Testicular growth in three italian chicken genotypes reared under free range conditions

The aim of this trial was to study testes growth in three Italian chicken breeds, Ermellinata di Rovigo (ER), Robusta lionata (RL) and Robusta maculata (RM). These breeds originates from Veneto region, in Northern Italy. The birds were reared under free-range conditions from 46 until 168 d of age, from June to November in Northern Italy. Natural photoperiod was decreasing (from 15 to 10.5 h) as well as environmental temperature (from 23±5 to 16±4°C). At 138 and 168 d of age 12 birds per breed were slaughtered and their testes were collected, weighed and then fixed in 10% formalin, and embedded in paraffine wax. Serial sections (10 μm) were stained for morphological observations. Four stages of testis maturation were considered: Class 0: seminiferous tubules with a simple single layer of spermatogonia and Sertoli cells, (prepubere testis); Class 1: seminiferous tubules with 2 layers of cells; appearance of primary spermatocytes moving away from the basement membrane; Class 2: seminiferous tubules with 3-4 layers of cells; Class 3: seminiferous tubules with 5-8 layers, presence of mature sperm cells in the lumen. Data were analysed by GLM using the SAS package. ER showed a lower (P<0.01) body weight in comparison to RL and RM males. At 168 d, ER reached 84% adult body weight, whereas RL and RM reached 79%. ER showed higher (P<0.01) testes weight in comparison to the other two breeds; ER testes highlighted mature sperm cells. From 138 to 168 d of age a tendential increase in testes maturity was observed only in RM breed.