Blood Testosterone Concentration and Testosterone-induced Aggressive Behavior in Male Layer Chicks: Comparison between Isolated- and Grouped-Raising.

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.