Effect of wheat distillers dried grains with solubles or sugar beet pulp on prevalence of Salmonella enterica Typhimurium in weaned pigs

Abstract

Salmonella enterica Typhimurium (ST) is of concern in the swine industry with relevance for animal health and consumer safety. Nutritional strategies might help to reduce ST infection and transmission. This study examined the potential of wheat (Triticum aestivum) distillers dried grains with solubles (DDGS) and sugar beet (Beta vulgaris) pulp (SBP) to alter intestinal microbial communities and ST shedding using a Trojan model. Weaned pigs (n = 105; 28.5 ± 3.5 d of age) were separated into 3 treatment groups (7 pigs/pen) and fed a wheat-based control diet or the control diet formulated with 15% wheat DDGS or 6% SBP inclusion. Following 12 d of diet adaptation, 2 pigs/pen were inoculated with 2 x 109 cfu ST, resistant to novobiocin and nalidixic acid. Fecal swabs were taken from infected pigs and pen-mates (contact pigs) for 9 d following challenge, enriched in nutrient broth for 24 h, and plated on selective media to determine prevalence of ST. The ranges of prevalence of ST in feces were from 90 to 100% in challenged pigs and 74 to 78% in contact pigs. No influence of treatment on rectal temperature and prevalence of ST in contact pigs were observed. Fifteen contact pigs were euthanized per treatment group on 9 and 10 d postchallenge to enumerate in intestinal contents (ileum, cecum, and proximal colon), Lactobacillus spp., Enterobacteriaceae, and Clostridium clusters I, VI, and XVIa by quantitative PCR (qPCR) and to determine ST prevalence by selective culture. No significant effects of diet were observed with respect to ST prevalence in feces, ileum, cecum, colon, and lymph nodes of contact pigs. Compared with the control diet, DGGS and SBP diets showed a trend towards increased (P < 0.1) number of Lactobacillus species in the cecum and colon. Although both wheat DGGS and SBP tended to increase the Lactobacillus spp. neither of the feed ingredients affected ST prevalence.