THE USE OF A DICHROMATIC STAIN METHOD (SPERMAC(R)) FOR DETERMINING CHANGES IN THE ACROSOMAL INTEGRITY OF BOAR SEMEN DURING CRYOPRESERVATION

The value of the dichromatic Spermac(R) stain for evaluation of the ac rosomal integrity of boar semen during cryopreservation was tested und er field conditions with bright-field microscopy in comparison with mo tility. Ejaculates from 16 fertile, randomly chosen Norwegian Landrace boars were frozen. At four different steps (I-IV) of the preservation process (30, 15, 5 degrees C, and after freezing/thawing) samples wer e taken and both motility and acrosomal integrity were assessed. The s taining quality of smears in steps I and II was high, but marginal for smears in steps III and IV, though allowing evaluation. The correlati on between motility and acrosomal integrity was low in all four steps (r(I) = 0.15; r(II) = 0.11; r(III) = 0.33; r(IV) = 0.19). From step I to IV, motility and acrosomal integrity were reduced from 72 to 23% an d from 97 to 17%, respectively. For both parameters, the results were not significantly different between steps I and II, but the difference was highly significant between steps II and III and steps III and IV. The most dramatic reduction occurred during freezing/thawing, with a difference of 41% for motility and 68% for acrosome integrity. It is c oncluded that the Spermac(R) stain method could be a valuable tool for the assessment of the acrosomal status of boar semen during cryoprese rvation.