The Influence of Maternal Effects on the Response of Fast and Slow Growing Chickens to a Marek’s Disease Virus

Reciprocal cross F1 progeny from the Massachusetts High (MH) and Low (ML) Growth lines differed markedly in their response to inoculation at one day of age with the JM Marek’s disease (MD) virus. When the MH line was used as the female parent, the F1 progeny were both significantly heavier and more susceptible to MD at 8 weeks of age. A similar relationship between growth and MD susceptibility exists for the parent lines. Since growth rate is known to influence response to MD, the reciprocal crosses were compared at similar and reversed 8-week body weights by controlling feed intake for the heavier F1 group. At similar body weights the cross progeny of the MH dams were still more susceptible to MD infection. Therefore, the maternal effect associated with response to MD exposure is largely independent of the influence of body growth rate. The degree of dominance for susceptibility was also found to differ for the two groups of reciprocal cross progeny.