Christensen V L
Poult Sci. 1985 Nov;64(11):2202-10. doi: 10.3382/ps.0642202.
Fertile turkey eggs were injected with thyroid hormones to test the effects of exogenous hormones on hatchability. Physiological doses of thyroxine (T4) and triiodothyronine (T3) of 50 and 25 ng, respectively, injected at setting, depressed hatchability. Conversely, injections of T4 and T3 at 25 days of incubation significantly (P less than .05) improved hatchability. Injections with thyroid-stimulating hormone (TSH) or tyrosine had no significant effect on hatchability when injected at setting or at 25 days of incubation. Injections of thyroid-releasing hormone (TRH) had no effect on hatchability when injected at setting but significantly (P less than .05) improved hatchability when injected at 25 days of incubation. Because T4 and T3 significantly (P less than .05) depressed hatchability when injected whereas TSH and TRH had no effect on hatchability when injected at setting, these data suggest classic negative feedback mechanisms function very early in the embryonic turkey. The improvement in hatchability observed when thyroid hormones were injected at 25 days of incubation offers further evidence that hypothyroidism may be a cause of poor hatchability among turkey eggs.
将可育火鸡卵注射甲状腺激素，以测试外源激素对孵化率的影响。在孵化开始时分别注射生理剂量的50纳克甲状腺素（T4）和25纳克三碘甲状腺原氨酸（T3），会降低孵化率。相反，在孵化25天时注射T4和T3能显著（P小于0.05）提高孵化率。在孵化开始时或孵化25天时注射促甲状腺激素（TSH）或酪氨酸，对孵化率没有显著影响。在孵化开始时注射促甲状腺激素释放激素（TRH）对孵化率没有影响，但在孵化25天时注射则显著（P小于0.05）提高了孵化率。由于注射时T4和T3显著（P小于0.05）降低了孵化率，而在孵化开始时注射TSH和TRH对孵化率没有影响，这些数据表明经典的负反馈机制在火鸡胚胎发育早期就发挥作用。在孵化25天时注射甲状腺激素时观察到的孵化率提高，进一步证明甲状腺功能减退可能是火鸡卵孵化率低的一个原因。
