Novel probiotics Lactobacillus paracasei and Lactobacillus rhamnosus inhibit Salmonella colonization in layers and prevent egg-borne transmission

Abstract

Salmonella

Enteritidis (SE)-contaminated eggs are a major cause of foodborne outbreaks in the U.S. Contamination can occur through horizontal transmission from the environment or vertical transmission from SE-colonized layers, affecting the outer shell (OS), inner shell (IS), and internal contents (IC), leading to outbreaks. Hence, there is need for effective pre-harvest solutions to control SE on eggs. Here we evaluated the efficacy of two novel probiotics, i) Lactobacillus rhamnosus NRRL-B-442 (LR) and Lactobacillus paracasei DUP 13076 (LP) as in-feed supplements to reduce SE colonization in layers and prevent egg-borne transmission. For this study 19- and 40-week-old birds were assigned to 4 treatments with replicate pens of 10 birds each. Treatments included layer diet without probiotics (control) and diet supplemented with 9 log CFU/kg of LP, LR, or the cocktail (PR). Birds were challenged with SE (10 log CFU/bird) by crop gavage and eggs tested daily for SE for 5 weeks. In-feed supplementation of probiotics reduced SE load by ∼0.8 log CFU/g in the cecum and to below detection limits in the oviduct. Further, in 19-week-old birds, approximately 45 % of eggs in the probiotic groups were SE-positive in the outer shell (OS) compared to 84 % in the control. Additionally, only 10–15 % of internal content (IC) samples tested SE-positive in the probiotic groups, while over 50 % were SE-positive in the control. Similar results were observed with birds in peak lay (40-week-old birds). Overall, in-feed supplementation of probiotics significantly reduced egg-borne transmission of SE thereby improving egg safety.