https://www.selleckchem.com/products/umi-77.html Total aggression frequencies (TAF) and aggression establishment rate (AER) were used to evaluate aggressiveness. Significant positive correlations (P less then 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 (P=0.0902), and the AER significantly increased with implantation of 1.0-cm-long T-filled tubes (P less then 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. 2019, Japan Poultry Science Association.Recently, we showed that oral administration of crystallized L-citrulline (L-Cit) caused hypothermia under a control thermoneutral temperature (CT) and provided thermotolerance under high ambient temperature (HT) in chicks. The aim of this study was to clarify whether oral administration of a medium containing L-Cit-producing live bacteria can reduce body temperature in chicks under CT. In Experiment 1, 7-day-old chicks were orally administered either a medium (containing mainly L-Cit-producing live bacteria and 277 mM L-Cit) or an equimolar amount of L-Cit to determine their effects on body temperature (acute treatment). In Experiment 2, chicks were subjected to the same treatment from 7 to 13 days of age (chronic treatment). Rectal and surface body temperatures were recorded daily after 1 h of treatment. Both acute and chronic oral administration of the medium, but not of the equimolar amount of L-Cit, significantly reduced the rectal and surface body temperatures of