Resistant effects determination of Lactobacillus supplementation on broilers to consecutive hydrogen sulfide exposure

Hydrogen sulfide (H₂S) is one of the most irritant gases present in rearing stalls that suppress broilers' healthy growth, which is seriously required an effective alleviation method. In this study, Lactobacillus was supplemented to investigate the alleviative effects on broilers reared under consecutive H₂S exposure. A total of 180 healthy 1-day-old male AA broilers with similar body weight (40.8 ± 1.0 g) were randomly allotted into the control treatment (CON), the hydrogen sulfide treatment (H₂S), and the Lactobacillus supplement under H₂S exposure treatment (LAC) for a 42-d-long feeding process. Growth and carcass performances, immunity-related parameters, intestinal development and cecal microbial communities, and blood metabolites were measured. Results showed that Lactobacillus supplement significantly increased the body weight gain (BWG) while reduced the mortality rate, abdominal fat and bursa of fabricius weight during the whole rearing time compared with H₂S treatment (P < 0.05). Serum LPS, IL-1β, IL-2, and IL-6 contents were observed significantly increased after H₂S treatment while remarkably decreased after Lactobacillus supplementation(P < 0.05). Intestinal morphology results showed a significant higher in the development of ileum villus height (P < 0.05). Cecal microbiota results showed the bacterial composition was significantly altered after Lactobacillus supplement (P < 0.05). Specifically, Lactobacillus supplement significantly decreased the relative abundance of Faecalibacterium, while significantly proliferated the relative abundance of Lactobacillus, Bifidobacterium, Clostridium, and Campylobacter (P<0.05). Metabolic results indicated that Lactobacillus supplement may alleviate the harmful effects caused by H₂S through regulating the pyrimidine metabolism, starch and sucrose metabolism, fructose and mannose degradation, and beta-alanine metabolism. In summary, Lactobacillus supplement effectively increased BWG and decreased mortality rate of broilers under H₂S exposure by enhancing the body's immune capacity, proliferating beneficial microbes (e.g., Lactobacillus and Bifidobacterium), and regulating the physiological pyrimidine metabolism, starch and sucrose metabolism, and beta-alanine metabolism.