Nestor K E, Bacon W L, Saif Y M, Renner P A
Poult Sci. 1985 Dec;64(12):2248-55. doi: 10.3382/ps.0642248.
Body weight and breast width have been greatly increased in the modern turkey. However, the relative amounts of leg muscles and leg bones have declined. A similar decline also occurs with age. It was theorized that this is an inherent weakness that magnifies other causes of leg problems. In an attempt to increase the relative amount of leg bone, a subline (FL) was developed by mass selection for increased shank width at 16 weeks of age from a long-term growth-selected line of turkeys (F). Shank width of FL was increased greatly by selection. The realized heritability of shank width, based on the regression of accumulated selection response on accumulated selection differential, was .33 +/- .05 over five generations of selection. Body weight of males from FL increased at a rate comparable to that of F at 16 weeks of age. However, there was no comparable improvement in body weight of FL females, resulting in a significant line X sex interaction. A similar interaction was observed for body weight at 8 and 20 weeks of age in these lines. The genetic increases in shank width in FL resulted in significantly improved walking ability of males at 16 weeks of age in comparison to F, even though body weight of males from the two lines was similar. The walking ability of FL did not change relative to the control line from which F originated. Thus, large genetic increases in body weight of males can be achieved without loss in walking ability by genetic increases in shank width.(ABSTRACT TRUNCATED AT 250 WORDS)
现代火鸡的体重和胸宽大幅增加。然而，腿部肌肉和腿骨的相对比例却下降了。随着年龄增长，类似的下降情况也会出现。据推测，这是一种内在弱点，会放大导致腿部问题的其他因素。为了增加腿骨的相对比例，从一个长期经过生长选育的火鸡品系（F）中，通过对16周龄时胫宽增加进行群体选择，培育出了一个亚系（FL）。通过选择，FL的胫宽大幅增加。基于累积选择反应对累积选择差的回归，胫宽的实现遗传力在五代选择中为0.33±0.05。FL雄性在16周龄时体重增加速度与F相当。然而，FL雌性的体重没有类似的改善，导致显著的品系×性别互作。在这些品系中，8周龄和20周龄时的体重也观察到类似的互作。FL胫宽的遗传增加导致16周龄雄性的行走能力相比F显著提高，尽管两个品系雄性的体重相似。FL的行走能力相对于F所源自的对照品系没有变化。因此，通过增加胫宽的遗传改良，可以在不损失行走能力的情况下实现雄性体重的大幅遗传增加。（摘要截短至250字）
