Starter feed enhances growth, antioxidant capacity, and gut microbiota in Chawula yak calves.

Yak has ability to adapt the harsh environments like extremely cold, anoxic, strong ultraviolet rays and shortage of pasture. It is observed that the nutritional supply during the preweaning period is highly associated with the development of the gastrointestinal tract and immunity of animals. In this study, twenty-one male yak calves were divided into control group (DFC), starter feed group 1 (DFO), and starter feed group 2 (DFT) to study the growth of early weaning Chawula yak calves. Calves in group DFC were free-ranged, DFO group were fed with alfalfa (1.4 kg/head/day) and starter feed 1 (1.4 kg/head/day), and DFT group were fed with alfalfa ( 1.4 kg/head/day) and starter feed 2 ( 1.4 kg/head/day) for 6 weeks. The body weight of yak calves in DFT was significantly higher than that of control yaks in DFC (P < 0.05), and the net weight growth rate in DFO (P < 0.001) and DFT (P < 0.0001) were both obviously higher than that in the DFC group. The chest girth (bust) in group DFO (P < 0.05) and DFT (P < 0.05) were both markedly higher than that in the DFC group. The serum contents of T-AOC in DFC calves were markedly lower than DFO (P < 0.01) and DFT (P < 0.001) yaks. Also, T-AOC was obviously higher in DFT yaks than in DFO animals (P < 0.05). The levels of GSH-Px were significantly higher in DFO (P < 0.01) and DFT (P < 0.01) yaks than DFC yaks. High throughout sequencing achieved 391520, 356907 and 353763 filtered sequences in DFC, DFO and DFT yaks, and one phylum (Firmicutes B 370539) and thirty-seven genera (Phocaeicola A 858004, Cryptobacteroides, Evtepia, CAG-273, etc.) were identified as biomarkers in yak calves. We observed that starter feeds could promote the growth of early weaning Chawula yak calves by enhancing antioxidant capacity and regulating the gut microbiota.