EFFECT OF X-RADIATION UPON THE QUALITY AND FERTILITY OF STALLION SEMEN

The exposure that stallion semen might receive during examination usin g an airport x-ray security screening system was found to be between 0 .5 and 1.0 micro Sieverts (mu Sv). Ejaculates from 2 stallions were di luted 1:4 (volume:volume) using a nonfat dried milk-glucose extender. A total of 6 ejaculates from each stallion was collected, and each eja culate was divided into 3 aliquots and these were then exposed to x-ra diation at a dose of 0, 1.0, or 10.0 mu Sv. Semen quality was examined immediately post exposure, and the aliquots were then placed into a w ater bath at 37 degrees C, after which sample longevity was evaluated. In a second trial, 3 groups of 8 pony mares were inseminated with sem en that had been exposed to x-radiation at doses of 0, 1.0, or 10.0 mu Sv. An entire ejaculate was irradiated and inseminated into each mare on one occasion during estrus, based upon ultrasonographic evaluation of the reproductive tract. After exposure to x-radiation there were n o differences among the 3 treatment groups for spermatozoal motility, morphology, or longevity. The 14-d pregnancy rates for the 3 treatment groups were 0 mu Sv (7 mares), 1.0 mu Sv (8 mares), and 10.0 mu Sv (7 mares). One mare (0 mu Sv) aborted at 65 d of pregnancy; 21 mares had a pregnancy of normal length, with each delivering a foal at term, al though 1 foal died at parturition (2.0 mu Sv). These findings indicate that the exposure of stallion spermatozoa to x-radiation up to doses of 10 mu Sv does not have deleterious effects upon spermatozoal motili ty, morphology, longevity or fertility. The exposure received during e xamination using an x-ray security screening system is likely to be lo wer than this dose.