Field and Laboratory Observations on Salmonella heidelberg Infection in Three Chicken Breeding Flocks

Abstract

Salmonella infection was detected in 3 breeding flocks of meat-strain chickens that manifested no visible signs of infection. A cloacal-swab culture method for the detection of paratyphoid infection in a flock appears to be more reliable than serum agglutination test for somatic antibodies. Salmonella was recovered from the environment of one farm during a 5-month sampling period. There was little correlation between a bird''s serological response and the recovery of S. heidelberg, either by cloacal culture or at necropsy. The organism was recovered from 80 birds cultured; only 11 of these birds were serologically positive. Salmonella was recovered from contaminated litter, grit, feed, and dust held for extended periods at room temperature; litter was positive at 18 months, when last tested. Infected birds contaminated a clean environment within several days. Eleven fecal ahedders of Salmonella became negative within several days after being placed in individual wire-floored cages in a clean environment. Salmonella were recovered from only a small percentage of eggs laid by infected hens.