北京地区不同泌乳水平中国荷斯坦奶牛乳成分模型建立及相关性分析

Establishment and Correlation Analysis of Milk Composition Model of Chinese Holstein Cows with Different Lactation Levels in Beijing Area

为探索北京地区不同泌乳水平中国荷斯坦奶牛泌乳量和乳成分特征,本研究应用曲线回归分析方法构建泌乳量及乳成分变化规律模型。以2016—2019年北京地区中国荷斯坦奶牛的阿菲金在线乳成分分析仪记录的数据为基础,构建泌乳量和乳成分随泌乳天数变化的模型,分析不同泌乳水平中国荷斯坦奶牛的乳成分-泌乳天数曲线的差异性以及泌乳量和电导率与各乳成分之间的相关关系。结果表明:不同泌乳水平的中国荷斯坦奶牛在乳成分和泌乳量上均存在极显著差异(P<0.01)。对各曲线模型进行对比分析发现,三次方模型能较好地拟合北京地区不同泌乳水平中国荷斯坦奶牛各乳成分-泌乳天数曲线。不同泌乳阶段的高、低产奶牛的乳糖率、乳脂率、乳蛋白率和脂蛋比与泌乳量及电导率均具有显著或极显著相关性(P<0.05或P<0.01)。由此可知,泌乳量和电导率是引起乳成分改变的重要因素,因此,对不同泌乳水平的奶牛分别拟合分析具有一定的实践指导意义。

In order to explore the characteristics of lactation yield and milk composition of Chinese Holstein dairy cows with different lactation levels in Beijing area,this study applied a curve regression analysis method to build models of lactation yield and milk composition changes.Based on the data recorded by Affitin’s online milk composition analyzer for Chinese Holstein cows in Beijing area from 2016 to 2019,the models of changes in lactation yield and milk composition with lactation days were built,and the difference in milk compositionlactation time curve and the correlation between lactation yield and electrical conductivity and each milk composition of Chinese Holstein cows with different levels of lactation were analyzed.The results showed that Chinese Holstein cows with different lactation levels had extremely significant differences in milk composition and lactation yield(P<0.01).A comparative analysis of each curve model showed that the cubic model could well fit the milk composition-lactation days curves of Chinese Holstein cows with different lactation levels in Beijing area.The lactose rate,milk fat rate,milk protein rate and lipoprotein ratio of high and low-yielding cows at different lactation stages had significant or extremely significant correlations with lactation yield and electrical conductivity(P<0.05 or P<0.01).It can be seen that lactation yield and electrical conductivity are important factors that cause changes in milk composition.Therefore,it is of practical significance to fit and analyze dairy cows with different lactation levels.