B. licheniformis and B. subtilis complex on performance, digestibility, faecal microbiota and noxious gas emissions in pigs

Bacillus spp. are aerobic and endospore-forming bacteria that have recently shown their potential as probiotic candidates because of their survival through the digestive process and germination within the digestive tract. It was hypothesized that dietary supplementation with a B. licheniformis and B. subtilis complex could have beneficial effects on growth performance and faecal noxious gas emissions by improving nutrient utilization and intestinal microbiota balance. Therefore, the aim of the present study was to assess the effects of B. licheniformis and B. subtilis complex (in a 1:1 ratio) supplementation on growth performance, nutrient digestibility, faecal microbiota and faecal noxious gas emissions in growing-finishing pigs. A total of 140 growing pigs ((Landrace × Yorkshire) × Duroc) with an average body weight (BW) of 24.87 ± 1.85 kg were used in a 15-week trial. Pigs were randomly allotted to four experimental diets according to initial BW and gender. There were seven replication pens in each treatment, with five pigs per pen (three barrows and two gilts). Dietary treatment groups were: (1) CON, basal diet; (2) T1, CON + 0.2 g/kg B. licheniformis and B. subtilis complex; (3) T2, CON + 0.4 g/kg Bacillus complex; (4) T3, CON + 0.8 g/kg Bacillus complex. The diets were fed in three phases in mash form, consisting of a growing phase from week 1 to week 6, an early finishing phase from week 7 to week 12 and late finishing phase from week 13 to week 15. The probiotics were included in the diet by replacing the same amount of corn.

As a result, the dietary supplementation showed a linear increase in digestibility of dry matter at weeks 6, 12 and 15 and a linear increase in digestibility of nitrogen at week 12. Supplemented groups also presented a linear increase in faecal Lactobacillus counts at weeks 6 and 12, a linear decrease in ammonia (NH₃) emission at weeks 6 and 12 and a linear decrease in total mercaptan emission at weeks 3, 9 and 15. Overall. The increasing dietary supplementation with the B. licheniformis and B. subtilis complex increased digestibility and faecal Lactobacillus counts and decreased faecal NH₃ and total mercaptan emissions in growing-finishing pigs, emerging as a potential feed additive to reduce noxious gas emissions.

Lan, R., & Kim, I. H. (2019). Effects of Bacillus licheniformis and Bacillus subtilis complex on growth performance and faecal noxious gas emissions in growing-finishing pigs. Journal of the Science of Food and Agriculture, 99(4), 1554-1560. https://doi.org/10.1002/jsfa.9333