Abstract
This study aimed to investigate the effects of Bacillus amyloliquefaciens LFB112 on the growth performance, carcass traits, immune response, and serum biochemical parameters of broiler chickens. A total of 396 1 day old, mixed-sex commercial Ross 308 broilers with similar body weights were allotted into six treatment groups. The assigned groups were the CON group (basal diet with no supplement), AB (antibiotics) group (basal diet + 150 mg of aureomycin/kg), C+M group (basal diet + 5 × 108 CFU/kg B. amyloliquefaciens LFB112 powder with vegetative cells + metabolites), C group (basal diet + 5 × 108 CFU/kg B. amyloliquefaciens LFB112 vegetative cell powder with removed metabolites), M group (basal diet + 5 × 108 CFU/kg B. amyloliquefaciens LFB112 metabolite powder with removed vegetative cells), and CICC group (basal diet + 5 × 108 CFU/kg Bacillus subtilis CICC 20179). Results indicated that chickens in the C+M, C, and M groups had higher body weight (BW) and average daily gain (ADG) (p < 0.05) and lower feed conversion ratio (FCR) (p = 0.02) compared to the CON group. The C+M group showed the lowest abdominal fat rate compared to those in the CON, AB, and CICC groups (p < 0.05). Compared to the CON group, serum IgA and IgG levels in the C+M, C, and M groups significantly increased while declining in the AB group (p < 0.05). B. amyloliquefaciens LFB112 supplementation significantly reduced the serum triglyceride, cholesterol, urea, and creatinine levels, while increasing the serum glucose and total protein (p < 0.05). In conclusion, B. amyloliquefaciens LFB112 significantly improved the growth performance, carcass traits, immunity, and blood chemical indices of broiler chickens and may be used as an efficient broiler feed supplement.
Highlights
Dietary antibiotics have brought great benefits to the development of the livestock and poultry industry for more than 60 years
The average daily gain of birds fed with Bacillus amyloliquefaciens LFB112 and its metabolites increased by 13.4%, 13.2%, and 11.3% and by 5.3%, 5.2%, and 3.3% compared with the control and antibiotic groups, respectively
Administration of B. subtilis as a direct-fed microorganism (DFM) improved body weight (BW), BWG, and average daily feed intake (ADFI) in comparison to those fed with untreated diet and to those administered an antibiotic growth promoter (AGP), suggesting that DFM administration may be used as an alternative to AGP [46]
Summary
Dietary antibiotics have brought great benefits to the development of the livestock and poultry industry for more than 60 years. Antibiotic residues in animal products are essentially a double-edged sword as they threaten human health, as well as lead to possible antibioticresistant pathogenic bacteria and intestinal flora disorders [5,6]. In response to this situation, growth-promoting antibiotics have been prohibited as feed supplements in Europe since 2006, in the United States since 2014, and in China since 2020. Probiotics are considered ideal substitutes for antibiotics due to their nontoxic effects, lack of residue, and significant effects on animal health and production
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