Potential effect of two Bacillus probiotic strains on performance and fecal microbiota of breeding sows and their piglets

Abstract

The effect of long-term administration of two Bacillus strains was tested on 98 breeding sows and their litters allotted into three treatments: a control group (CON); supplemented with 5 × 108 cfu/kg B. subtilis - 541 (BSU); or with 5 × 108 cfu/kg B. amyloliquefaciens - 516 (BAM). Reproductive and performance variables were recorded over three cycles with 56 dams remaining through the third lactation. Blood and fecal samples were taken longitudinally from 12 sows per treatment on days 8 and 21 of the third lactation and milk samples were taken on day 21. Feces from one piglet per litter was sampled on days 21 and 33 and jejunal gene expression was assessed in two piglets on day 21. Changes in fecal microbiota were assessed by 16S rRNA gene sequencing (Illumina MiSeq) and gene expression by Open-Array technology. Metabolomic responses were analyzed in milk by NMR and Ig-G and Ig-A specific antibodies were determined by ELISA. No significant differences were observed on feed intake, body weight, or fat mobilization of the sows. However, a significant increase in the total number of piglets born was observed in supplemented sows. Although the increase was seen from the first cycle with BAM, improvements were not seen with BSU until the third cycle. BAM also increased the number of born-alive and weaned piglets. NMR analysis showed an impact of BAM on milk composition. No differences were found in milk or blood immunoglobulins. A different structure of the fecal microbiota was found in supplemented sows, with changes across phylum, family, and genus. These changes were greater at day 8, suggesting a relevant role of probiotics establishing a new intestinal balance after labor. Shifts in the microbiota were also seen in the piglets, with a clearer impact post-weaning than in suckling. In this regard, correlations between microbial groups of sows and piglets showed a higher link with weaned (d33) than with suckling pigs (d21), reinforcing the idea of an early maternal carry-over. No changes due to treatment in jejunal gene expression were detected; however, piglet size had a clear impact on different genes. In summary, the addition of both probiotics, and particularly Bacillus amyloliquefaciens, demonstrated potential benefits on the prolificacy of sows. Daily feeding of Bacillus amyloliquefaciens resulted in an increase in the number of weaned piglets. The high correlations between the compositions of the microbiota of sows and their piglets are evidence of maternal imprinting, with effects lasting beyond weaning.

Keywords: Bacillus amyloliquefaciens; Bacillus subtilis; microbiota; piglet; probiotic; sow.

Figure 1.

Partial least squares discriminant analysis (PLS-DA) scores plot scaling NMR data from CON and BSU (a); and projection of samples from BAM (b). CON = Control; BSU = Bacillus subtilis; BAM = Bacillus amyloliquefaciens.

Figure 2.

NMDS of the relative abundances of ASV in sow fecal content based on Bray-Curtis distance (stress = 0.157) and grouped by sampling day (d8 after farrowing vs. d21 after farrowing). In order to facilitate the distinction between experimental treatments from (a), the same NMDS figure has been placed in parallel as (b) with the three diets highlighted in color.

Figure 3.

Differentially abundant taxa at family level from sow fecal content [ln change coefficients (2log) and FDR-adjusted P < 0.05] between d08 and d21 samplings. Only significant taxa with greater relative abundance than 0.05% are presented; positive and negative values indicate greater and lower abundance, respectively, in d21 animals; taxa are sorted by level of significance (from higher to lower).

Figure 4.

Differentially abundant taxa from fecal content (ln change and FDR-adjusted P < 0.05) on day 8 after farrowing between: BSU vs. CON, and BAM vs. CON at family (a) and genus (b) level. Only significant taxa with greater relative abundance than 0.05% are presented; positive and negative values indicate greater and lower abundance, respectively; the average relative abundance of each taxa is expressed in % below the family or genus name; taxa are sorted by level of significance (from higher to lower).

Figure 5.

NMDS of the relative abundances of ASV in piglet fecal content based on Bray–Curtis distance (stress = 0.169) during lactation (d21 of life) and after weaning (d33 of life and d12 after weaning). In order to facilitate the distinction between experimental treatments in (a), the same NMDS figure has been placed in parallel as (b) with the three diets highlighted in color.

Figure 6.

Differentially abundant taxa from fecal content (ln change and FDR-adjusted P < 0.05) between d21 and d33 samplings. Only significant taxa with greater relative abundance than 1.5% are presented; positive and negative values indicate greater and lower abundance, respectively, in d33 animals; the mean average relative abundance of each taxa is expressed in % between brackets; taxa are sorted by level of significance (from higher to lower).

Figure 7.

Differentially abundant taxa from fecal content (ln change and FDR-adjusted p < 0.05) of weaned piglets (d33) between: BSU vs. CON, and BAM vs. CON at family level. Only significant taxa with greater relative abundance than 0.05% are presented; positive and negative values indicate greater and lower abundance, respectively, in d33 animals; the mean average relative abundance (d33 only) of each family is expressed in % below the family name; taxa are sorted by level of significance (from higher to lower).

Figure 8.

Mean DCrt expression of all the genes analyzed sorted by dietary treatment. Genes have been grouped by function with different background colors. CON = Control; BSU = Bacillus subtilis; BAM = Bacillus amyloliquefaciens.