The present paper describes the effect of cell surface sialic acid on the orientation of motile and killed sperm of cattle in a 5400-G magnetic field. Cattle sperm collected from six bulls was placed in the medium. The semen suspensions were divided into motile, freeze-killed, and naturally dead sperm samples. An aliquot of the sperm samples were incubated with an added 1.0 mg / ml neuraminidaseat 30°C for 1 hour. Neuraminidase-treated and nontreated samples were exposed continuously for 24 hours to a magnetic field of 5400 G at 38°C. Neuraminidase treatment enhanced the orientation of the sperm. Naturally dead sperm treated with neuraminidase and exposed to the mgnetic field had the highest percentage of orientation. These findings suggest that a negatively charged cell surface inhibits sperm from orientating. However, freezekilled sperm had a lower percentage of orientation than naturally dead and motile sperm.
