Maternal laminarin supplementation decreases Salmonella Typhimurium shedding and improves intestinal health in piglets following an experimental challenge with S. Typhimurium post-weaning

During the period immediate post-weaning (PW), piglets become vulnerable to pathogenic bacteria such as Salmonella Typhimurium, the most common Salmonella serovar. Laminarin (LAM), a β-glucan derived from seaweed, is known to have antimicrobial and anti-inflammatory activity when supplemented maternally or directly to the piglet. The aim of this study was to investigate the effects of supplementing sows and/or piglets post-weaning with LAM after an experimental challenge with S. Typhimurium. Gestating sows (n = 24) were supplemented with LAM (0 vs. 1.0 g/d) from day 107 of gestation until weaning (day 20). The lactation and PW diet were arranged in a 2 × 2 factorial to provide four treatment groups: (1) pigs weaned from basal fed sows and offered a basal diet post-weaning (n = 12; BB); (2) pigs weaned from basal fed sows and offered a LAM supplemented diet post-weaning (n = 12; BL); (3) pigs weaned from LAM supplemented sows and offered a basal diet post-weaning (n = 12; LB); (4) pigs weaned from LAM supplemented sows and offered a LAM supplemented diet post-weaning (n = 12; LL). The LAM supplemented post-weaning diets contained 300 ppm LAM/t of feed. On day 10 PW, piglets were challenged with 108 CFU S. Typhimurium and euthanized on day 26 PW to facilitate sample collection for microbial populations, volatile fatty acid (VFA) and immune related gene expression analysis. Pigs were weighed at birth, at weaning, at challenge and at slaughter and feed intake post-weaning was recorded. Faeces were visually scored for diarrhoea. Piglets weaned from LAM supplemented sows had improved average daily gain (ADG) and feed efficiency post-challenge (P < 0.05). The faecal score was improved when LAM was supplemented maternally or post-weaning (P < 0.001). Maternal supplementation of LAM reduced faecal counts of S. Typhimurium by 0.35 log gene copy numbers post-challenge (measured on day 2, 5 and 7; P < 0.05). Total VFA production in the colon was increased after maternal or post-weaning LAM supplementation (P < 0.05). The expression of IL-22 in the colon was reduced after maternal LAM supplementation (P < 0.05). It can be concluded that, after an experimental challenge with S. Typhimurium, maternal LAM supplementation resulted in improved feed efficiency, faecal scores and increased the VFA production in the colon, while reducing faecal counts of S. Typhimurium and gene expression of IL-22 in the colon.