抗菌肽对犊牛生长性能、腹泻率、抗氧化指标和免疫指标的影响OA

The aim of this experiment was to investigate the effects of different doses of antimicrobial pep-tides on growth performance,diarrhea rate,antioxidant index,immune index and fecal flora of calves.Sixty healthy newborn Holstein calves with similar body weights[(35.0±4.1)kg]were selected and randomly divided into 4 groups,with 15 calves in each group.The control group was fed a basic diet,and the other three groups were added with 50 mg/kg(low dose group),100 mg/kg(medium dose group)and 150 mg/kg(high dose group)of antimicrobial peptides in the basic diet,respectively.The pre-trial period was 10 days and the positive trial period was 50 d.The results showed that:① calves in the medium and high-dose groups had significantly higher average daily gain(ADG)than the control group(P<0.05),increased by 15.61%and 13.58%,respectively,and the feed-to-weight ratio was significantly reduced(P<0.05);② the diarrhea rate of each antimicrobial peptide group was significantly lower than that of the control group(P<0.05),and the diarrhea rate of the middle-dose group was the lowest,which was 44.44%lower than that of the control group;③the activities of serum superoxide dismutase(SOD)and glutathione peroxidase(GSH-Px)in the middle and high dose antimicrobial peptide groups were significantly increased(P<0.05),and the content of malondialdehyde(MDA)was significantly reduced(P<0.05);immunoglobulin A(IgA)and immunoglobulin G(IgG)in the middle and high immunoglobulin M(IgM)and interferon-γ(IFN-γ)were significantly increased(P<0.05);④ the medium and high doses of antimicrobial peptides could significantly reduce the number of harmful bacteria such as Escherichia coli(P<0.05),increase the abundance of beneficial bacteria such as Bifidobacterium and Lactobacillus(P<0.05),and optimize the intestinal microecological structure.In conclusion,adding an appropriate amount of antimicrobial peptides to the calf diet can effectively improve growth performance,reduce diarrhea rate,enhance antioxidant and immune function,regulate the intestinal microbiota,and promote calf health,with the best effect observed at an addition level of 100 mg/kg.