Effect of Saccharomyces cerevisiae yeast products in reducing direct colonization and horizontal transmission of Salmonella Heidelberg in broilers

Abstract

This study was conducted to evaluate the effectiveness of different levels of Saccharomyces cerevisiae yeast cell wall or a yeast culture in reducing the direct colonization and horizontal transmission of Salmonella Heidelberg in broiler chickens. At d of hatch, 2,000 male broiler chicks were randomly assigned into 5 treatment groups with 8 replicate pens per treatment. Birds were challenged with nalidixic acid-resistant S. Heidelberg either by direct inoculation of 107 cfu orally (seeders) or by horizontal transmission through inoculated penmates (contacts). Yeast cell wall (YCW) at 500 ppm decreased salmonella prevalence of the total infected birds (seeders and contacts) to 41.7% as compared to 54.2% in the untreated birds. The effect of YCW in reducing prevalence of positive birds was even greater when we considered the contact birds only; 32.5% in contact birds treated with 500 ppm as compared to 57.5% in the untreated group (P = 0.09). Furthermore, enumeration of S. Heidelberg colonization level in the cecum using the most probable number (MPN) method showed that YCW at 500 ppm reduced the bacterial load in the cecum of positive birds to 1.7 MPN/g as compared to 2.7 MPN/g in the control group. The reduction was statistically significant (P = 0.04) in the contact birds. The same effect was not seen in the yeast culture treatment.