| This experiment was conducted to investigate the effects of bacillus licheniformis H2supplementation on growth performance,intestinal structure and microbiome of broilers with necrotizing enteritis caused by Clostridium perfringens challenge.A total of 240 7-day-old Ross 308 broilers with similar body weight and good health status were randomly divided into negative control group(NC),positive control group(PC),H2 group(H2)and antibiotic group(K)with 4 replicates per group and 15 broilers per replicate.The treatment methods of each group were as follows:NC group was given 1m L of sterilized normal saline by gavage at 15 days of age;From 18 to 22 days of age,1m L sterile liquid mercaptoacetate medium was intragastric daily.PC group,H2 group,K groupwere given coccidiococcus vaccine at 15 days of age;From 18 to 22 days of age,clostridium perfringens type was fed daily.The experiment lasted for 35 d(7-42 days of age),and broilers in four groups were fed the same basal diet,and those in H2 group were fed the basal diet supplemented with 0.01%Bacillus licheniform H2(live spore number was 1×10~9CFU/g).Group K was supplemented with 10 PPM avilamycin.The growth performance,immune organ index,intestinal structure and microbiome of were analyzed.The results showed that the incidence of necrotizing enteritis of broilers in 4 groups from low to high was NC group,K group,H2 group and PC group,The severity of intestinal lesions was observed,and those with scores of 2 or more were regarded as the onset of disease.0 in NC group,12.5%in K group,15.6%in H2 group and 65.63%in PC group were observed,respectively.The average daily gain of broilers in 4 groups at 8-42days of age was 2275.15g,2311.85g,2477.27g and 2157.67g,respectively,with no significant difference.The feed intake of H2 group,NC group,K group and PC group were3590.07g,3923.22g,3702.32g and 3644.25,respectively.There was no significant difference between H2 group,K group and PC group,but extremely significant difference between each group and NC group(P<0.01);The ratios of feed to gain of broilers in H2,NC and K groups were 1.578,1.601 and 1.584,respectively,which were lower than those in PC group(1.689),and the difference was significant(P<0.01).At 28 days of age,the thymus index,spleen index and bursa of Fabricius index in NC group were significantly different from those in PC group(P<0.01).The thymus index and bursa of Fabricius in H2and K groups were significantly different from those in PC group(P<0.01),there was no significant difference in spleen index between PC group and PC group(P>0.05).Thymus index and bursa of Fabricius index in H2 and K groups were significantly different from those in PC group(P<0.01).The Alpha diversity analysis of cecum microbiome showed that shannon index of K group,PC group and H2 group increased successively.For species observation index,K group had the lowest richness and diversity,while PC group had the highest richness and diversity,and there was no significant difference in richness and diversity between K group and PC group.LEf Se analysis results showed that compared with NC group,8 bacteria genera were significantly increased in PC group,4 bacteria genera were significantly increased in K group,and 1 bacteria genus was significantly increased in H2 group,which was an unknown strain that had not been clearly classified.PCoA analysis showed that the difference between H2 group and PC group was greater within the intestinal microflora group,and there were significant differences in the intestinal microflora structure between PC group and NC group.In conclusion,dietary Bacillus licheniformis H2 can reduce the incidence of clostridium perfringen-induced necrotizing enteritis in broilers,significantly increase the average daily gain and decrease the feed to gain ratio of broilers.It has a positive effect on immune capacity of broilers challenged by Clostridium perfringens,and has a positive regulation effect on intestinal structure and microbiome.It is expected to replace antibiotics as a new additive for the prevention and control of necrotizing enteritis in broilers. |
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