Effects Of Different Applications Of Pyrethrins And Cyfluthrin, A Synthetic Pyrethroid, On Bull Reproductive Parameters

Abstract

The use of pyrethroid insecticides has been reported to affect semen quality and steroidogenesis in many mammals. Recent experiments with bulls demonstrated no effects on semen quality when the pyrethroid insecticide, cyfluthrin, was applied at labeled dosages. The current study determined effects of cyfluthrin and pyrethrin spray products, used in combination with cyfluthrin pour-on and fly tags, on bull sperm motility and serum testosterone concentrations. Angus x Simmental bulls were assigned randomly to one of two treatment groups: 1) pour-on plus fly tags (CONT; n = 12), or 2) pour-on, fly tags, premise spray plus fog spray (EXP; n = 11). Overall and progressive sperm motility and serum testosterone concentrations were measured weekly for nine weeks. There were treatment by week interactions (P < 0.01) for overall motility, progressive motility, and testosterone concentrations. At week two, overall motility was greater (P = 0.05) for CONT than EXP; however, there were no differences (P ≥ 0.12) at other times. Progressive sperm motility in EXP tended to be reduced (P = 0.07) at week two and increased (P = 0.08) at week seven, but did not differ (P ≥ 0.15) in other weeks. Serum testosterone concentrations were reduced (P = 0.05) at week one in EXP; however, concentrations did not differ again until week nine when EXP bulls had a two-fold decrease (P < 0.01) in serum testosterone concentrations when compared to CONT bulls. This steep decline suggests a delayed effect of the insecticide applications on blood testosterone concentrations.