K. E. Nestor 1
J. W. Anderson
The Ohio State University Department of Animal Sciences
Published research indicated that a line (FL) of turkeys selected for increased shank width and exhibiting good walking ability (WA) and improved leg structure was useful in improving WA of a cross with an unimproved commercial sire line while remaining competitive in body weight (BW) and body conformation. The purpose of the present study was to determine if the FL line was useful in improving WA of two improved commercial primary-breeding sire lines and to study the inheritance of BW traits in the pure lines and reciprocal crosses of the pure lines. Samples of a primary breeding sire line from each of two major commercial turkey breeders was obtained as unpedigreed eggs and designated as Lines A and B. Lines A and B were reciprocally crossed with the FL line that had been selected for increased shank width for 16 generations. Pure lines and reciprocal crosses were produced by artificially mating 10 males to 15 females using pooled semen. The same semen pools were used to produce the pure lines as to produce the crosses. Traits measured included BW at 8, 16, and 20 weeks of age, and length, width, and depth of the shank, width of the breasts, and WA at 16 weeks of age. The A and B lines were larger, had wider breasts, and narrower and shorter shanks than the FL line. Line B was larger than Line A. Shank measurements and WA score did not differ between Lines A and B in either sex. Breasts of Line B females were wider than those of Line A females but there was no male line difference in breast width of males. Heterosis in BW was larger in Line A crosses (average of 4.6% with a range of 2.5 to 7.2% for BW at different ages) than in Line B crosses (average of 2.2% with a range of 0.1 to 5.3%). Heterosis in WA scores was negative (crosses had better WA than pure lines) for males [14% for the Line A and FL crosses (P < 0.001) and 4% for the Line B and FL crosses (P 30.05)] but was positive and nonsignificant for females of these crosses (average of 2.6%). With one exception, heterosis was not an important source of variation for shank width or shank depth, and there was a low level of heterosis for shank width. No heterosis was observed for breast width. Reciprocal effects were an important source of variation in BW and shank measurements for females but not for males in both sets of crosses. The results of the present study indicated that use of the FL line to improve WA of improved primary-breeding commercial sire lines was not a feasible alternative. The slight improvement noted in WA of the male crosses was offset by the reduction in BW and breast width of the crosses relative to the pure commercial sire lines.
1For more information, contact at The Ohio State University, Ohio Agricultural Research and Development Center, 125 Gerlaugh Hall, 1680 Madison Avenue, Wooster, OH 44691; 330-263-3757; fax: 330-262-3949; e-mail: nestor.1@osu.edu