GENETICS OF GROWTH AND REPRODUCTION IN THE TURKEY .2. EVIDENCE OF NONADDITIVE GENETIC-VARIATION

A commercial sire line (C) and an experimental population selected solely for increased 16-wk BW (F) were reciprocally crossed to produce crossbred F1 and F2 progeny. The F1 and F2 crosses were used to evaluate the presence of nonadditive genetic variance for growth and reproductive traits. The crosses demonstrated improved growth performance as indicated by heterosis for 16- and 20-wk BW. The difference in BW was, however, reversed at maturity as indicated by negative heterosis for BW at maturity. The F1 and F2 crosses also exhibited heterosis for walking ability. Heterosis for reproductive traits was greater than for growth. The F1 crosses produced approximately 20 eggs more in a 180-day production season than the parental populations. This difference was halved in F2 generation hens. Improved egg production was achieved both through an increase in the rate of egg production and through a reduction in broodiness. The present experiment indicates that there is potential for significant heterosis for growth and reproduction in some crosses in the domestic turkey. The results also indicate that heterosis can be considerable, even in crosses of lines which do not differ greatly in BW or reproductive performance.