Short term administration of cyproterone acetate for contraception: Effects on testosterone secretion and semen characteristics in rams (Ovis aries) and bucks (Capra hircus)

Abstract

Aim of study: To examine the influence of administering cyproterone acetate (CPA), at the beginning of the mating season, on the testosterone concentration and morphometric and functional characteristics of ram and buck semen. Area of study: Madrid, Spain Material and methods: Five rams and five bucks were intramuscularly administered 200 mg of CPA in 2 mL of olive oil twice per week - from July 1st to 31st in the rams, and from August 1st to 31st in the bucks. Five control animals of each species were administered 2 mL of olive oil. Blood samples and ejaculates analysed from the start of treatment until eight weeks after the last day of treatment. Main results: GLM-ANOVA showed the interaction species × CPA treatment to have effect (p<0.05) on sperm motility, progressive motility and acrosome integrity; and greater effect (p<0.01) on curvilinear velocity (VCL), straight-line velocity (VSL), viability, and morphological abnormalities. In both the rams and bucks, plasma testosterone levels fell from the first week from the start of CPA administration until three weeks after the end of treatment. In rams, the total sperm count, sperm motility, progressive motility, viability, morphological abnormalities, VCL and VSL were all negatively affected by the treatment (p<0.001); acrosome integrity was also affected (p<0.05). In bucks, sperm motility, progressive motility, VCL, VSL and morphological abnormalities were negatively affected (p<0.05). Research highlights: Treatment with CPA affected testosterone secretion, semen characteristics and sperm morphometry in both the rams and bucks, and thus it might be used as short term contraceptive protocol in small ruminants.

Keywords

• livestock
• male reproduction
• ruminants
• sperm
• testicular activity