枯草芽孢杆菌对脂多糖应激肉仔鸡生长性能、免疫性能和血清抗氧化性能的影响

Effects of Bacillus subtilis on Growth Performance,Immune Performance and Serum Antioxidant Performance of Broilers Challenged with Lipopolysaccharide

本试验旨在研究枯草芽孢杆菌(BS)对脂多糖(LPS)应激肉仔鸡生长性能、免疫性能和血清抗氧化性能的影响。选用1日龄健康爱拔益加(AA)肉仔鸡192只(公母各占1/2),采用2×2两因子试验设计,2个因子分别为饲粮(饲喂基础饲粮或添加200 g/t BS的试验饲粮)和LPS应激(口腔灌服LPS溶液或生理盐水),随机分为:1)基础饲粮+生理盐水组;2)基础饲粮+LPS组;3)试验饲粮+生理盐水组;4)试验饲粮+LPS组,共计4个组,每组6个重复,每个重复8只鸡,试验期为28 d,分为3个阶段,包括应激前期(第1~14天)、LPS应激期(第15~21天)、恢复期(第22~28天)。结果表明:1)在第1~14天,饲粮中添加BS可显著提高肉仔鸡平均日增重(ADG)(P<0.05)。LPS应激显著降低第15~21天、第22~28天ADG(P<0.05),而饲粮中添加BS的肉仔鸡ADG显著高于未添加BS的肉仔鸡(P<0.05)。在第22~28天,饲粮中添加BS可显著降低饲料转化率(FCR)(P<0.05)。2)在第21和28天,LPS应激条件下,LPS应激显著提高脾脏指数(P<0.05),饲粮中添加BS可显著降低第28天脾脏指数(P<0.05)。在整个试验期,饲粮中添加BS与LPS应激对胸腺指数和法氏囊指数无显著影响(P>0.05)。3)在第21天,在LPS应激条件下,LPS应激显著提高血清中免疫球蛋白G(IgG)的含量(P<0.05),饲粮中添加BS可显著降低血清免疫球蛋白A(IgA)的含量(P<0.05)。在第28天,各试验处理对血清免疫球蛋白含量无显著影响(P>0.05)。4)在第21天,与基础饲粮组相比,饲粮中添加BS对血清白细胞介素(IL)-1β、IL-6、肿瘤坏死因子-α(TNF-α)的含量无显著影响(P>0.05)。LPS应激显著提高血清IL-1β、IL-6的含量(P<0.05)。在LPS应激条件下,饲粮中添加BS可显著降低血清IL-10、TNF-α的含量(P<0.05)。在第28天,在LPS应激条件下,饲粮中添加BS可显著降低血清皮质酮(CORT)、IL-1β含量(P<0.05)。与无应激相比,LPS应激显著增加了血清IL-6、TNF-α的含量(P<0.05),对血清IL-10含量无显著影响(P>0.05)。5)在第21天,在LPS应激条件下,饲粮中添加BS可显著提高血清总抗氧化能力(T-AOC)(P<0.05),显著降低血清丙二醛(MDA)含量(P<0.05),显著增加血清过氧化氢酶(CAT)活性(P<0.05),对血清超氧化物歧化酶(SOD)活性无显著影响(P>0.05)。在第28天,LPS应激显著降低血清SOD活性(P<0.05),对血清T-AOC、MDA含量和CAT活性无显著影响(P>0.05)。综上所述,饲粮中添加BS可以缓解免疫应激造成的肉仔鸡生长性能降低,改善血清抗氧化性能,抑制血清炎性细胞因子含量的增加,进而增强机体免疫力,从而减轻LPS应激对动物机体造成的损伤。

This experiment was aimed to investigate the effects of Bacillus subtilis(BS)on growth performance,immune performance and serum antioxidant indexes of broilers challenged with lipopolysaccharide(LPS).A total of 192 one-day-old healthy AA broilers(males and females in half)were randomly divided to 4 treatments as a 2×2 factorial design.The main factors were diets(a basic diet or a experimental diet supplemented with 200 g/t BS)and LPS stress(oral administration of LPS solution or saline),and randomly divided into 1)the basal diet+normal saline group;2)the basal diet+LPS group;3)the experimental diet+normal saline group;4)the experimental diet+LPS group,a total 4 groups,each group composed of 6 replicates with 8 broilers per replicate.The trial lasted for 28 days and was divided into 3 stages,including before challenged with LPS(days 1 to 14),the period of challenged with LPS(days 15 to 21)and the period of recovery(days 22 to 28).The results showed as follows:1)before challenged with LPS,dietary BS significantly increased the average daily gain(ADG)of broilers(P<0.05).LPS challenge significantly decreased ADG(P<0.05)during the period of challenged with LPS and the period of recovery.The ADG of broilers with BS diet was significantly higher than that of broilers without BS diet(P<0.05).During the period of recovery,dietary BS significantly decreased the feed conversion ratio(FCR)(P<0.05).2)On day 21 and 28,under LPS stress,LPS challenged significantly increased the spleen index(P<0.05),dietary BS significantly decreased the spleen index on day 28(P<0.05).During the whole period of experiment,dietary BS and LPS challenge had no significantly effects on thymus index and Bursa index(P>0.05).3)On day 21,under LPS stress,LPS challenge significantly increased the content of immunoglobulin G(IgG)in serum of broilers(P<0.05),and dietary BS significantly decreased the content of immunoglobulin A(IgA)in serum of broilers(P<0.05).On day 28,there was no significantly effect on immunoglobulin contents in experimental groups(P>0.05).4)On day 21,compared with the basal diet,dietary BS had no effects on the contents of interleukin(IL)-1β、IL-6 and tumor necrosis factor-α(TNF-α)(P>0.05).LPS challenge significantly increased the contents of IL-1β,IL-6(P<0.05).Under LPS stress,dietary BS significantly decreased the contents of IL-10 and TNF-α(P<0.05).On days 28,under LPS stress,dietary BS significantly decreased the contents of corticosteronr(CORT)and IL-1β(P<0.05).Compared with unstressed group,LPS challenge significantly increased the contents of IL-6 and TNF-αin serum(P<0.05),but had no effects on the content of IL-10 in serum(P>0.05).5)On day 21,under LPS stress,dietary BS significantly increased the total antioxidant capacity(T-AOC),significantly decreased the content of malondialdehyde(MDA)in serum(P<0.05),and significantly increased the activity of catalase(CAT),but had no effects on the activity of superoxide dismutase(SOD)(P>0.05).On day 28,LPS challenge significantly decreased on the activity of SOD(P<0.05),and had no effect on T-AOC,MDA content and CAT activity in serum(P>0.05).In conclusion,dietary BS can alleviate the decrease of growth performance of broilers caused by immune stress,improve the serum antioxidant performance and inhibit the increase of serum inflammatory cytokine contents,and enhance the body immunity.Therefore,BS can reduce the damage of animal body caused with LPS challenge.