A Comprehensive Review of Rumen-Protected Methionine Supplementation in Dairy Cows: Effects on Lactation Performance, Amino Acid Metabolism, and Reproductive Outcomes

Methionine is recognized as one of the most limiting amino acids for lactating dairy cows, particularly in diets based on corn and soybean meal. However, free methionine is extensively degraded by ruminal microorganisms, necessitating the use of rumen-protected methionine (RPM) formulations to ensure post-ruminal delivery. This comprehensive review synthesizes findings from multiple studies investigating the effects of RPM supplementation on milk production, milk composition, amino acid metabolism, and reproductive performance in dairy cows. The evidence consistently demonstrates that RPM supplementation increases milk protein concentration and yield, with meta-analysis confirming significant improvements in milk fat and protein percentages. Optimal RPM dosage ranges from ۷.۵ to ۱۲.۵ g per cow daily, achieving a metabolizable protein lysine-to-methionine ratio of approximately ۲.۸:۱. Plasma methionine concentrations are reliably elevated by RPM feeding, with peak concentrations observed ۹-۱۲ hours post-feeding. Importantly, RPM supplementation has been shown to reduce pregnancy loss in multiparous cows and enhance embryonic development, although effects on overall pregnancy rates remain inconsistent. At the molecular level, RPM influences mammalian target of rapamycin signaling, reduces oxidative stress markers, and modulates protein turnover in skeletal muscle. This review provides evidence-based recommendations for RPM inclusion in dairy rations and identifies critical knowledge gaps requiring further investigation

کلیدواژه ها:

rumen-protected methionine ، dairy cows ، milk protein ، amino acid metabolism ، reproductive performance