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Single fixed-time insemination following OvuGelŪ administration in postpartum sows
The objective was to determine the effect of a single, fixed-time insemination 24 h after OvuGel® (OG) administration on subsequent farrowing rate and litter size. Weaned PIC sows (n=359) were blocked by parity and body condition score and allocated to one of two treatments: Control (179) and OG (180). All sows were observed daily for behavioral estrus starting on d 4 post-weaning and continuing until sows no longer expressed estrus or until d 7 after weaning. Controls were inseminated the first day in estrus and 24 h later if still in estrus. OG sows were treated with OvuGel® on d 4 after weaning and were inseminated once approximately 24 h post-OvuGel® treatment, regardless of estrus status. Control sows averaged 2.0 inseminations per sow while all OG sows had 1 insemination per sow (P<0.01). Of the 179 Control sows, 163 (91.1%) expressed estrus and were bred by d 7 post-weaning. All 180 OG sows were mated even though only 159 (88.3%) expressed estrus. There was no difference (P>0.89) in percentage pregnant ([number of pregnant sows/weaned sows to breed] x 100) at 30 d of gestation (Control 88.3, OG 87.8). Percentage farrowed ([number of sows farrowed/weaned sows to breed] x 100) was also not different between Control and OG sows (P>0.67; Control 84.5, OG 82.8). Gestation length was shorter (P<0.01) for OG sows (115.7 d) compared to Control sows (116.3 d). Total pigs born per litter averaged 14.2 and 14.5 for Control and OG sows, respectively (P<0.48). Of the 21 OG sows that were not expressing estrus when inseminated, eight farrowed (38.1%) and had 13.3 total pigs per litter. Total pigs born per semen dose was 6.7 vs. 12.0 (P<0.01) for Control and OG sows, respectively. These data indicate that treating sows with OvuGel® followed by one insemination approximately 24 h later results in farrowing rates and litter sizes comparable to sows receiving multiple inseminations during behavioral estrus. The possibilities of improving utilization of weaned sows, increasing the effectiveness of timed inseminations and equal fertility from fewer semen doses offer increased returns from superior boars, programmed gilt insertions, better utilization of breeding technicians and older pigs at weaning from all in: all out flows.
Keywords: sow, reproduction, OvuGel®