Effect of Chitosan on Growth Performance and Immunity in Weanling Pigs Challenged with Escherichia coli

The experiment was conducted to study effects of chitosan on growth performance and immunity in weanling piglets.Fifty piglets with an average body weight of(6.62±0.59) kg were challenged with enterotoxigenic Escherichia coli(1×109 cell per head) during adaptation period and randomly assigned to 5 groups with 10 replicates per group and 1 piglet in each replicate.The piglets in control group were fed basal diet,and the others in experimental groups were fed the basal diet supplemented with 50 mg/kg chlortetracycline,200,300 or 400 mg/kg chitosan,respectively.The experiment lasted for 21 days.The results showed as follows:1) compared with the control group,in every experimental group,average daily feed intake was improved(P0.05),the ratio of feed to gain and diarrhea ratio were decreased,and the average daily gain was increased by 15.8%,9.2%,16.8% and 21.1%(P0.05),respectively.2) Compared with the control group,the serum immunoglobulin G(IgG) and immunoglobulin M(IgM) levels,relative expression levels of interleukin-1β(IL-1β),interleukin-6(IL-6) and tumor necrosis factor-α(TNF-α) mRNA in ileum mucosa were improved in the chitosan groups,but decreased in the chlortetracycline group.The IgG and IgM levels in the 300 and 400 mg/kg chitosan groups were significant higher than those in the chlortetracycline group(P0.05),and the IgG level in the 400 mg/kg chitosan group was significant higher than that in the control group(P0.05).The relative expression level of IL-1β and TNF-α mRNA in the three chitosan groups was significant higher than those in the chlortetracycline group(P0.05),and the relative expression levels of IL-6 mRNA in the 300 and 400 mg/kg chitosan groups were significant higher than that in the chlortetracycline group(P0.05).These results indicate that supplemented with 200,300 and 400 mg/kg chitosan in diets can improve growth performance,decrease diarrhea ratio and enhance non-specific immunity of weanling piglets,furthermore,those effects have enhancing trend with increasing the concentration of chitosan in diets.