Effect of induced molting on the course of infection and transmission of Salmonella enteritidis in white Leghorn hens of different ages.

Previous work in the authors' laboratory had shown that inducing molt using a 2-wk feed removal protocol in 58- to 84-wk-old White Leghorn hens increased the severity of intestinal infection by Salmonella enteritidis (SE). As susceptibility to infection can be influenced by age, a study was conducted to compare the effect of the feed removal on infection by SE in 20-, 40-, and 74-wk-old hens. Birds were orally infected with 5 to 10 x 10(6) SE on Day 4 of fast and were sampled for SE shedding 3, 10, 17, and 24 days later. Significantly higher numbers of SE were shed in fasted birds on Day 3 (20 and 40 wk of age), Day 10 (40 and 74 wk of age), and Day 17 (74 wk of age). Transmission of SE to uninfected, contact-exposed birds was observed in all three trials for both the fed and fasted groups. However, significantly more fasted contact-exposed birds became positive for SE on Day 3 (20-wk-old), Day 10 (74-wk-old), and Day 17 (74-wk-old). Significantly more SE was also shed in these fasted contact-exposed birds on Day 3 (20-wk-old), Day 10 (all age groups), and Day 17 (74-wk-old). The current results indicate that the fasting conditions used to induce a molt in hens increase the shedding of SE in direct-infected and contact-exposed hens and this effect does not appear to be affected by age.