贝莱斯芽孢杆菌对金霉素作用下肉鸡生长性能、肠道菌群及其耐药基因的影响研究

Study on The Effects of Bacillus velezensis on Growth Performance,Gut Microbiota and Antibiotic Resistance Genes of Broilers Under The Action of Chlortetracycline

试验旨在研究在饲粮中添加贝莱斯芽孢杆菌H-7对金霉素作用下肉鸡生长性能、肠道菌群和耐药基因的影响。首先挑选体重相近,性别比例相同,健康状态良好的1日龄雏鸡360羽,分为4个试验组,每组6个重复,每个重复15只,分别饲喂含金霉素0、50、150、250 mg/kg的基础日粮,饲喂28 d,确定对肉鸡肠道菌群影响最大的金霉素剂量和作用。随后挑选1日龄雏鸡450羽,分为5个试验组,每组6个重复,每个重复15只。1~7日龄,前4组饲喂基含150 mg/kg金霉素的日粮,7~35日龄时,分别饲喂含0、10^(8)、10^(9) CFU/kg和10^(10) CFU/kg贝莱斯芽孢杆菌的日粮,同时以1~35日龄均饲喂基础日粮的为空白对照组。结果表明,肉鸡盲肠的菌群结构随着时间和金霉素剂量发生变化。尤其是在生命早期7日龄时,中剂量组(150 mg/kg)中有益菌属Bifidobacterium、Lactobacillus丰度显著降低(P<0.05),肠道常见条件致病菌Enterococcus、Enterobacter的丰度上升,且耐药基因(ARGs)丰度上升。金霉素作用7 d后,在饲粮中添加贝莱斯芽孢杆菌H-7可增加肉鸡体重,但对生长性能无显著影响(P>0.05)。显著增加21日龄肉鸡肠道中Firmicutes的相对丰度(P<0.05),降低Bacteroidetes和Proteobacteria的相对丰度,显著提高F/B值(P<0.05)。贝莱斯芽孢杆菌的添加促进Akkermansia、Ruminococcus、Blautia、Bacillus和Lactobacillus等有益菌属的富集,同时降低了四环素类耐药基因的丰度,有助于改善肉鸡肠道的健康水平。

The purpose of this experiment was to study the effect of Bacillus velezensis H-7 supplementation on the growth performance,intestinal flora and ARGs of broilers under the action of chlortetracycline.A total of 3601-day-old chicks with similar body weight,the same sex ratio and good health were selected and divided into 4 experimental groups with 6 replicates per group and 15 chicks per replicate.The basal diets containing 0,50,150 and 250 mg/kg chlortetracycline were fed for 28 days to determine the dosage and effect of chlortetracycline that had the greatest impact on the gut microbiota of broilers.Then 4501-day-old chicks were selected and divided into 5 test groups,with 6 replicates per group and 15 chicks per replicate.For 1-7 days,the first 4 groups were fed with diets containing 150 mg/kg chlortetracycline,and for 7-35 days,the diets containing 0,10^(8),10^(9) CFU/kg and 10^(10) CFU/kg Bacillus velezensis were fed respectively,at the same time,the control group was fed basal diet for 1-35 days.The results showed that the structural composition of gut microbiota of broiler cecum changed with time and chlortetracycline dose.Especially at the age of 7 days in the early life,the abundance of beneficial bacteria such as Bifidobacterium,Lactobacillus in the middle-dose group(150 mg/kg)was significantly decreased(P<0.05),the abundance of common intestinal opportunistic pathogens Enterococcus,Enterobacter and ARGs in broilers have increased.Adding Bacillus velezensis H-7 to the diet increased the weight of broilers,but had no significant effect on growth performance(P>0.05),significantly increased the relative abundance of Firmicutes(P<0.05),decreased the relative abundance of Bacteroidetes and Proteobacteria,and significantly increased F/B in the intestine of 21-day-old broilers after chlortetracycline treatment for 7 days(P<0.05).The addition of Bacillus velezensis promotes the enrichment of beneficial bacteria genera such as Akker-mansia,Ruminococcus,Blautia,Bacillus and Lactobacillus,while it reduces the abundance of tetracycline resistance genes,which helps to improve the health of broiler intestines.