Cottonseed feeding delivers sufficient quantities of gossypol as a male deer contraceptive

To define the quantitative and qualitative effects of gossypol (GP) on deer (Cervus elaphus) semen, the animals were fed cottonseed (CS). Adult stags each received 350 g of CS for 109 days. Animals received 15 mg of gossypol per kilogram body weight per day. Quantitative and qualitative parameters of experimental ejaculates (n = 182) were compared to ejaculates (n = 571) of control animals (n = 5) collected during three previous natural reproductive seasons. Ejaculate fractions were evaluated by classical methods used in domestic animals. In this paper, we show that mature male deer fed CS exhibited morphological changes and decreased motility of spermatozoa and abnormalities in spermatogenesis. Radioimmunoassay measured concentrations of various steroid hormones (T-testosterone, A₄-androstenedione, and E₂-estradiol 17β) in separated ejaculate fractions of the CS group were compared to a control group of stags. Generally, mean steroid concentrations in CS-treated deer decreased during the entire sampling period in examined ejaculate fractions. These changes resulted in decreased semen quality with no detectable side effects in the animals. It seems that gossypol fed to the deer in the form of CS serves as an efficient male contraceptive.