Prevalence of Salmonella enteritidis and Other Serovars in Ovaries of Layer Hens at Time of Slaughter

Abstract

Ovaries aseptically collected from commercial layer hens at time of slaughter were assayed for Salmonella as an indication of systemic infection of birds within a flock. Birds were randomly selected at the time of slaughter from 42 flocks from seven southeastern states and Pennsylvania. Ovaries were pooled, four per pool, mascerated, and Salmonella, isolates were recovered by conventional methods. Thirty-two of 42 flocks (76.2%) were positive at >10% infection rate based on sampling methods. Fifteen different serovars were detected in flocks. Salmonella heidelberg was the predominant serovar, representing 56.5% of the salmonellae detected. However, S. agona, S. oranienburg, S. mbandaka, S. kentucky, S. montevideo, S. london, S. typhimurium, S. infantis, S. schwarzenqrund, S. ohio, S. cerro, S. anatum, and Salmonella untypeable were also found. S. enteritidis, phage type 23 was recovered from only one (2.4%) of the flocks. Single and multiple serovar infections were found with up to five serovars recovered from a single flock. Twenty-one positive flocks (50%) were positive with a single Salmonella serovar; of these S. heidelberg represented 76.2%. An overall mean of 26.6% of the pooled ovary samples within each infected flock was positive for salmonellae, with an overall range of 0–100%. The significance of Salmonella serovars other than S. enteritidis found at the levels reported has yet to be determined.