Effects of caponization on growth, carcass, and meat characteristics and the mRNA expression of genes related to lipid metabolism in roosters of a Chinese indigenous breed

The effects of caponization on growth, body measurements, carcass traits, meat quality, and the mRNA expression of three genes related to lipid metabolism in Guang-xi Yellow roosters were evaluated. Thirty roosters (25 days) of similar weight were randomly divided equally into the experimental (capons, n = 15) and control (intact males, n = 15) groups. Caponization was conducted at 28 days of age, and birds were slaughtered at 140 days of age. Capons were significantly heavier (P < 0.05) than intact males and also had longer keel length and chest depth (P < 0.05 or P < 0.01). There were no significant differences in the percentage of eviscerated weight with giblet and eviscerated weight between the two groups. However, caponization increased breast muscle yield and decreased leg muscle yield (P < 0.05). The capons exhibited higher lightness values for thigh meat and lower redness values for both breast and thigh meat. Moreover, caponization up-regulated the fatty acid synthase (FAS) mRNA level in the liver, indicating enhanced hepatic lipogenesis, and also up-regulated the lipoprotein lipase (LPL) and peroxisome proliferator-activated receptor γ (PPARγ) mRNA levels in abdominal adipose tissue, which indicates increased lipid deposition and adipocyte differentiation. Therefore, caponization is associated with heavier body weight, higher breast meat yield, and higher abdominal fat percentage in Guang-xi Yellow roosters; the higher abdominal fat percentage may be associated with the increase in the mRNA expression of FAS, LPL, and PPARγ.