Effect of different types of artificial insemination and semen dose on reproductive efficiency in mares

Abstract

The present study was designed to assess the effect of conventional artificial insemination (CAI) and deep intrauterine artificial insemination (DAI) using different concentrations of spermatozoa on the production of embryos in mares during two breeding season (BS). Seventy-four estrus cycles from 13 crossbred mares (Criollo/English Thoroughbred/Quarter horses) were evaluated, considering the location of semen deposition and doses of fresh semen. The animals were assigned to two treatments: treatment CAI (AI on the uterine body; n = 38) and treatment DAI (AI at the apex of the uterine horn, ipsilateral to an ovary with a preovulatory follicle (POF); n = 36). The animals in estrus were evaluated by ultrasonography to measure the dimensions of the POF. It was observed that POF was larger than 33 mm in diameter than uterine edema and a cervical opening grade of 3, 750 mg of deslorelin acetate (IM) was injected. Twenty-four hours later, AI was performed. The CAI mares received 500 ×10 6 progressively mobile spermatozoa (PMS) and the DAI mares received 250 ×10 6. Embryo collection occurred on days 7 or 8. The embryo recovery rate (ERR) was 68.4 % (26/38) for CAI and 72.2 % (26/36) for DAI. No significant difference was found for the ERR for either of the two AI methods or the sperm doses used. In conclusion, both AI methods can be used successfully in horses and it is possible to reduce the dose of PMS by 50 % when using DAI without decreasing the fertility rate. The production of embryos may be performed several times during the breeding season in the same mare.