Differences in carbohydrate composition of barley varieties influence Salmonella transmission among pen mate weaned piglets

Indigestible carbohydrate (CHO) composition can vary markedly between barley varieties. They induce changes in intestinal ecophysiology and enhance growth of health-promoting bacteria. An experiment was undertaken to assess whether these changes could influence Salmonella typhimurium (ST) infection in pigs and transmission between penmates. A challenge study was undertaken using 84 recently weaned piglets divided in 12 pens, and fed one of the 4 experimental diets (3 pens/diet), according to the barley variety. Three hullless and one hulled varieties were chosen according to their differing CHO composition (amylose/amylopectin, β-glucan, and insoluble non-starch polysaccharides). After 14 d of adaptation, 2 pigs per pen (Trojan pigs, TrojP) were orally infected (8.0 log cfu/animal) with a low virulent, nalidixic acid and novobiocin resistant ST strain. The other animals were considered as Contact pigs (ConP) to assess ST transmission. Over 5 d following inoculation, pigs were monitored for detection of ST in the feces using plate counts. On d 6, 2 TrojP and 2 ConP per group were killed and intestinal samples as well as organ samples (liver, spleen, and lymph nodes) were analyzed for ST. The results showed that in TrojP, the cereal variety had no influence on ST fecal shedding over time and gastrointestinal tract (GIT) colonization. All pigs were positively tested for ST. Translocation of ST to lymph nodes was observed frequently but not to other organs. In ConP, compared with hulled barley, hulless barleys reduced the number of animals shedding ST (P < 0.05 for d 2) and the number of ST (cfu/g) in cecum on d 6 (P < 0.01). Although hulless barleys did not protect against colonization when directly challenged at a high oral dose, these barleys may be useful to reduce natural ST transmission among penmates