The Effects Of Tributyrin Supplementation On Growth Performance And Protection After Challenged With E.coli Of Yellow-feathered Broilers

The objectives of this project were to study the effects of tributyrin on the growth performance of yellow-feathered broiler and the protective effects challenged by Escherichia coli,so as to provide scientific data for tributyrin application in the production of yellow-feathered broiler.Experiment 1 : Total of 360 1-day-old healthy yellow-feathered broilers were selected and randomly divided into 3 groups.Each group had 6 replicates with 20 broilers within each replicate.The experimental period last 63 d.The three groups were: the basal diet group(negative control group,NC),the antibiotic supplementation group(basal diet +250 mg/kg oxytetracycline +200 mg/kg natocin,PC)and the tributyrin supplementation group(basal diet +250 mg/kg tributyrin,TB).The effects of tributyrin on growth performance,serum biochemical indexes,immune performance and cecum microbial diversity of yellow-feathered broilers were investigated.The results showed that:(1)Compared with the NC group,the final body weight(FWB)of broilers aged 42-63 days was significantly increased in the TB group(P < 0.05).Moreover,the average feed per gain(F/G)from 1-63 days was also significantly reduced in the TB group(P < 0.05).(2)Supplementation of tributyrin significantly increased the index of bursa of fabricius(BF)at 42d(P < 0.05),it does not promote the growth and development of other immune organs.(3)Compared with the NC group,the concentration of glutathione peroxidase(GSH-Px)in 42 d broilers was significantly increased in the TB group,with no significant effect on other antioxidant indexes.(4)Compared with NC group,the total protein(TP)and Albumin(ALB)levels of TB group tended to increase and TP at 21 d significantly increased(P< 0.05);Uric acid(UA)concentration in TB and NC groups were significantly higher than that of PC group(P < 0.05);The total cholesterol(TCHOL),creatinine(Cr),aspartate aminotransferase(AST)and alanine aminotransferase(ALT)concentrations tended to be lower in the TB group(P > 0.05);The levels of lactate dehydrogenase(LDH)at 21 d and 63 d as well as γ-Glutamyl transpeptidase(GGT)at 21 d and 42 d were significantly reduced in the TB group(P < 0.05).(5)Regarding the gene expression of ileum tight junction protein,supplementation of tributyrin up-regulate the expression of Nectin-1 genes in 21 d and 42 d broilers(P < 0.05),and tended to up-regulate the expression of Occludin and Claudin-1 in broilers(P > 0.05),indicating that addition of tributyrin can improve the intestinal barrier function.(6)Tributyrin increased gene expression of ileum small peptide transporters caudal-related homeobox 2(CDX2)at 21 d and 63 d,and peptide transporters Oligopeptide transporters 1(Pep T1)at 63d(P < 0.05),as well as a trending effect on the expression of nuclear transcription factor specificity protein 1(Sp1)gene(P >0.05).(7)Tributyrin increased firmicutes and bacteroidetes abundance in TB and PC groups compared to NC group(P < 0.05);the distribution of enterobacteriaceae at21 d in NC group were higher than TB,PC groups(P < 0.05),and the ruminococcaceae at 63 d in NC group was higher than the TB group(P < 0.05).Based on the function prediction chart of FAPROTAX,the main functions of cecum microorganisms in TB group were chemoheterotrophy and fermentation,and the proportion of them were greater than that of NC and PC group.Experiment 2: Total of 60 feathers of 1-day-old healthy yellow-feather broilers,were selected and randomly divided into 3 groups,with 20 broilers in each group.The treatment groups were: NC(blank group)= basal diet,treated with 0.5ml/ normal saline;PC(control group)= basal diet,treated with 0.5ml/ E.coli solution;TB(test group)= basal diet +500mg/kg tributyrin,treated with 0.5ml/ E.coli solution.The effects of tributyrin on the survival rate,protective rate,serum biochemical indexes,antioxidant performance,blood,ileum cytokines,and intestinal microbial diversity of broilers challenged with E.coli were studied.The results showed that :(1)The survival rate and protection rate of NC group were 100%,the infection rate was 0%.The survival rate,infection rate and protection rate of PC group were 47.37%,84.21%and 15.39% respectively.The survival rate of TB group was 75%,the infection rate was 20% and the protection rate was 80%.The survival rate and protection rate of TB group were lower than that of NC group,but higher than that of PC group,and the infection rate was lower than that of PC group,indicating that tributyrin had a protective effect on broilers after E.coli challenged.(2)The blood levels of TG and AST in TB group were significantly reduced(P < 0.05),and the uric acid content was reduced(P > 0.05).(3)Tributyrin increased the superoxide dismutase(SOD)content and antioxidant capacity(P < 0.05).(4)Tributyrin decreased the level of tumor necrosis factor-α(TNF-α)in the serum(P < 0.05),and increased the level of secretory immunoglobulin A(s Ig A)(P < 0.05).(5)The liver index of the PC and TB groups were significantly higher than that of the NC group(P < 0.05),and the spleen indexes of the NC and TB groups were significantly lower than that of the PC group(P < 0.05).(6)Tributyrin improved the relative abundance of firmicutes,lactobacillus in the intestinal tract of broilers(P > 0.05),indicating its effects on inhibiting the growth of harmful bacteria and protecting the intestinal health.In conclusion,dietary supplementation of tributyrin can improve the growth performance of broilers,the body immunity,the expression of Nectin-1 gene of ileal tight junction protein,CDX2 and Pep T1 genes of small peptide transporter,and the intestinal microbial diversity.It can reduce the infection rate and death rate of broilers and the concentratons of cytokines IL-6 and TNF-α in the serum,and improve the survival rate and antioxidant capacity after the challenged with E.coli.