Effect of caponization and exogenous androgens implantation on blood lipid and lipoprotein profile in male chickens

This study investigated effects of caponization and different forms of androgen implantation on blood lipid and lipoprotein profile of capons to understand the role of different androgens. Male chickens were caponized at 12 wk of age and selected at 16 wk of age for a 10-wk feeding period. Sixteen intact caponized (capon) male chickens and 16 female chickens were assigned for trial 1, and 16 sham-operated (sham) male chickens and 64 capons were selected for trial 2, in which capons were randomly divided into cholesterol (CHOL), testosterone (TES), 5alpha-dihydrotestosterone, or 19-nortestosterone (19-NorT) implantation at 16, 20, and 24 wk of age. Trial 1 showed that caponization decreased TES concentration (P < 0.05) in male chickens while showing no difference with females (P > 0.05). Caponization increased lipoprotein lipase (LPL) activity and relative abdominal fat weight (P < 0.05) to a level compatible with females (P > 0.05). Caponization also increased low-density lipoprotein (LDL) content and LDL-protein percentage (P < 0.05) but decreased high-density lipoprotein-free CHOL percentage (P < 0.05) compared with intact males. In trial 2, androgen implantation showed lower relative abdominal fat weight (P < 0.05) than CHOL. Only 19-NorT reached a level compatible with the sham (P > 0.05). Cholesterol implantation increased LPL activity compared with the sham (P < 0.05), and 19-NorT and 5alpha-dihydrotestosterone showed the lowest LPL activity (P < 0.05). Different androgen implantations increased LDL and very low density lipoprotein + LDL ratios and decreased high-density lipoprotein ratio (P < 0.05) to the compatible level with the sham (P > 0.05). Different levels of androgen implantation also demonstrated changes in LDL triacylglyceride and protein percentage and reached a level compatible with the sham (P > 0.05). Caponization decreased blood TES concentration in male chickens, increased LPL activity, and changed the lipoprotein composition, leading to an increase in abdominal fat weight. Results of different androgen implantations in capons demonstrated no difference in lipoprotein profile between androgens, but 19-NorT performed most effectively in abdominal fat accumulation recovery.