EFFECT OF SALMONELLA IN YOUNG CHICKS ON COMPETITIVE-EXCLUSION TREATMENT

The potential of Salmonella contamination in hatching cabinets to 1) g enerate seeder chicks and 2) interfere with the efficacy of competitiv e exclusion (CE) treatments was investigated in six experiments. Hatch ery-generated seeder chicks were produced by hatching in the same hatc her with inoculated eggs (immersed in a 1.0 x 10(5) cfu/ml suspension of Salmonella typhimurium or inoculated with 10(5) to 10(6) cells on t he air cell membrane). Salmonella spread through the hatching cabinet to chicks hatching from uninoculated eggs in adjacent trays. In two ex periments, Salmonella was isolated from 31 and 100% of the chick rinse s after the birds were held in groups for 3 d in isolation units. When these hatchery-generated seeder chicks were stocked in floor pens at a 1:10 ratio with uncontaminated contact chicks, the pen environment b ecame contaminated to the extent that greater than 50% of the contact chicks became contaminated. In two experiments with only one to three inoculated eggs per 200 egg hatching cabinet, 98% of uninoculated chic ks were intestinally colonized with Salmonella after the birds were he ld 1 wk in isolation cabinets. This hatchery-acquired Salmonella subst antially reduced the effectiveness of subsequent CE treatments to prev ent Salmonella colonization of the young chicks. These studies demonst rate that control of Salmonella in hatching cabinets is critically imp ortant for control of Salmonella in broilers.