Correlated responses of chickens to selection for production of antibodies to sheep erythrocytes.

A bidirectional selection experiment was conducted to measure 5-day antibody titers to sheep erythrocytes in White Leghorn chickens. There was an immediate response to selection with significant differences between lines for the selected trait found in the S1 and all subsequent generations. Comparisons of S6, S7 and S8 generation females revealed differences between lines in disease resistance and in certain reproductive traits such as age at first egg, percentage hen-day egg production, percentage fertility and duration of fertility. The implications of these correlated responses are important to selection programs for general disease resistance.