PHYSIOLOGICAL AND HISTOLOGICAL RESPONSES OF GIMMIZAH COCKERELS TO GNRH INJECTION

Abstract

This study was conducted to study the neuroendocrine control of spermatogenesis of Gimmizah Cocks. A total of 300 Gimmizah cockerels aged 5 weeks were selected according to their configuration. Birds were individually weighted and then randomly distributed into 4 experimental groups with 75 males of each. The first group of cockerels (T1) was injected with saline solution for the whole period (6 – 14 wk.) and was considered as a control group. The other 3 groups were injected with a synthetic (Receptal) gonadotropic releasing hormone (GnRH) during the periods from 6 -10 (T2), 8-12 (T3) and 10-14 (T4) weeks of age for the second, third, and fourth groups, respectively.The cockerels of the treated groups were divided into two subgroups the first one (R1) injected with 0.1 ml Receptal / kg of body weight, while the second (R2) injected with 0.2 ml Receptal / kg of body weight. Data obtained illustrated that at 12 weeks of age, the plasma level of LH, FSH and testosterone were insignificant. LH and FSH values of T2 group at 14 weeks of age were lower than that recorded for the other treated or control groups. At 16 weeks of age, the plasma concentrations of all hormones were comparable to those obtained at 14 weeks of age. Semen quality traits were significantly improved by injecting GnRH regardless the injected dose. These results suggested that the precocious puberty in Gimmizah males could be achieved by GnRH injection starting from 8 or 10 weeks of age as a result of increasing the spermatogenic activity.