Strategies to Reduce Colonization of Salmonella Enteritidis in Layers

Salmonella Enteritidis is a significant foodborne pathogen that can often be traced back to poultry and poultry products. Feed ingredients such as Bacillus probiotics and parietal yeast fractions have gained in interest to reduce food safety issues. Consequently, 2 in vivo trials were setup to evaluate the ability of these products to reduce Salmonella Enteritidis colonization in the laying pullets and hens. In the first trial, 60 Hy-Line Brown pullets aged 9 weeks were randomly distributed to individual cages in 15 replicate blocks of 4 pens. The treatments were control, 500g/ton yeast parietal fraction, 500g/ton Bacillus spp probiotic and 1kg/ton yeast culture. On day 3 of the trial all birds were orally administered 3x107 CFU of a nalidixic acid resistant Salmonella Enteritidis. On day 10, seven days after inoculation all birds were humanely euthanized, and the ceca aseptically removed for CFU determination. In the 2nd trial, 60 Hy-Line hens aged 56 weeks were placed in individual cages and fed a mash diet containing one of the following treatments, control, 500g/ton Bacillus spp. probiotic, 500g/ton yeast parietal fraction or a combination of yeast parietal fraction and Bacillus spp. probiotic. At 60 weeks of age all hens were challenged orally with 7 x 10⁷ CFU/bird of Salmonella Enteritidis. At 61 weeks of age, birds were humanely euthanized, and the ceca aseptically removed and cultured for Salmonella Enteritidis prevalence and number by the Most Probable Number (MPN) method. Results of the first trial show that the mean quantity of Salmonella Enteritidis detected in the ceca expressed in log10 MPN/g was 2.52 in the control, 2.49 in the yeast parietal fraction treatment, 1.73 in the probiotic treatment, and 1.66 in the yeast culture treatment. In the second study, the control birds had 3.35 log10 MPN/g of Salmonella Enteritidis in the ceca. The Probiotic group had 1.90 MPN/g, a reduction of 1.44 (p<0.05) and the yeast cell wall group had 1.84MPN/g a reduction of 1.51 (p<0.05). The combination had 2.56 MPN/g a numerical reduction of 0.79 (p=0.14). These studies demonstrate the ability of Bacillus spp. probiotic and the yeast parietal fractions or cultures to reduce the load of Salmonella Enteritidis in layer ceca.

Key Words: Salmonella, Layer, probiotic, yeast, feed