基于CNCPS6.5的泌乳早期奶牛乳真蛋白质产量对可代谢蛋氨酸供应量的Meta分析

Meta-analysis of milk true protein yield responses to metabolizable methionine supply in early stage of Holstein cows based on CNCPS6.5 model

中文关键词: 蛋氨酸  代谢蛋白质  乳真蛋白质产量  奶牛  meta分析

英文关键词: Methionine, Metabolizable  protein, milk  true protein  yield, lactating  cows, meta-analysis.

中文摘要:

      本文在对泌乳早期荷斯坦奶牛真蛋白质产量(MTPY)的影响因素进行主成分分析的基础上,运用SAS的非线性混合模型(NLMIXED),分别以代谢蛋白质中蛋氨酸百分含量(Met%MP)、可代谢蛋氨酸供给量(mMETs)和可代谢蛋氨酸供应量与ME进食量的比值(mMETs/ME)作为自变量,与MTPY的剂量效应关系进行了Logistic参数拟合。结果表明,以mMETs作为自变量拟合的Logistic模型效果最优。MTPY预测值经残差校正后(MTPY校正),再与mMETs进行混合模型(MIXED)回归分析,得到预测回归方程MTPY校正 = (951.03±38.2) + (3.05±0.67)×mMETs(R²=0.1912, RMSE=143.2)。补饲RP-Met产品的边际效率会随补饲量的增加而降低,并非恒定不变的。试验设计类型为交叉设计时,对试验的固定效应可能会造成干扰,原因可能与交叉设计的试验期过短有关。

英文摘要:

      A meta-analysis using a logistic regression model fitted using nonlinear mixed model procedures was performed on milk true protein yield (MTPY) responses from 20 published studies on early stage of lactating dairy cows with Met%MP, mMETs and mMETs/ME ratio as independent variable, respectively. Results indicated that the logistic model fitting effect with mMETs being the independent variable was the best. The model prediction of MTPY adjusted by residual regressed with mMETs with MIXED procedure of SAS, and the regression equation was obtained (MTPYadjusted = (951.03±38.2) + (3.05±0.67)×mMETs, R²=0.1912, RMSE=143.2). The marginal efficiency of mMETs use for milk true protein synthesis decreased as the supply of metabolizable methionine increased. Additionally, there was a confounded interactive effect between crossover design with metabolizable methionine supplementation, which was probably owing to a relatively short experimental period of crossover design.