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.