The aim of the present study was to verify some parameters for evaluating frozen semen, throughout pregnancy rate, in sheep. Two hundred and ninety-seven ewes from the Corriedale breed were inseminated by laparoscopic method. The estrus were synchronized with intravaginal sponge, containing 50 mg of MAP (medroxyprogesterone acetate), for 12 days and eCG (Equine Chorionic Gonadotrophin; 400 IU) was given in a single intramuscular injection at the moment of withdrawing the sponges. The semen from 32 rams was frozen in pellets. Semen of different qualities was used. The quality of the semen was determined by evaluating sperm motility at thawing, sperm motility after 5 hours incubation, the mean of sperm motility during incubation period (0, 1, 2, 3, 4 and 5 hours) and the percentage of normal sperm cells. Each of these parameters was correlated with pregnancy after laparoscopic insemination. The diagnosis of pregnancy was performed by ultrasonography at 40 days after insemination. The percentages of pregnancy were from 60% to 80% only when the sperm samples exhibited sperm motility higher than 40% (68.1), mean of sperm motility and after thawing at least of 20% (64.4 and 72.3) and sperm motility after 5 hours of incubation superior to 10% (61.1 and 78.6). With regard to the percentage of viable cells, the samples with at least 40% of sperm motility resulted in 61.8% and 66.4% of pregnancy while sperm motility less than 40% resulted in only 15.2%. The parameters investigated were efficient to evaluate the capacity of frozen semen to fertilize sheep to use in laparoscopic insemination.
Frozen semen; Intrauterine insemination; Laparoscopy; Sheep
