Syncronisation of oestrus cycle in cattle with prostaglandin F2alfa. I . Effects according to the site of injection on the genitals.

Abstract

Fifty-three randomly cycling Holstein-Zebu or Jersey-Zebu nuliparous cows were allotted in treatments with 6 mg of PGF2alfa-THAM salt, as follows: A — into the uterine horn ipsilateral to the active corpus luteum of 16 animals; B — into the body of uterus of 16 animals; C — into the middle portion of the cervix of 15 animals and D — 6 control animals, showing signs of oestrus, and that were inseminated at about 12 and 20 hr after onset of oestrus. A second injection of 6 mg of PGF2alfa was made, 10 days later, into the body of uterus of 10 animals, among those 22 that failed to show oestrus. So, there were made 26 injections into the body of uterus. In 35 cows standing oestrus occurred at 2.9 ± 0.1 days, with a synchronisation index of 81.2%, 69.2% and 26.6% for groups A, B and C. All animals showing standing oestrus were inseminated with frozen semen 12 and 20 hr after the first signs of oestrus. Pregnancy rates were 1/6.1%, 22.2% and 0.0% for treated groups and 66.6% for the control. Examination of the reproductive tracts of 10 animals slaughtered lfi days after the first treatment revealed, no clinical, signs of infection.