Effect of protected Methionine and Lysine on Milk yield and Composition in Holstein Dairy Cow under Different Dietary Crude Protein Levels :Meta-analysis
2016
Choi, N.J., Chonbuk National University, Jeonju, Republic of Korea
The present study was conducted to investigate effect of dietary protected amino acid on milk yield and composition in dairy cow using meta-analysis. Total 21 research papers were employed in analysis, and mixed model was used for the analysis of effects. Effect of protected methionine (PM) and combination of protected methionine and lysine (PML) were investigated under two different levels of dietary crude protein (CP, less than 18% and greater than 18%). For performance of dairy cow, milk yield, milk composition including milk fat and protein content and yield and 4% FCM (fat corrected milk) production were used for analysis. In case of milk yield, a trend of increment was found at PM supplementation at low CP (P=0.055). However, the effect of PM at high CP was detected as not significant (P greater than 0.05). In case of milk protein, inclusion of PM at low CP showed significant decrement (P less than 0.05). However, there was no significant effect of MP on milk protein at high CP (P greater than 0.05). Supplementation of MP at high CP level showed significant increment of milk fat (P less than 0.05). MP supplementation represented significant increment of 4% FCM production (P less than 0.05) regardless of dietary CP levels. Effects of PML on milk yield and composition at both of low and high dietary CP were not significant in this study. However, it seem to be that there was a possible positive effect of MPL application at high dietary CP on performance of dairy cow.
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