Objective assessment of the cryoprotective effects of dimethylformamide for freezing goat semen

The aim of this work was to assess the cryoprotective effects of dimethylformamide (DMF) for freezing goat semen, using an objective analysis by computer-assisted sperm analysis (CASA). Twenty-one ejaculates (seven per animal) were collected from three stud bucks with the aid of an artificial vagina and immediately evaluated for gross and microscopic characteristics. The semen was diluted in two steps with a Tris-egg yolk extender containing 6% glycerol or 6% DMF, frozen in 0.50-mL straws, and stored in liquid nitrogen. Samples were accessed for sperm morphology, sperm membrane structural and functional integrity, and by CASA, immediately after thawing. There were differences (P < 0.05) between glycerol and DMF with regard to subjective progressive motility (23.9 ± 2.2% vs. 16.6 ± 2.0%), objective progressive motility (3.5 ± 0.4% vs. 1.8 ± 0.3%), linearity (53.9 ± 1.6% vs. 48.1 ± 1.4%) and amplitude of lateral head (2.3 ± 0.1 vs. 2.9 ± 0.1 mm), which confirmed the efficiency of glycerol. In conclusion, dimethylformamide could be used as an alternative cryoprotectant for goat semen freezing. However it was showed that no benefits were derived by using dimethylformamide to replace glycerol at an equal 6% concentration.