Comparison of various semen extenders and addition of prostaglandin F-2 alpha on pregnancy rate in cows

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 (R)), the third (AndroMed (R)) soybean lecithin based. With regard to post-thaw motility, the phytoextender AndroMed (R) 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 F-2 alpha preparation Dinolytic (R) before freezing compromises post-thaw motility; therefore, in Trial 2, Dinolytic (R) was added after thawing. Frozen-thawed spermatozoa tolerated addition of Dinolytic (R) at a concentration of 30% (v/v). In Trial 3, cows were inseminated using straws in which diluted semen and Dinolytic (R) 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 (R) 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.