Effects of caponization and age on the histology, lipid localization and fibre diameter in muscles of Rhode Island Red cockerels

Poultry scientists are constantly studying different breeds of cockerels that would be suitable for capon meat production. Capon meat, although not yet very popular, is characterized by exceptional taste qualities that could appeal to many customers. Obtaining the appropriate palatability, structure and tenderness of capon meat is possible thanks to the reduction in androgen levels following the castration of roosters. Surgical or chemical castration affects the metabolism of fats, thus increasing their accumulation in the abdominal cavity, subcutaneous tissue and muscles. The main aim of our research was histological evaluation and analysis of the concentration and distribution of adipose tissue in muscles in Rhode Island Red cockerels and capons. In addition, we analysed the diameter of the pectoral muscle fibre. The experiment was performed on 200 Rhode Island Red cockerels; the testes were removed at 8 weeks of age. At 12, 16, 20, 24 and 28 weeks of age, 6 cockerels and 6 capons were slaughtered, and samples from the pectoral and thigh muscles were evaluated. Differences in the accumulation of adipose tissue with muscular atrophy (p<0.05) were observed in thigh muscles, with higher amounts in capons than in cockerels. All examined locations in the pectoral and thigh muscles of capons (around the blood vessels, in the perimysium, in the endomysium, and in the sarcoplasm) showed much higher concentrations of lipids compared to the levels in cockerels. The diameters of the pectoral muscle fibres were different (p<0.05) at 12 and 16 weeks of age, and the diameters of the giant fibres were different (p<0.05) at 12 and 20 weeks of age, with higher values in cockerels. The high concentration of lipids in the skeletal muscles of Rhode Island Red capons is impressive. These dual-purpose cockerel breeds can be a source of high-quality meat.