Department of Poultry Science, University of Georgia, 30602, Athens, GA, USA.
Theor Appl Genet. 1984 Nov;69(1):15-21. doi: 10.1007/BF00262530.
Five experiments were conducted to assess the genetic variation in thyroid function (T3, T4), body weight and heat stress survival time in chickens. Thyroxine (T4) levels were found to be elevated in response to 4 and 8 μg bovine thyroid stimulating hormone (TSH) in experiment I. In experiment II, 4 μg of TSH was injected into chickens from 30 sire families of the Athens-Canadian Randombred population. The heritability of T4 levels after TSH injection was high. In experiment III, families identified as having innate high or low T4 levels after TSH injection and a group of control birds were subjected to a heat Stressor of 50 °C for up to 240 min at six weeks of age and heat stress survival time was studied. The groups did not differ from each other in heat stress survival time. Experiment IV was similar to experiment I except triiodothyronine (T3) was also measured after TSH injection. Both T4 and T3 levels after TSH injection were moderately heritable. In experiment V birds were reared to six weeks of age and heritability calculated for body weight, T4, T3, and heat stress survival time. Heritabilities were high for body weight, moderate for T4 and heat stress survival time, and low for T3. Phenotypic correlations were significant and negative for heat stress survival time with body weight and T4, and for body weight with T3 after TSH. Significant positive correlations were found for T4 with T3 after TSH and also T4 and body weight. Analysis of genetic correlations suggested that none of the traits studied would be an adequate selection parameter for achieving heat tolerance without reducing body weight.
进行了五项实验来评估鸡的甲状腺功能（T3、T4）、体重和耐热生存时间的遗传变异。在实验 I 中，发现甲状腺素（T4）水平在 4 和 8 μg 牛促甲状腺激素（TSH）的刺激下升高。在实验 II 中，从雅典-加拿大随机杂种群体的 30 个 sire 家族中向鸡注射 4 μg 的 TSH。TSH 注射后 T4 水平的遗传力很高。在实验 III 中，鉴定出在 TSH 注射后具有先天高或低 T4 水平的家族和一组对照鸟在六周龄时受到 50°C 的热应激源的影响，并研究了耐热生存时间。各组在耐热生存时间上没有差异。实验 IV 与实验 I 相似，只是在 TSH 注射后还测量了三碘甲状腺原氨酸（T3）。TSH 注射后 T4 和 T3 水平均具有中度遗传力。在实验 V 中，鸡被饲养到六周龄，并计算体重、T4、T3 和耐热生存时间的遗传力。体重的遗传力较高，T4 和耐热生存时间的遗传力中等，T3 的遗传力较低。表型相关性在耐热生存时间与体重和 T4 之间以及 TSH 后体重与 T3 之间呈显著负相关。在 TSH 后 T4 与 T3 之间以及 T4 与体重之间发现了显著的正相关。遗传相关分析表明，在不降低体重的情况下，研究的性状中没有一个可以作为耐热性的适当选择参数。
