Writing in the Asian Australian Journal of Animal Sciences, the authors say B. subtilis KN-42 improved the bacterial diversity of the intestinal environment, increased the number of Lactobacillus and reduced the number of E. coli in the faeces of weaned piglets.
“These results suggest that B. subtilis KN-42 can serve as an alternative to antibiotics in diets for weaned piglets,” said project lead, Yunxiang Liang, who is based at Huazhong Agricultural University in China.
Weaning heightens stress for piglets
Weaning is a stressful period in the life cycle of pigs - it is associated with changes in diet, gut environment and gut morphology, and thus may result in low growth rate, high diarrhea incidence and imbalanced intestinal microecology.
The authors note previous research on how probiotics can help address such challenges for piglet producers.
But they say other trials have shown zero effect from the addition of the micro-organisms to feed. Thus they concluded: “The effect of probiotics depends on the combination of selected bacterial genera, their doses, and feed composition.”
Bent Borg Jensen, senior researcher in the Department of Animal Science at Denmark’s Aarhus University, concurs.
He told this publication recently there are indicators that the bacillus strain of probiotics is beneficial for pigs but “we need more strain and dosage specific data to confirm its immune strengthening abilities.”
The study details
The goal of their particular study, said the Chinese team, was to investigate the effect of different doses of B. subtilis KN-42 on the growth performance, diarrhea incidence, fecal Lactobacillus, E. coli and bacterial diversity of weaned piglets.
“Several strains of B. subtilis can be used as feed additives, and no safety concerns are identified when used in direct-fed microbial products.
We hypothesized that B. subtilis would help the balance of microflora by stimulating the beneficial bacteria, thereby improving gut health, reducing diarrhea incidence indirectly, and enhancing the growth performance,” said the team.
The researchers said denaturing gradient gel electrophoresis (DGGE) was used to characterize the bacterial diversity of faeces, and real-time polymerase chain reaction (PCR) was used to measure the copy number of Lactobacillus and E. coli.
The study involved a total of 360 piglets that had been weaned around 26 days of age. The authors said these were randomly allotted to five treatment groups - four pens per treatment with 18 pigs per pen - for a 28-day trial.
They said the various feeds used included a negative control, which consisted of a basal diet without any antimicrobial (NC), the positive control which included 120 mg per kg of feed of neomycin sulfate (PC) and three basal diets supplemented with 2×109 (L), 4×109 (M) and 20×109 (H) CFU per kg feed of B. subtilis KN-42.
Feed intake and body weight were measured at the end of each phase to determine average daily weight gain and feed intake, as well as feed efficiency, said the research team.
The scientists found that during the overall period, average daily weight gain and feed efficiency of piglets were higher in groups PC, M, and H than those in the NC group and all probiotic and antibiotic groups had a lower diarrhea index than the negative control cohort.
The result of the DGGE analysis showed that supplementation of B. subtilis KN-42 to the animals' feed changed the bacterial communities, with a higher bacterial diversity and band number in group M than in the other four groups, said the Chinese scientists.
The real-time PCR analysis showed that the relative number of Lactobacillus were higher in groups PC and H than in group NC and that adding B. subtilis KN-42 to the weaned piglets' diet also reduced the relative number of E. coli, they added.
“These results suggest that dietary addition of B. subtilis KN-42 can improve the growth performance and gastrointestinal health of piglets,” said the authors.
The growth performance, they said, may be linked to the reduction in the occurrence of diarrhea, a finding that is consistent with previous research into the benefits of probiotics in pigs.
Source: Asian Australian Journal of Animal Sciences
Title: Effects of Bacillus subtilis KN-42 on Growth Performance, Diarrhea and Faecal Bacterial Flora of Weaned Piglets
Authors: Y. Liang et al