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    GnRH Response Test and Libido Scores in Normal and Low-Quality Sperm Producing Rams
    (BLACKWELL WISSENSCHAFTS-VERLAG GMBH, 1993) Aksoy, Melih; Tekeli, Tevfik; Çoyan, K.; Güven, B.; Özar, S.; Alan, M.; Ayar, Ali
    Testicular tissues are responsible for the androgen synthesis as well as the spermatogenesis. Production rate of androgens is affected by many factors. In addition to the hypothalamo- pituitary control, possibly a local substance, which is released by damaged seminiferous tubules, also plays an important role in androgen production of the Leydig cells (Aoki & Fawcett, 1978). Testosterone synthesis can be stimulated by the injection of exogenous gonadotropins and releasing hormones (Hocherau et al., 1990; Post et al., 1987 a,b). Lunstra & Schanbacher (1988) showed that cryptorchid rams had lower basal testosterone levels and a lesser ability to secrete testosterone in response to exogenous LH. Byers & Glover (1984) investigated the effect of scrotal insulation on hormone levels and pointed out that the mean and basal testosterone levels were significantly reduced after 14 days following scrotal insulation. Veeramachaneni et al. (1986) suggested that azoospermic bulls have lower baseline testosterone levels and testosterone response rates to GnRH injections than nor- mozoospermic bulls. GnRH induced testosterone levels in stallions are used as a diagnostic tool to differentiate cryptorchid and castrated animals (Nachrainer, 1986). Post et al. (1987b) reported that GnRH induced testosterone levels might give a valuable information on the selection of the bulls which are adequate to reproductive potential. The present study was designed to evaluate the GnRH response test results of low quality sperm producing and normozoospermic rams comparatively. Libido tests were also performed to assess the libido level of rams with normal or low sperm output.