation between milk protein rate and MCP (r=0.91,P<0.01),IVDMD (r=0.44,P<0.01),IVCPD (r=0.45,P<0.01).However,it was extremely negatively correlated with the IVOMD (r=-0.56,P<0.01).②The production performance of Holstein dairy cows could be predicted using in vitro fermentation parameters.Milk production (kg/d)=29.72-0.86IVCPD (R²=0.73,RSD²=47.26,P<0.001).Milk fat rate (%)=0.40+0.06AA (R²=0.91,RSD²=0.15,P<0.001).Milk protein rate (%)=1.52+0.06MCP (R²=0.78,RSD²=0.01,P<0.001).The results showed the error between the predicted value and the actual value of production performance was within the allowable range,indicating that the equations were feasible.