Effect Of Yeast Polysaccharide Addition To Rations On Performance,Biochemical Parameters And Intestinal Health Of Late Laying Hens

Improving the production performance and egg quality of late laying hens can improve the economic benefits of egg production.As a functional polysaccharide,yeast polysaccharide can promote growth,improve production performance,enhance immunity and protect intestinal health.The aim of this study was to investigate the effects of different doses of yeast polysaccharides in the diet on the production performance,immune performance,serum biochemical index and antioxidant performance of late laying hens.A total of 720 52-week-old Hyland Brown hens were randomly divided into 4 groups of 6 replicates each,with 30 hens in each replicate.The control group（Group C）was fed the basal diet,while the experimental groups YT1,YT2 and YT3 were supplemented with 500 mg/kg,1 000 mg/kg and 1 500 mg/kg of yeast polysaccharide respectively.The test period was 7 d for the pre-test and 36 d for the test.the results were as follows.1)The addition of yeast polysaccharide could improve egg production performance and some egg quality.Compared with the control group,the egg production rate of YTI group and YT2 group increased by 0.73%and 4.29%respectively after feeding yeast polysaccharide,showing an increasing trend（P=0.063）,the average daily egg weight of the test groups YT1 group,YT2 group and YT3 group had an increasing trend（P=0.091）,the differences in feed-to-egg ratio and average daily feed intake were not significant（P>0.05）;after feeding yeast polysaccharide the three The egg weight and yolk weight of the three experimental groups were significantly higher than those of the control group C（P<0.05）.The brightness L values of egg shell colour in the three experimental groups YT1,YT2 and YT3 were 0.75%,2.59%and 1.06%lower than those of the control group,respectively,but the differences in egg white height,yolk colour,Hastelloy units,egg shell strength,egg shell thickness,egg shape index,brightness L*,redness a*and yellowness b*were not significant（P>0.05）.2)The addition of yeast polysaccharide improved the immune performance of the laying hens.Compared with the control group,the spleen index tended to increase in each test group（P=0.076）.The difference in IgM content in serum was significant in the YT3 group after feeding yeast polysaccharide（P<0.05）,but there was no significant difference in the YT1 and YT2 groups.There was no significant difference in IgG content in serum between the three test groups（P>0.05）.3)The addition of yeast polysaccharide could regulate liver function and improve lipid metabolism in laying hens.Compared with the control group,the liver index of the YT2 group was significantly higher than that of the C,YT1 and YT3 groups（P<0.05）;the ALT activity of the test groups YT1 and YT2 and the AST activity of the YT1 group were significantly lower（P<0.05）.CHO levels were significantly lower in all three test groups（P<0.05）and there was a trend towards lower triglycerides（TG）and low-density lipoproteins（LDL）（P=0.075,P=0.057）.4)The addition of yeast polysaccharide enhanced the antioxidant capacity of the organism.Compared with the control group,the MDA content in the serum of YT1 group and YT2 group was significantly reduced（P<0.05）;the CAT activity in the serum of YT2 group was significantly increased（P<0.05）;the GSH-PX activity in the serum of YT1 group and YT3 group was significantly increased（P<0.05）;the rest of the antioxidant indexes in the serum were not significantly different（P>0.05）;in the liver antioxidant The GSH content in the liver of YT2 group was significantly increased（P<0.05）.The MDA content in the liver of the YT2 and YT3 groups was significantly reduced（P<0.05）,and the CAT activity in the liver of the YT1,YT2 and YT3 groups was significantly increased（P<0.05）.5)Addition of yeast polysaccharide improved intestinal structure.Compared with the control group,the ileal villi length was significantly increased in the YT1,YT2 and YT3 groups（P<0.05）;and the villi length/crypt depth（V/C）was significantly increased in the three test groups（P<0.05）,but the difference in crypt depth was not significant（P>0.05）.Compared with the control group,the expression levels of TNF-α mRNA in ileal tissues of YT2 and YT3 groups were significantly lower（P<0.05）;however,there was no significant difference in the expression levels of IL-2 and IL-10 mRNA in ileal tissues of each test group（P>0.05）.The expression levels of tight junction protein Occludin gene were significantly up-regulated in YT1 group（P<0.05）,but Claudin and MUC2 gene mRNA expression levels were not significantly different（P>0.05）.6)Addition of yeast polysaccharide can regulate the structure of intestinal flora.The results of intestinal 16S sequencing showed that,compared with the control group,at the ileal phylum level,the relative abundance of the ileal thick-walled phylum decreased in the YH2 group,while the relative abundance of the phylum Actinobacteria,Bacteroidetes and Aspergillus increased;at the genus level,the relative abundance of the genus Lactobacillus decreased in the test group,but the relative abundance of the dominant genera Bacteroidetes and Bifidobacterium increased.In the analysis of microbial markers related to the intestinal flora,the control group was missing and there were no significant differential species.5 differential microbial species were found in the YH2 group,with Lactobacillus spp.being the most influential differential genus.At the cecum phylum level the control cecum thick-walled phylum was relatively richer than the test group YM2,but the test group YM2 had an increased abundance of the phylum Bacteroides and Actinomycetes compared to the control group.At the genus level,the relative abundance of Bacillus spp,Lactobacillus spp.and Flavobacterium spp.increased in the YM2 group compared to the control group.In the analysis of microbial markers related to the intestinal flora,the control group differential species were missing and there were two differential microbial species in the YM2 group,with Prevotella phylum being the most influential differential family.In summary,the addition of yeast polysaccharides can improve the production performance,immune function and antioxidant function of the body of late laying hens,improve the morphological structure of the intestine and regulate the composition of the intestinal microflora of the ileum and cecum,reduce the occurrence of inflammation in the intestinal tissues and enhance the protective function of the intestinal barrier,regulate the intestinal immune response and benefit intestinal health.