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Reproductive performance after two different breeding protocols following intravaginal OvuGel® administration in Matrix® treated gilts
The objective was to compare the reproductive performance of gilts using two breeding protocols after OvuGel® (OG) treatment 126 hours following the last feeding of Matrix® and gilts inseminated when found in estrus. Danbred gilts (n=814) were blocked by date of first estrus and body condition score and allocated to one of three treatments: Control (272), OG1 (270), and OG2 (272). All gilts were fed 15 mg Matrix®/gilt/day for 14 days. All gilts were observed daily for behavioral estrus starting on day 4 post-Matrix® and continuing until gilts no longer expressed estrus or until day 9 after last Matrix®. Controls were inseminated the first day in estrus and each day they remained in estrus. OG1 and OG2 gilts were administered OvuGel® 126 hours after the last feeding of Matrix®. OG1 and OG2 gilts received a single insemination 24 hours post-OvuGel®, regardless of estrus status. OG2 gilts that were expressing estrus 24 hours after the first insemination received a second insemination. Control gilts averaged 1.9 inseminations per gilt, OG1 gilts received 1 insemination per gilt, and OG2 gilts had 1.4 inseminations per gilt (P<0.01). There were 11.4% of the Control gilts that did not express estrus by day 9 post-Matrix® compared to 30.0% and 30.2% for the OG1 and OG2 gilts, respectively (P<0.01). There was no difference (P>0.99) in percentage pregnant at 30 days of gestation among Control (80.6%), OG1 (80.9%), and OG2 (81.0%) gilts. Percentage farrowed was also not different (P>0.78) among Control (75.9%), OG1 (78.3%), and OG2 (77.7%) gilts. The OG2 gilts had fewer total pigs born per litter (13.4 vs. 14.4, P<0.01) and fewer born alive per litter (12.6 vs. 13.4, P<0.05) than Control gilts. However, total pigs born per litter was similar (P>0.11) for Control and OG1 gilts (14.4 and 13.9, respectively). Likewise, number born alive per litter was not different (P>0.22) among Control (13.4) and OG1 gilts (13.0). Total pigs born per semen dose was 6.6, 10.8, and 7.3 (P<0.01) for Control, OG1, and OG2 gilts, respectively. These data indicate that administering OvuGel® to gilts 126 hours post-Matrix® and inseminating a single time 24 hours later, regardless of estrus status, results in farrowing rates and litter sizes comparable to gilts receiving multiple inseminations following detection of behavioral estrus. In addition, a second conditional insemination proved unnecessary and illustrated the risk of inseminating animals after ovulation.
Keywords: gilt, reproduction, OvuGel®