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.