Effect of the Timing of Ovugel Administration on Reproductive Performance in Gilts Synchronized for Estrus by Leah Gesing Dissertation

The effect of time of OvuGel administration on timing of estrus and ovulation and fertility results was evaluated in a study involving 448 gilts that had been synchronized for estrus by administering Matrix for 14 d. A RCBD with the following treatments was used: 1) Control (no OvuGel administration), 2) OvuGel administration on d 5 (118 h) after the end of Matrix administration (OV5), and 3) OvuGel administration on d 6 (142 h) after the end of Matrix administration (OV6). Control gilts were inseminated once per each morning of behavioral estrus; gilts administered OvuGel received 1 insemination 24 h after OvuGel administration. Gilts were randomly allotted to treatment within genetic line on the basis of similar live weight and stage of estrous cycle. Gilts were checked for estrus and ultrasonically scanned (transrectally; subsample of 250) at 12 h intervals from d 4 to 10 after Matrix administration. Gilts on the OV5 and OV6 treatments exhibited estrus earlier (P ≤ 0.05) than Control gilts (140.0, 140.9, and 151.3 h after the end of Matrix administration, respectively; SEM 2.51). Ovulation occurred earlier (P ≤ 0.05) for OV5 (164.8 h) than OV6 gilts (174.3 h) and earlier (P ≤ 0.05) for OV6 than Control gilts (189.7 h; SEM 2.17). A greater (P ≤ 0.05) percentage of Control gilts (100.0%) exhibited estrus at insemination than OV5 and OV6 gilts and more (P ≤ 0.05) OV6 gilts (64.6%) exhibited estrus at insemination compared to OV5 gilts (40.4%). Gilts on the OV6 treatment had a lower (P ≤ 0.05) interval from insemination to ovulation than OV5 gilts (8.2 vs. 22.8 h, respectively), and a greater (P ≤ 0.05) percentage of OV6 gilts ovulated within 48 h after OvuGel administration than OV5 gilts (92.5 vs. 70.9%, respectively). Pregnancy rates (percentage of total gilts allotted to the study that were pregnant at 35 d) and farrowing rates