Efeito da idade de éguas doadoras em programas de transferência de embriões

Abstract

The study aimed to evaluate the influence of the age of equine donors on the efficiency of the Embryo Transfer Program. 57 donors of the Quarter Horse breed were used, aged between five and 25 years, divided into three treatments (T), being: females aged five to 15 years; T2 (n=24): between 16 and 19 and T3 (n=6): between 20 and 25 years. Fresh semen diluted from 2 Quarter Horses stallions was used. The donors were inseminated through a follicle of 30-35 mm in diameter and the presence of uterine edema, on day 8 after ovulation, uterine lavage was performed in order to recover one or more embryos, when recovered, they were evaluated, manipulated and innovated in a recipient in order to obtain a pregnancy. A total of 208 uterine lavages were performed, distributed in the three treatments, T1 (68); T2 (114) e T3 (26). Embryonic recovery rate, number of embryos per cycle and pregnancy rate at 60 days were evaluated. The data did not present a normal distribution, the Kruskal Wallis test was used, at 5% significance level. The rate of embryonic recovery was higher for females aged 5-15 years, with 92.75% recovery and there was no difference between 16-19 year old mares, with 58.77% and over 20 years old, with 65%. The number of embryos recovered per cycle was higher in mares aged 5-15 years (1.14 embryos / cycle), when compared to mares aged 16-19 years (1.02) and over 20 years (1.0), no difference between these last two groups. The gestation rate achieved with the embryos transferred was higher for younger mares (62.32%), compared to mares aged 16-19 years (34.21%) and above 20 years (23.08%). The advancement of age has a negative effect on the reproductive efficiency of mares in ET programs, with a decline in the rate of embryonic recovery, a reduction in the number of embryos per cycle and a gestation rate from 16 years of age.