Avaliação da IATF em novilhas Girolando utilizando-se diferentes protocolos com sêmen sexado: comunicação breve

The aim of this study was to compare results of different protocols of timed artificial insemination (TAI) using sexed semen on reproductive efficiency in Girolando cattle. Sixty two heifers were used, being clinically healthy with a body score condition between 2,5 and 3,5, divided randomly into three groups: control (n = 21), FSH/LH (n = 21) and eCG (n = 20). All animals received the same hormonal treatment to synchronize estrus, consisting in inserting na intravaginal device with 750 mg of progesterone (P4) plus 2 mg of estradiol benzoate (EB) on day 0 (5:00 PM). On day 8 (5:00 PM), the device was removed, and 2 ml of prostaglandin (0,5 mg of cloprostenol) were administered. On day 9 all animals received 1 mg of estradiol benzoate (EB; 5:00 PM), and were inseminated on day 11 at 5:00 AM, 60 h after device removal. On day 8, heifers were randomly assigned into three groups. Control group without FSH/LH and eCG; group FSH/LH - 25 IU FSH and LH administered after device removal, group eCG - 300 IU eCG administered after device removal. Heifers were examined by ultrasonography 35 days after AI for pregnancy diagnosis and 45 days for evaluation of embryonic death. Pregnancy rates for control, FSH/LH, and eCG groups were, respectively, 19, 28 and 35%. Data were analyzed by chi-square, with 5% significance level. No significant difference was seen between-groups. When control and eCG groups were, compared in heifers not cycling, a difference in pregnancy rate was observed. It is concluded that in cycling animals, eCG and FSH/LH does not interfere with pregnancy rates, however in those heifers that were not cycling or had follicles smaller than 8 mm, eCG had a favorable effect thereby increasing substantially the results.