Abstract

This work was designed to make further observations on the specific types of sperm abnormalities present in Cypermethrin treated rams and contribute information towards understanding how Cypermethrin affects male’s reproduction. Sixteen sexually-mature, healthy Yankasa rams aged 18 to 30 months and weighing between 21.5 to 46.5 kg were used. The 16 rams were divided equally into two groups (A and B). Group A served as the treatment group, while B served as the control. The rams in Group A were given Cypermethrin (3%) at the dose rate of 3 mg/kg (0.1 ml/kg) body weight, topically as pour-on. The control rams were given distilled water at the same dose rate and route. These treatments were repeated every two weeks for a period of 12 weeks. Semen was collected on weekly basis from each ram during the experimental period by means of a hand held electro-ejaculator (EE). The morphological sperm abnormalities/defects were determined by examining semen smears stained with eosin-nigrosin on a glass slide. Results showed that sperm abnormalities recorded were detached head, mid piece droplet, free tail, coiled tail and bent tail.  There was no significant difference in the percentage of these abnormalities recorded between the two groups (p>0.05) from week 1 to 12. It is concluded that Cypermethrin did not induce any specific sperm abnormalities in rams treated with 3 mg/kg body weight as pour-on. Sperm death in Cypermethrin label dose treated rams may be mediated through oxidative stress. It was recommended that more studies be directed towards stress biomarkers in Cypermethrin treated rams.

Key words: Sperm, abnormalities, cypermethrin, rams, oxidative stress.