Yan Zhiqun, Isobe Naoki, Kawakami Shin-Ichi
Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8528, Japan.
The Research Center for Animal Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8528, Japan.
J Poult Sci. 2020 Jul 25;57(3):236-240. doi: 10.2141/jpsa.0190109.
Testosterone (T) is known to induce aggressive behavior, particularly in male animals. However, our recent results showed that a certain kind of aggressive behavior is T-independent; moreover, the role of T in chicken territorial and isolation-induced aggressive behavior has not yet been investigated. In addition, castration alone is insufficient to evaluate the role of T in aggressive behavior because we found that non-testicular T concentration, probably derived from the adrenal gland, in the blood of castrated chicks was low, but not zero. In the present study, therefore, the role of testicular T in chicken aggressive behavior was evaluated through castration, and the role of nontesticular T was assessed using the subcutaneous implantation of flutamide, a non-steroidal antiandrogen, in the castrated male layer chicks. Resident-intruder (R-I) and social interaction (SI) tests were used to quantitatively monitor territorial and isolation-induced aggressive behavior, respectively. Castration and drug implantation of the chicks were performed at 14 days of age. The R-I test was performed at 29 and 30 days of age, and the SI test was performed at 31 and 32 days of age. The total aggression frequencies (TAFs) and aggression establishment rate (AER) were used as indices of chick aggressive behavior. In the R-I test, castration significantly decreased the TAFs but the AER was not affected by castration or flutamide implantation. In the SI test, on the other hand, there were no significant differences in the TAFs, but the AER tended to increase in the intact chicks and decrease in the flutamide-implanted, castrated male chicks. These results suggest that the role of T in chicken aggression depends on the differences in social context of the behavior, and that both testicular and non-testicular T play an important role in the occurrence of isolation-induced aggression in male layer chicks.
已知睾酮（T）会诱发攻击行为，尤其是在雄性动物中。然而，我们最近的研究结果表明，某种攻击行为与睾酮无关；此外，睾酮在鸡的领地性和隔离诱导攻击行为中的作用尚未得到研究。此外，仅通过阉割不足以评估睾酮在攻击行为中的作用，因为我们发现阉割雏鸡血液中可能源自肾上腺的非睾丸睾酮浓度较低，但不为零。因此，在本研究中，通过阉割评估睾丸睾酮在鸡攻击行为中的作用，并使用非甾体类抗雄激素氟他胺皮下植入阉割后的雄性蛋鸡来评估非睾丸睾酮的作用。分别使用定居者-入侵者（R-I）和社交互动（SI）测试来定量监测领地性和隔离诱导的攻击行为。雏鸡在14日龄时进行阉割和药物植入。R-I测试在29和30日龄时进行，SI测试在31和32日龄时进行。总攻击频率（TAFs）和攻击确立率（AER）用作雏鸡攻击行为的指标。在R-I测试中，阉割显著降低了TAFs，但AER不受阉割或氟他胺植入的影响。另一方面在SI测试中，TAFs没有显著差异，但完整雏鸡的AER有增加的趋势，而氟他胺植入的阉割雄性雏鸡的AER有下降的趋势。这些结果表明，睾酮在鸡攻击行为中的作用取决于行为社会背景的差异，并且睾丸和非睾丸睾酮在雄性蛋鸡隔离诱导攻击行为的发生中都起重要作用。
