Study On Intestinal Microbiota And Mucosal Immune Markers Of Altay Sheep With Different Growth Rates

The intestinal microbiota plays an important role in the growth and development of the body.It establishes a healthy symbiotic relationship with the host through the regulation of the intestinal mucosal immune system to maintain intestinal homeostasis.Different growth rates will affect the intestinal microbiota and the mucosal immune system,and there is a correlation between them.Therefore,in this experiment,the concentration of intestinal microbiota and mucosal immune markers in Altay sheep with different growth rates was studied to explore the effect of growth rate on them and the correlation between the two factors.Secondly,the growth rate of Altay sheep was changed by diet to further study the changes of intestinal microbiota and mucosal immune markers,and to explore the relationship between sheep growth and development,intestinal microbiota and mucosal immunity.According to the experimental design,the numbers of ear tags were used to record the birth weight of 300 Altay lambs,and they were fed normally to 6-month-old.Then the sheep whose daily weight gain was top 10%was defined as the fast growth group,and these whose daily weight gain was bottom 10%was devided into the slow growth group.Twelve lambs of similar weight were randomly selected in each group,and these choosed from fast-growing group were randomly divided into a low energy level diet-restricted group(HR,n=6)and a standard energy level diet control group(HC,n=6);at the same time,those choosed from the slow growth group were randomly divided into a high energy level diet feeding group(LA,n=6)and a standard energy level diet control group(LC,n=6).After 7 days of pre-feeding,recorded their initial weight.Then the HR,HC,LC,and LA groups were fed diets with 75%,100%,100%,and 125%of energy intakes,respectively.And feeding trials were continued for 30 days.Animals were fed twice daily,once in the morning and once in the evening,drinking water freely.At the end of the feeding period,the animals were weighed and collected serum to detect hormone and immunomarker concentration,after that they were euthanized to collect intestinal contents from the same site,extract DNA from these samples,and detection was performed using the Illumina Miseq sequencing platform.Intestinal segment tissue and intestinal mucosa were collected to extract proteins,and the concentration of immune markers was measured using an enzyme-linked immunosorbent kit.Finally,the correlation between microbiota and immune markers was analyzed.The results are as follows:1.Under the same feeding standard,there was difference in the composition of intestinal microbiota of Altay sheep with different growth rate.The abundance of Firmicutes,Actinobacteria,Saccharibacteria,Peptostreptococcaceae and Bifidobacteriaceae in the HC group was higher than that in the LC group,but the abundance of Proteobacteria and Paeniclostridium in the LC group was higher than that in the HC group.Meanwhile,the concentration of IgG in serum of the HC group was significantly higher than that of LC group(P<0.05).The concentrations of IgA and IL-10 were significantly higher than those of LC group(P<0.01).The concentrations of IL-2,IL-6 and TNF-α were significant(P<0.01)lower than those in the LC group;the concentrations of IL-2 in the intestinal tissue of the HC group were significantly lower than those in the LC group(P<0.05).In the analysis of the correlation between the microbiota and the immunemarkers,the bacteria communities that have significant correlation with the immune markers were mainly composed of Christensenellaceae,Ruminococcaceae,Paeniclostridium,Turicibacter and Elusimicrobium.2.In the experiment on the effect of diet on growth rate,after inhibiting the growth rate,the abundance of the Firmicutes,Tenericutes,and Bacteroidetes was increased,and the abundance of the Proteobacteria,Actinobacteria,and Paeniclostridium decreased.And the concentrations of IL-2,IL-6,IL-12 and TNF-α in serum increased significantly(P<0.01),the concentrations of IgA、IgG and IL-10 in serum decreased significantly(P<0.01).After the growth rate was increased,the abundance of the Firmicutes,Lentisphaerae,Paeniclostridium and Prevotellaceae increased,the abundance of the Proteobacteria and Succinivibrio reduced.In serum,the concentration of TNF-α increased significantly(P<0.05),the concentration of IL-12 increased significantly(P<0.01),and the concentration of IgG decreased significantly(P<0.05);the concentration of IL-2 in intestinal tissues decreased significantly(P<0.05).The results showed that the composition of intestinal microbiota of Altay sheep at different growth rates is different;the function of the immune system in the fast-growing group is better than that in the slow-growing group;there is a significant correlation between the intestinal microbiota and immune markers.The results of dietary feeding experiments showed that,regardless of weight gain or loss,the abundance of Firmicutes,Bacteroides,and Peptostreptococcaceae increased,the abundance of Cyanobacteria decreased,and the immune function of the body decreased.According to the results of this study,it can be concluded that the high abundance of Paeniclostridium exists in the slow-growing groups,the abundance change of Saccharibacteria was positively correlated with growth rate,suggested that it is correlated with the growth rate.In summary,there is a correlation between growth rate and intestinal microbiota and mucosal immunity.