Administrating antibiotics to young piglets may have short- and long-term consequences on the gut microbiota. We hypothesised that these consequences may be alleviated by concurrent probiotic administration. The study objective was to investigate the effect of administrating gentamicin and a mixture of Bacillus (B.) licheniformis, B. subtilis and B. amyloliquefaeceans spores on the gut microbiota of piglets pre- and post-weaning. Twenty-four sows and their litters were randomly allocated to four treatment groups receiving; a) Bacillus spore mixture (six B. subtilis, two B. amyloliquefaeceans, and one B. licheniformis) fed to sows and piglets (PRO); b) gentamicin (5 mg per day) administered to piglets on day 4, 5, and 6 of age (AB); c) Bacillus spore mixture fed to sows and piglets, and gentamicin to piglets (PRO+AB); or d) no administration of probiotics or antibiotics (CTRL). Faecal and digesta samples were collected repeatedly during the study. Selected samples were subjected to 16S rRNA gene sequencing, culture counts, and organic acid, biogenic amine and tissue gene expression analysis. Treatment had a significant effect on the faecal microbial community composition on day 28 and 42, and colonic community on day 28. Faecal species richness (observed and estimated) and Shannon index, and colonic species richness, were higher in AB compared to PRO piglets on day 28, and were not significantly different from day 42. PRO piglets had the highest faecal concentration of iso-butyric acid on day 7 and a higher butyric acid concentration compared to CTRL piglets. We conclude that gentamicin and Bacillus spores influence the gut microbial diversity of piglets, although administration of gentamicin did not result in dysbiosis as hypothesised.

The present study investigated the effect of feeding bovine colostrum (BC) to piglets in comparison with feeding a milk replacer (MR) and conventional rearing by the sow on the intestinal immune system and number of enterotoxigenic Escherichia coli (ETEC) colonising the intestinal tissue. Piglets (23-d-old) were allocated to one of the following four groups: (1) killed at the beginning of the experiment (Base); (2) separated from the sow and fed BC (BC-fed); (3) separated from the sow and fed a MR (MR-fed); (4) kept with the sow (Sow-Milk). Blood was sampled on days 1 and 8, and faecal samples were collected on days 1, 3, 5 and 8. On day 8, piglets were killed and gastrointestinal digesta and intestinal segments were collected. The frequency of diarrhoea was found to be higher (P≤ 0·019) in MR-fed piglets than in BC-fed and Sow-Milk piglets. Piglets from the MR-fed group had the lowest lactic acid bacteria:haemolytic E. coli ratio (P treat= 0·064) in the faeces. The number of E. coli colonising the intestinal tissue was higher (P< 0·001) in piglets from the MR-fed group than in those from the BC-fed and Sow-Milk groups. Piglets from the Sow-Milk group had a higher (P= 0·020) mucosal IgG concentration than those from the MR-fed group, but did not exhibit any difference when compared with piglets from the Base and BC-fed groups. Piglets from the BC-fed group exhibited a reduced (P≤ 0·037) expression level of Toll-like receptor-4 in the intestinal mucosa when compared with those from the MR-fed and Sow-Milk groups. The expression level of IL-2 was higher (P≤ 0·051) in piglets from the MR-fed group than in those from the other treatment groups. In conclusion, feeding BC rather than MR to the piglets reduced the colonisation of intestine by ETEC and modulated the intestinal immune system, whereas no differences were observed in piglets fed BC and conventionally reared by the sows.

The aim of this study was to characterise the gut microbiota composition of piglets fed bovine colostrum (BC), milk replacer (MR) or sow milk (SM) in the post-weaning period. Piglets (n 36), 23-d old, were randomly allocated to the three diets. Faecal samples were collected at 23, 25, 27 and 30 d of age. Digesta from the stomach, ileum, caecum and mid-colon was collected at 30 d of age. Bacterial DNA from all samples was subjected to amplicon sequencing of the 16S rRNA gene. Bacterial enumerations by culture and SCFA analysis were conducted as well. BC-piglets had the highest abundance of Lactococcus in the stomach (P < 0·0001) and ileal (P < 0·0001) digesta, whereas SM-piglets had the highest abundance of Lactobacillus in the stomach digesta (P < 0·0001). MR-piglets had a high abundance of Enterobacteriaceae in the ileal digesta (P < 0·0001) and a higher number of haemolytic bacteria in ileal (P = 0·0002) and mid-colon (P = 0·001) digesta than SM-piglets. BC-piglets showed the highest colonic concentration of iso-butyric and iso-valeric acid (P = 0·02). Sequencing and culture showed that MR-piglets were colonised by a higher number of Enterobacteriaceae, whereas the gut microbiota of BC-piglets was characterised by a change in lactic acid bacteria genera when compared with SM-piglets. We conclude that especially the ileal microbiota of BC-piglets had a closer resemblance to that of SM-piglets in regard to the abundance of potential enteric pathogens than did MR-piglets. The results indicate that BC may be a useful substitute for regular milk replacers, and as a feeding supplement in the immediate post-weaning period.