Effect of Dursban 44 on semen output of Holstein bulls.

Dursban 44, an insecticide for lice control, was applied to 185 Holstein bulls 9 to 52 mo of age. These sires were in various stages of progeny testing at an artificial insemination center. Application of this product killed 7 bulls, and the remaining bulls exhibited varying severity of illness with 6 classified as very sick. This study evaluated the effect of this illness on semen production. Semen output on 40,950 ejaculates from 583 Holstein bulls collected from July 1, 1975, through March 31, 1981, was analyzed to establish normal semen production and to estimate the effect of illness caused by Dursban 44 treatment. Ejaculate number, days between collections by previous number of ejaculates, calendar months, years, and ages of bulls affected the semen output characteristics, original volume, sperm concentration, percent motile sperm, total sperm per ejaculate, percent prefreeze discards, percent postthaw sperm motility, and percent postthaw discards. Ejaculate volume, motility, total percent prefreeze discards, and percent postthaw discards were influenced negatively on the 6 very sick bulls. Percent postthaw discards were higher on all bulls treated with Dursban 44 for up to 6 mo post-treatment.