Effect of Thyroxine on Sexual Behaviour and Semen Ouality in Bucks

Twelve mature (4-5 years) Egyptian baladi bucks ofgood general health condition were used. The bucks werefed on a known concentrate mixture and green fodder.Three experiments were conducted to investigate theeffect of thyroidal therapy on sex drive and semencharacteristics. L-thyroxine was administered per os ina dose of 0.1, 0.2 and 0.3 mg daily for a period of 4weeks in each experiment. series of 2 successive ejacul-ates were collected weekly for the whole experimentalperiod ($ weeks; 2 pre-, 4 during- and 2 post-treatment).Each collection was examined for sex drive (reaction time),and the ejaculated semen was analysed for appearance,volume, sperm motility, hydrogen ion concentration, alivesperm percentage, sperm cell abnormalities, density, totalsperm output, initial fructos e concentration and themethylene blue reduction time.Effect of sequence of ejaculation on goat semenrevealed that the volume, pH, alive sperm percentage, spermconcentration per ejaculate and initial fructose concentrat-ion were non significantly different between the first andsecond ejaculates. Sex drive declines significantly in the second ejaculates.