Effect of induced molting on the susceptibility of White Leghorn hens to a Salmonella enteritidis infection.

Older white leghorn hens (more than 52 weeks old) were induced to molt using a 14-day feed-removal protocol. On day 4 of feed removal, groups of hens were infected with varying 10-fold dilutions of Salmonella enteritidis, and these hens were examined for S. enteritidis intestinal shedding 7 days later. Molting hens infected with a 10(-2) dilution of S. enteritidis shed 3-4 logs more of the organism at 7 days postinfection than the unmolted group receiving a similar dose. The mean infectious dose (ID50) for S. enteritidis in unmolted hens ranged from 0.65 x 10(4) to 5.6 x 10(4), whereas in molting hens the ID50 was found to be less than 10(1), a 2-3 log increase in the susceptibility of the hens to the organism.