The aim of this experiment was to investigate the effects of different roughage source diets on growth performance and immune organs development of weaned yak calves.Twenty-one Datong yak calves(male)with similar genetic background,days of age(about 45 days of age)and body weight[(36.47±0.99)kg]were selected and randomly divided into 3 groups with 7 yak calves in each group.The alfalfa hay group(AT group)group was fed milk replacer and starter supplemented with alfalfa hay,the oat hay group(OT group)was fed milk replacer and starter supplemented with oat hay,and the alfalfa hay and oat hay group(AOT group)was fed milk replacer and starter supplemented with alfalfa hay+oat hay(alfalfa hay∶oat hay=1∶1).The pre-experimental period lasted for 21 days,and the experimental period lasted for 120 days.The results showed as follows:1)compared with AT and OT groups,the final body weight of AOT group was signifi-cantly increased(P＜0.05),and the feed to gain ratio was significantly decreased(P＜0.05).2)Compared with AT and OT groups,the AOT group had a clear boundary between red medulla and white medulla in spleen,and a larger radius of white medulla;and the contents of tuftsin,interferon-β and tumor necrosis fac-tor-α in spleen were significantly increased(P＜0.05).3)Compared with AT and OT groups,the AOT group had a larger cortical area in thymus;and the contents of thymosin β-4,prothymosin α,thymosin,immuno-globulin G and interleukin-1 β in thymus were significantly increased(P＜0.05).In summary,compared with single feeding of alfalfa hay or oat hay,the mixed feeding of alfalfa hay and oat hay is more conducive to im-prove the feed conversion rate and promoting the growth and development of weaned yak calves.Meanwhile,the mixed feeding of alfalfa hay and oat hay can promote the development of spleen and thymus organs and im-prove the immune function of weaned yak calves.[Chinese Journal of Animal Nutrition,2024,36(5):3106-3116]
维普
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