Evaluation of Bacillus licheniformis-Fermented Feed Additive as an Antibiotic Substitute: Effect on the Growth Performance, Diarrhea Incidence, and Cecal Microbiota in Weaning Piglets

SIMPLE SUMMARY: Many countries have already restricted the use of antibiotics in preventing diarrhea and improving the growth of weaning piglets. Therefore, exploring alternatives to antibiotics is an urgent unmet need. Bacillus licheniformis-fermented feed additive (BLF)-containing probiotics and antimicrobial substances can diminish the diarrhea incidence of weaning piglets. However, limited information is available in terms of the parallel supplementation of antibiotics and BLF in the diet of weaning piglets. For practical application, this information is important to assess whether BLF can be used as an antibiotic substitute. In this study, the effects of BLF or in combination with bacitracin (antibiotics) on weaning piglets were evaluated. The results showed that the half replacement of bacitracin with BLF leads to positive effects on the alleviation of diarrhea incidence and modification of cecal microbiota in weaning piglets. ABSTRACT: This study investigated the potential of a Bacillus licheniformis-fermented feed additive (BLF) as an antibiotic substitute in weaning piglets. Ninety-six crossbred piglets were randomly allotted into four treatments with three replicate pens per treatment and eight pigs per pen. Piglets were fed diets as follows: a basal diet as control, a basal diet supplemented with bacitracin (30 mg/kg of bacitracin methylene disalicylate), a basal diet supplemented with BLF (1 g/kg of the Bacillus licheniformis-fermented feed additive), and a basal diet supplemented with bacitracin and BLF (15 mg/kg of bacitracin methylene disalicylate and 0.5 g/kg of the Bacillus licheniformis-fermented feed additive). The results showed that replacing all or half the bacitracin with BLF both reduced the incidence of diarrhea in weaning piglets from day 1 to 14. Principal coordinates analysis and a species abundance heat map showed that distinct clusters were formed between groups. Replacing all the bacitracin with BLF reduced bacterial evenness in the cecal digesta of weaning piglets, while the inhibitory effect on bacterial evenness was reversed in the group treated with bacitracin in combination with BLF. These results indicated that the half replacement of bacitracin with BLF was able to decrease the incidence of diarrhea and modify cecal microbiota composition in weaning piglets, suggesting that a Bacillus licheniformis-fermented feed additive has good potential as a suitable alternative to antibiotics use in the swine industry.