Extenders Containing Dimethylformamide Associated or Not with Glycerol are Ineffective for Ovine Sperm Cryopreservation

The study aimed at testing the effectiveness of dimethylformamide, alone or combined with glycerol, as cryoprotectant for freezing ram semen. Ejaculates from nine rams were cryopreserved in Tris‐based extenders, containing 5% of glycerol, association of dimethylformamide with glycerol, in four proportions achieving 5% of cryoprotectors in the media and pure dimethylformamide (2, 3, 4 and 5%) in replacement to glycerol. The samples were diluted to 100 × 106 sptz/ml and stored in 0.25‐ml straws in liquid nitrogen. After thawing (37°C for 30 s), motility was preserved better by the extender containing 5% of glycerol (p