| Mediumchain fatty acid(MCFAs)have become a new hot spot in the research of antibiotic substitutes.In this study,glycerol monolaurate(GML)was used to study its effects on growth performance,immune function and intestinal health of yellow-feathered broilers.This study is divided into three experimentsExperiment 1: the inhibitory effect of different MCFAs and their esters on pathogenic bacteria.the bacteriostatic effects of lauric acid,glycerol monooctanoate,glycerol monolaurate and glycerol octanoate on Escherichia coli,Staphylococcus aureus,Salmonella enteritis and Salmonella pullorum were studied by shaking flask method.The results showed that lauric acid,glycerol monooctanoate and glycerol monolaurate had significant inhibitory effects on Escherichia coli,Staphylococcus aureus and Salmonella enteritis.Among them,glyceryl monolaurate has the best effect.Experiment 2: to study the effects of GML on growth performance,immune function,volatile fatty acids and cecal microbial community in broilers.The480one-day-old yellow-feathered broilers were randomly divided into 4 groups with 8replicates in each group and 15 broilers in each group.The control group(NCO)was fed with non-resistant basal diet,the antibiotic control group(ANT)was supplemented with chlortetracycline of 30 mg/kg in the basal diet,group 1(GML1)was supplemented with 500 mg/kg GML in the basal diet,and group 2(GML2)was supplemented with 1000 mg/kg GML in the basal diet.The results showed that the average daily gain of broilers supplemented with GML was significantly higher than that of the control group(P < 0.05),and the levels of Ig M and Ig Y in serum of broilers supplemented with 500 mg/kg and 1000 mg/kg were significantly higher than those of the control group(P < 0.05).At 28 days of age the concentrations of acetic acid,propionic acid,n-butyric acid,valeric acid and isovaleric acid in the colon of broilers supplemented with 1000 mg/kg g GML were significantly higher than those of NCO group(P < 0.05).The richness and diversity of broiler microbiota were improved by adding GML.The number of acidogenic bacteria increased,and at the age of 56 days,the addition of GML decreased the number of pathogenic bacteria in the cecum of broilers.Experiment 3: to study the effects of GML on growth performance,immune function,VFAs and cecal microbial community in broilers stimulated by LPS.A total of 360 1-day-old yellow-feathered broilers were randomly divided into 3 groups with8 replicates in each group and 15 broilers in each group.The control group(NCO)was fed with basal diet,the antibiotic control group(ANT),was fed with chlortetracycline of 30 mg/kg,and GML was fed with 500 mg/kg GML in the basal diet for 56 days.The virus was challenged by LPS on the 56 th,58 th and 60 th day.The results showed that GML could significantly increase the contents of acetic acid and isovaleric acid in the colon of broilers(P<0.05),decrease the depth of jejunal crypt(P< 0.05)and increase the ratio of intestinal gland(P < 0.05).With the addition of GML,the richness and diversity of broiler microbiota were improved,the number of Bacterium decreased and the number of Bacteroides increased.The results showed that GML could alleviate the immune stress induced by LPS stimulation in broilers.To sum up,GML can improve the growth performance of broilers,enhance the immune function of broilers,help to balance the intestinal microorganisms of broilers,increase the content of VFAs in the intestines,reduce the inflammatory response to broilers stimulated by LPS,improve the intestinal barrier function of broilers,and balance the intestinal microflora of broilers. |
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