Effects of caponization and different exogenous androgen on the bone characteristics of male chickens.

The effects of caponization and androgen implantation on the bone characteristics of male chickens were evaluated. Healthy Single Comb White Leghorn cockerels were caponized or sham operated (sham) at 12 wk old. Sixteen birds from each group were selected for a 14-wk experiment in trial 1. Sixteen birds from the sham group and 64 from the caponized group (randomly allocated into 4 treatments) were implanted with 10.4 +/- 0.4 mg (1.62-mm i.d., 3.6-mm o.d.) of cholesterol, testosterone (TES), 5alpha-dihydrotestosterone (5alpha-DHT), or 19-nortestosterone (19-NorT) and were assigned to trial 2 for a 14-wk experiment. The results from trial 1 showed that caponization increased BW (P < 0.05) and decreased tibia stress, ash content, and P content with higher blood P concentration (P < 0.05) as compared with the sham group. In trial 2, the cholesterol implantation group showed the lowest tibia breaking strength, bending moment, stress, and ash content (P < 0.05). The 19-NorT implantation group showed decreased (P < 0.05) blood Ca and P concentration but increased tibia ash and P content, reaching the same level as the sham group (P > 0.05). The adverse effects of caponization on bone characteristics could be improved using androgen implantation. Among the implantation groups, the 19-NorT implantation group showed the best improvement in tibia breaking strength and bending moment, followed by the TES and 5alpha-DHT groups. The TES group showed the best improvement in tibia stress, followed by the 19-NorT and 5alpha-DHT groups.