2. Department of Animal Sciences, University of Illinois, Champaign-Urbana, IL.
3. Department of Animal Sciences, Louisiana State University, Baton Rouge, LA.
The increased use of assisted reproductive technologies (ARTs), increase the risks of erroneous prostaglandin F2α (PGF2α) administration. The objective of this study was to determine if pregnancies could be maintained if P4 was administered after PGF2α administration. A total of seven pregnant heifers between 30 - 40 days of gestation and 19 pregnant cows between 30 to 40 (n=12) or 80 to 90 (n=7) days of gestation were used. All females were administered a maintenance dose of P4 or progestin at either 2, 6, 8, 10, 12 or 18 hours post-PGF2α for 7 days. A total of 18 of 25 (72%) pregnancies were maintained for a minimum of 7 days. The success rate for cows and heifers receiving P4 or progestin 2, 6, 10, 12 or 18 hours after PGF2α was 4/6 (75%), 6/6 (100%), 2/3 (67%), 2/4 (50%), 1/2 (50%) and 3/4 (75%), respectively. Maintenance P4 or progestin was continued on selected females (12 of the 18) and they were examined via ultrasonography 2 to 3 times weekly until a follicle ≥10 mm developed on the ovary ipsilateral to the gravid uterine horn, at which time hCG (2,500 IU) was administered. Luteal tissue was successfully induced in 10 of the 12 (83%) and 8 of these calved (80%). These results indicate that it is possible to maintain a bovine pregnancy by administering maintenance dose of P4 from 2 to 18 hours post-PGF2α.
Keywords: Cattle, abortion, induced luteal tissue, pregnancy, progesterone