The effects of adding fulvic acids (FAs) to semen extenders on the quality parameters of frozen–thawed goat buck spermatozoa remain undetermined. Buck semen samples collected from six mature goat bucks once a week were diluted with Tris–egg yolk-based extenders. The diluted semen samples were supplemented with FAs (0.2, 0.4 and 0.6%, w/w), cryopreserved, and evaluated for sperm-quality parameters. Addition of FAs to the extender increased progressive motility, acrosome integrity, membrane integrity, and superoxide dismutase and catalase activities and decreased percentage abnormality and sperm malondialdehyde level compared with the control group. However, excessive FA addition (>0.4%, w/w) to semen extenders did not improve the efficiency. The results indicated that FAs could be a promising cryoprotectant for goat buck sperm.

This investigation comprises three trials. Trial 1 consists of an in vitro comparison of three semen extenders: two egg yolk based (customized Tris-egg yolk-glycerol and Triladyl®), the third (AndroMed®) soybean lecithin based. With regard to post-thaw motility, the phytoextender AndroMed® proved to be superior (59±3% v. 53±2% and 53±2%, P<0.05). It had earlier been shown that addition of the commercial prostaglandin F2α preparation Dinolytic® before freezing compromises post-thaw motility; therefore, in Trial 2, Dinolytic® was added after thawing. Frozen-thawed spermatozoa tolerated addition of Dinolytic® at a concentration of 30% (v/v). In Trial 3, cows were inseminated using straws in which diluted semen and Dinolytic® were frozen in the same straw, separated by an air bubble, so intermingling could only take place in the course of insemination. Pregnancy rates at Dinolytic® dosages of 0%, 30% or 60% amounted to 44%, 41% and 56%, respectively (P>0.05), a result that encourages a large-scale field study, which is envisioned.