Comparison between two fixed-time artificial insemination protocols in Brahman cows

Objective. To compare two fixed-time artificial insemination protocols (FTAI) according to the pregnancy percentage in Brahman cattle. Materials and methods. 60 cows between days 90 and 360 postpartum were selected and randomly divided into two groups. For Treatment 1 (T1; n=30), an intravaginal device (IVD) containing 0.5 g of progesterone and 2.0 mg of estradiol benzoate were inserted on Day 0. At the time of IVD withdrawal (Day 8), 150 mg of PGF2α, im and 300 UI of eCG, im and 0.5 mg of estradiol cypionate, im were administered. FTAI was performed on Day 10, 48 – 50 h after IVD withdrawal. For Treatment 2 (T2; n= 30) an IVD was inserted on Day 0 and 0.01 mg GnRH, im were administered. At the time of the IVD withdrawal (Day 5), two doses of 0.150 mg of PGF2α were administered at midnight and noon. FTAI was performed on Day 8, 72h after IVD withdrawal, and 0.01 mg of GnRH, im was administered. FTAI was performed using semen of proven fertility. Results. Pregnancy diagnosis by rectal palpation occurred 45 days after the FTAI. T2 and T1 presented pregnancy percentages of 46.7% (14/30) and 33.3% (10/30), respectively. Conclusions. Treatment 2 is preferred in terms of results and public health.