Abstract

CAZALES PENINO, Nicolás; ESTRADE, María José  and  COSTA MATTOS, Rodrigo. Artificial insemination with frozen equine semen: inflammatory reaction, sperm transport and insemination technique. Veterinaria (Montev.) [online]. 2020, vol.56, n.214, e401.  Epub Dec 01, 2020. ISSN 0376-4362.  https://doi.org/10.29155/vet.56.214.2.

The aim of the following review is to discuss the effect on fertility of some factors classically recognized as relevant to the success of artificial insemination (AI) with frozen equine semen: total sperm numbers per AI (dose), number of inseminations per cycle (AI frequency), optimal timing of AI relative to ovulation, AI site and AI techniques. The frozen semen AI is widely used in the equine industry. The minimum recommended dose of spermatozoa has been established in 250 x 106 progressive motile sperm for uterine body insemination. However, the minimum dose required for maintaining the highest fertility for each stallion may differ greatly and therefore is determined by individual variation of intrinsic stallion fertility as well as with the insemination site. Deep intra-uterine insemination is commonly accepted as a routine procedure for AI with low doses. The number of AIs per cycles does not seem to be a factor affecting the final outcome of pregnancy as long as the last AI is performed within 12 h before and 12 h after the ovulation. Contrary to the extended practitioners belief, the mare’s oocyte could remain viable and fully capable of fertilization for 12-15 h, and the embryo loss rate after post-ovulatory insemination does not begin to increase until 12 h post-ovulation. Therefore, in a postovulatory insemination regime and using an ovulation inducing agent, examination of mares at intervals of any less than 12 h does not improve pregnancy or embryo loss rates. In conclusion, the number and cost of available semen doses, status of the mare to be inseminated and fertility of the frozen semen will determine the AI technique.

Keywords : Low dose insemination, Deep-horn insemination, Frozen semen, PMNs, Stratum compactum; Stratum spongiosum.

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