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 F 2α 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.Keywords: cattle, artificial insemination, spermatozoan motility, semen extender, prostaglandin F 2α
ImplicationsPregnancy rates of well below 50% are common in most dairy operations. There is published evidence that addition of prostaglandin F 2α (PGF 2α ) to semen may improve conception rates, presumably by enhancing uterine contractility, and thus sperm transport to the site of fertilization. This could be particularly beneficial when inseminating with small sperm numbers, for example, sexed semen. The present study establishes preconditions (suitable semen extender, PGF 2α concentration tolerated by sperm cells and invention of a two-column straw artificial insemination technique) for implementation of a large-scale field investigation.
IntroductionThe present study addresses the establishment of preconditions for a large-scale field trial aimed at verifying results reported by Gabriel et al. (2011), suggesting that intrauterine administration of prostaglandin F 2α (PGF 2α ) at the time of insemination improves the pregnancy rate in dairy cows. In that trial, i.m. injection of either Dinoprost (Dinolytic ® , Dinoprost-Trometamol; Zoetis, Berlin, Germany) or the synthetic PGF 2α analog cloprostenol was ineffective, and so was intrauterine infusion of cloprostenol. Intrauterine infusion of Dinoprost, however, brought about an increase in the proportion of cows falling pregnant. At slightly >220 cows/ treatment, the effect was not statistically significant (P = 0.12). Before initiating a new study involving substantially more animals per treatment, the practicability of the treatment was improved by incorporating Dinoprost into the insemination straw instead of having to administer it separately as practiced by Gabriel et al. (2011). The first intention of the present study was to compare various semen extenders on the basis of post-thaw motility. As a second step the concentration of Dinolytic ® that is tolerated by sperm cells was determined. Previous in vitro exp...
