Molting increases susceptibility to Salmonella enteritidis infection by how much?

• A. 2 to 5 times
• B. 10 times less susceptible
• C. No change
• D. 100 to 1,000 times more susceptible

Answer: (D)

Molting creates a window of vulnerability by weakening the bird’s defenses at multiple levels. The feather-replacement process is stressful and redirects energy toward growth, which suppresses immune function and damages gut defenses. Stress hormones rise and lymphoid tissues shrink, dampening both cell-mediated and humoral immunity. The gut barrier also becomes less robust, and nutrient intake may decline during molt, further compromising the bird’s ability to resist pathogens. Salmonella enteritidis can capitalize on this weakened state, leading to a much higher chance of infection and persistence than during non-molting periods. This is why the increase in susceptibility is described as very large, making it the best choice compared with the other options that imply little, no, or even reduced susceptibility.