LAUSR

Abstract The objectives of this study were to investigate the effects of supplementing rumen-protected methionine (RPM) or lysine (RPL) alone or in combination with RPM and RPL (RPML) on milk yield and milk components, rumen fermentation characteristics, and the rumen microbiome in lactating yaks. Thirty-two multiparous lactating yaks with parity (2.13 ± 1.08 lactations), body weight (169 ± 15.0 kg), and milk yield (1.02 ± 0.13 kg/d) were blocked by milk yield and randomly assigned into one of the four treatments: control (CON; basal diet without adding rumen-protected amino acid) and the basal diet supplemented with RPM (50.0 g/d), RPL (66.7 g/d), or RPML (12.5 g/d RPM and 50.0 g/d RPL). The basal diet consisted of 600 g/kg rye hay and 400 g/kg corn-based concentrate. The dry matter intake, lactoferrin concentration, and lactose yield were greater (P