Testicular growth and comb and wattles development in three Italian chicken genotypes reared under free range conditions

Abstract Male chickens belonging to three Italian purebreds – Ermellinata di Rovigo (ER), Robusta lionata (RL) and Robusta maculata (RM) – were studied. All the birds were reared under the same rearing conditions (from May until autumn). Chickens were reared under infra-red lamps from birth until 4 weeks of age with a 24L:0D photoperiod. Then they were kept outdoor: the photoperiod changed according to the season (from 16L:8D to 12L:12D). At 138 and 168 days of age 20 birds/breed were weighed and then slaughtered. Testicular samples were collected, after evisceration, processed and embedded in paraffine wax. Sections were stained for morphological observations, observed with light microscope, and then classified according to the testis maturation stage. Ermellinata di Rovigo chickens showed the lowest (P<0.01) body weight and the highest (P<0.01) testes weight; testes maturity was higher (P<0.01) in ER than in RL, whereas RM was intermediate. For each genotype testes weight and testes maturity did not significantly differ with aging. Correlations between testes weight and body, comb, and wattles weight, according to the breed, were calculated at 168 days of age. For ER no significant correlation was found, whereas RL showed a significant (P<0.01) positive relationship between testes weight and body weight, and sexual secondary characters. Robusta maculata showed a significant correlation between testes weight and comb (P<0.01) and wattles weight (P<0.10). Our results suggest that under the studied environmental conditions ER showed the highest testes development according to its more precocious achievement of adult body weight, whereas RL was the least precocious purebred.