Effects of compound coated amino acids on milk yield,milk composition,and plasma indices in lactating yaks during warm season

LUOSANG Dunzhu; ZHANG Nan; OUJIE Ciren; SHI Jun; LIU Shilin; BASANG Wangdui; JIANG Nan

doi:10.13557/j.cnki.issn1002-2813.2025.02.004

Abstract：The experiment aimed to explore the effects of compound coated amino acids on the milk yield,milk composition,and plasma indices in lactating yaks during the warm season.Twelve Niangya yaks from Jiali County,with similar parity,calving dates,and body weight(230±30)kg,were selected and randomly divided into two groups,each with six replicates,and each replicate consisting of one lactating yak.The control group was fed through grazing and supplementary feeding,while the coated amino acids group added 15 g/(head·d)of coated methionine+50 g/(head·d)of coated lysine+30 g/(head·d)of coated choline to the supplementary feeding.The pre-test period was one week,and the formal test period was five weeks.The results showed that compared to the control group,the milk yield on day 18 and milk fat percentage on day 35 were significantly increased in the coated amino acids group(P＜0.05).The total cholesterol(TG)and glucose(GLU)concentrations on days 18 and 35 of the coated amino acids group,and the total protein(TP)and triglyceride(TC)concentrations on day 18 were significantly increased(P＜0.05),while the plasma urea nitrogen(BUN)content on day 35 was significantly decreased(P＜0.05).The total superoxide dismutase(T-SOD)activity on days 18 and 35 in the plasma of the coated amino acids group was significantly increased(P＜0.05),and the malondialdehyde(MDA)content on day 35 was significantly decreased(P＜0.05).The interleukin-2(IL-2)content in the plasma of the coated amino acids group on day 18 was significantly decreased(P＜0.05),while the immunoglobulin G(IgG)content on day 35 was significantly increased(P＜0.05).The study indicates that compound coated amino acids can improve milk yield,antioxidant capacity,and immune function in yaks during the warm season.