Effects Of GML On Laying Performance,antioxidant,immune Function And Intestinal Microflora Of Laying Hens

Glycerol Monolaurate（GML）is a commonly used food additive,which has bacteriostatic and antiviral effects and has the potential to be used as a feed additive.In this study,Hyline brown hens were selected as the research object to explore the effects of GML on laying performance,egg quality,antioxidant function,immune function,intestinal structure and intestinal microbe of laying hens,and to provide theoretical basis for the application of GML as feed additive.A total of 480 healthy hyline brown laying hens with similar body weight at 54 wks were randomly divided into 5 treatments with 8 replicates per treatment and 12 hens per replicate.The hens were fed 0,100,200,300 and 400 mg/kg GML,respectively.Prefeeding lasted for 1 week,and the formal experiment lasted for 8 weeks.The test results are as follows:1.Laying performance and egg quality: compared with the control group,the supplementation of300 mg/kg and 400 mg/kg GML significantly increased the average egg weight（P<0.05）,had no effect on egg production rate,daily feed intake and feed to egg ratio（P>0.05）.300 mg/kg and 400 mg/kg GML significantly increased protein height and Hastelloy unit（P<0.05）,had no effect on eggshell thickness,eggshell strength and eggshell shape index（P>0.05）.2.Antioxidant and immune function: Compared with the control group,dietary 200 mg/kg GML can significantly increase the contents of SOD,GSH-Px and T-AOC in serum（P<0.05）,300 mg/kg GML could also significantly increase serum GSH-Px content（P<0.05）,200 mg/kg and 300 mg/kg GML significantly decreased serum MDA content（P<0.05）.300 mg/kg GML significantly increased the serum Ig G content（P<0.05）,GML did not affect the contents of serum Ig M,HDL-C and LDL-C（P>0.05）.The expression levels of TLR4,IL-1β and TNF-α in spleen were significantly decreased by 300 mg/kg GML（P<0.05）,200 mg/kg GML also significantly decreased TNF-α expression in spleen（P<0.05）,400 mg/kg GML significantly reduced the expression of TLR4 in spleen（P<0.05）,GML did not affect the expression of TGF-β3 in spleen（P>0.05）.The expressions of TLR4,IL-1β and TNF-α in jejunum were significantly decreased at 300 mg/kg and 400 mg/kg GML（P<0.05）,significantly increased the expression level of TGFβ3 in jejunum（P<0.05）,200 mg/kg GML also significantly decreased the expression of IL-1β in jejunum（P<0.05）.3.Intestinal structure and microflora: Compared with the control group,supplementation of 300mg/kg GML significantly increased the height of jejunum villus and the ratio of villus to crypto（P<0.05）,and had no significant effect on duodenum and ileum intestinal structure（P>0.05）.Bacteroidota in 200 mg/kg GML test group was significantly higher than that in control group（P<0.05）,and no significant change in Firmicutes,Fusobacteriotaand Proteobacteria compared with the control group（P>0.05）,there was a significant difference in species composition between the treatment group and the control group（P=0.098）.Compared with the control group,Prevotellaceae in experimental group was significantly enriched（P<0.05）.In conclusion,dietary GML supplementation can improve egg weight and egg quality,enhance antioxidant level and immune performance of laying hens,improve intestinal villus height of laying hens,affect intestinal microbial colony structure of laying hens,and improve the relative abundance of intestinal probiotics.