Effective cryopreservation of western capercaillie (Tetrao urogallus) semen using dimethylsulphoxide

This work examines the use of Me₂SO as a cryoprotective agent (CPA) for capercaillie semen, comparing it with the use of dimethyformamide (DMF). Thirty semen samples were collected from seven males, diluted and divided into two aliquots before adding either Me₂SO (final concentration 8 %) or DMF (6 %). These samples were then frozen in liquid nitrogen vapour. No significant differences were seen between the Me₂SO and DMF treatments with respect to any frozen-thawed sperm motility characteristics, and plasma membrane integrity, although the proportion of viable spermatozoa showing normal morphology was greater (P < 0.05) with the DMF treatment. The proportion of sperm showing a bent neck was greater in samples frozen with Me₂SO than in fresh sperm (P < 0.001), and than in samples frozen with DMF (P < 0.05). Thus, although Me₂SO appears to be a suitable CPA for freezing capercaillie semen, some variables are slightly better when DMF is used.