Parental effect on the humoral immune response to Escherichia coli and Newcastle disease virus in young broiler chicks.

Genetic and environmental variables influence animal resistance to disease infection. In addition, maternal effects were also found in studies with egg-type chicken lines. In our laboratory, meat-type chicken lines were divergently selected for either early or late maturation of the immune system, based on family and individual antibody responsiveness at 10 d of age. The high-antibody (HC) and low-antibody (LC) lines differed significantly in the early immune response to Escherichia coli, to Newcastle disease virus (NDV) vaccination, and to several other immune functions. Reciprocal crosses between the HC and LC lines were performed over 2 yr at three different locations. Immune responses to E. coli and NDV vaccination provided separate estimates of maternal and paternal effects. Dam effect on immune response to E. coli vaccine was significantly larger than sire effect; the antibody titer in both reciprocal crosses was intermediate between the parental lines, but the mean titer of the HC x LC cross was significantly lower than that of the LC x HC cross. Similar, but not significant, ranking of crosses was observed for the response to NDV. Evidently, the level of the offspring humoral immune response was more a dam than a sire effect.