Yan Zhiqun, Kamiguri Naomasa, Isobe Naoki, Kawakami Shin-Ichi
Graduate School of Biosphere Science, 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. 2019 Oct 25;56(4):290-297. doi: 10.2141/jpsa.0180135.
Testosterone (T) is known to induce aggressive behavior, mainly in male animals. Subcutaneous implantation of T-filled silastic tubes, rather than intramuscular injection of T, is generally recommended for long-term treatment using exogenous T. However, the effect of T implantation on chicken aggressive behavior has not been investigated. In addition, the concentration of T required to induce aggressive behavior or whether rearing conditions such as isolated- or grouped-raising affect T-induced aggressive behavior in chickens is not known. The present study aimed to examine the relationship between the lengths of T-filled tubes, blood T concentration, and aggressive behavior in group- and isolation-raised male layer chicks. The testes were bilaterally removed and silactic tubes of various lengths filled with crystalline T were subcutaneously implanted at 14 days of age. A social interaction test was performed to quantitatively assess chick aggressive behavior at 32 days of age. Comb weight and size were used to assess the activation of endogenous androgen receptors. Total aggression frequencies (TAF) and aggression establishment rate (AER) were used to evaluate aggressiveness. Significant positive correlations (<0.001) were observed between the comb parameters and plasma T concentration. In the isolation-raised chicks, the TAF and AER were high irrespective of the lengths of the implanted T tubes or the corresponding plasma T concentrations. However, in the group-raised chicks, the AER tended to differ between the T-implanted aggressors (=0.0902), and the AER significantly increased with implantation of 1.0-cm-long T-filled tubes (<0.05), which corresponded to approximately 47 pg/mL plasma T concentration. These results suggest that both grouped raising and approximately 47 pg/mL plasma T concentration are required for the induction of T-dependent aggressive behavior, and that isolation-induced aggressive behavior is T-independent in male layer chicks.
已知睾酮（T）会诱发攻击行为，主要发生在雄性动物身上。对于使用外源性睾酮进行长期治疗，一般建议皮下植入填充睾酮的硅橡胶管，而非肌肉注射睾酮。然而，睾酮植入对鸡攻击行为的影响尚未得到研究。此外，诱发攻击行为所需的睾酮浓度，或者诸如单独饲养或群体饲养等饲养条件是否会影响鸡的睾酮诱发攻击行为，目前尚不清楚。本研究旨在探讨在群体饲养和单独饲养的雄性蛋鸡雏鸡中，填充睾酮的管长、血液睾酮浓度与攻击行为之间的关系。在14日龄时双侧摘除睾丸，并皮下植入不同长度、填充结晶睾酮的硅橡胶管。在32日龄时进行社交互动测试，以定量评估雏鸡的攻击行为。使用鸡冠重量和大小来评估内源性雄激素受体的激活情况。使用总攻击频率（TAF）和攻击确立率（AER）来评估攻击性。观察到鸡冠参数与血浆睾酮浓度之间存在显著正相关（<0.001）。在单独饲养的雏鸡中，无论植入的睾酮管长度或相应的血浆睾酮浓度如何，TAF和AER都很高。然而，在群体饲养的雏鸡中，植入睾酮的攻击者之间的AER存在差异（=0.0902），并且随着植入1.0厘米长的填充睾酮管，AER显著增加（<0.05），这对应于约47 pg/mL的血浆睾酮浓度。这些结果表明，群体饲养和约47 pg/mL的血浆睾酮浓度都是诱发睾酮依赖性攻击行为所必需的，并且在雄性蛋鸡雏鸡中，隔离诱发的攻击行为是睾酮非依赖性的。
