Comparison of Salmonella enteritidis infection in hens molted via long-term feed withdrawal versus full-fed wheat middling

Molting is an important economic management tool for the layer industry as a means of maximizing the effective laying life of a flock. Previous work has shown that molting birds through feed removal (FM) increased the severity of a Salmonella Enteritidis (SE) infection. The current study was conducted to follow the progression of an SE infection in unmolted hens versus hens molted via 14-day FM or ad libitum feeding of wheat middlings (WM), in the presence or absence of 2.5% lactose administered in the drinking water. In two trials of the experiment, all hens were infected with approximately 1 x 10(7) SE at day 4 of molt and sampled for SE shedding on days 4, 10, 17, and 24. postinfection (PI). Organ levels of SE were determined on day 7 PI. All molt procedures caused cessation of egg lay within 3 to 7 days. In trials 1 and 2, birds subjected to total FM shed 3 to 5 logs more SE than either the control birds (unmolted) or the birds fed WM on days 4 and 10 PI. Liver and spleen, ovary, and cecum counts were also significantly (P < 0.05) higher in the fasted birds in one trial and liver and spleen and cecum counts in the second. No differences in any of the SE counts were observed in unmolted versus WM-fed birds. Lactose supplementation in drinking water did not provide any advantage in reducing SE infection in either trial. These results indicate that there are alternative methods to long-term FM that can be used to molt birds and not increase the risk for SE problems. How these alternative methods compare with FM with regard to second-cycle egg production and the mechanisms involved in the reduced SE shedding remain to be investigated.