Maternal Supplementation With Rumen‐Protected Methionine and Trace Minerals During Lactation Improves Growth Performance and Increases the Abundance of Fiber‐Degrading Bacteria in Yak Calves

ABSTRACT

This study was conducted to investigate the effects of trace minerals (TM) and rumen‐protected methionine (RPM) maternal supplementation on growth performance and rumen bacteria in yak calves. Six 3‐month‐old yak calves (bodyweight: 38.5 ± 3 kg) were selected from each maternal diet group (control [CON], TM, and RPM group) and named as follows: CON‐YC (CON group yak calves), TM‐YC (TM group yak calves), and RPM‐YC (RPM group yak calves). Yaks in the RPM group showed greater milk protein and omega‐6 polyunsaturated fatty acid contents than those in the CON group ( p  = 0.01). The TM‐YC and RPM‐YC groups showed higher ( p  = 0.04) average daily gain (ADG) and a lower ( p  < 0.01) incidence of diarrhea than the CON‐YC. Concentrations of propionate and butyrate in the rumen were higher in the RPM‐YC group than in the CON‐YC and TM‐YC groups ( p  < 0.05). Rumen bacteria composition analysis revealed that the abundance of Firmicutes was augmented in the RPM‐YC group, with a greater relative abundance of Ruminococcaceae_NK4A214_group than the CON‐YC group ( p  < 0.05). These results indicate that supplementation of lactating yaks with TM and RPM increased ADG and fiber‐degrading bacteria abundance in calves while decreasing the incidence of diarrhea.