Seven-day Regumate treatment effective for cycling gilts

Previous studies at the University of Alberta have shown that implementation of an efficient gilt development unit (GDU) management program and the use of Regumate in gilts that have shown estrus is an effective tool in GDU management. The program can be refined further by reducing the period of Rugumate treatment although, to do this, it is essential that the first day of standing estrus is recorded.  Regumate is then administered from day 9-13 onwards, when the natural progesterone level is high. The U of A researchers have compared a 7-day treatment with a 14-day treatment in gilts that either cycled naturally or where estrus was induced using PG600.

Breedings were targeted to occur Tuesday to Friday to avoid weekend breedings, to coincide with semen delivery and optimize quality. Therefore, Regu-Mate treatment was started on a Friday. Gilts detected in heat Saturday – Wednesday of the previous week were allocated to the 7-day protocol (RM7) (corresponding to day 9 -13 of the estrus cycle). Gilts detected in heat on Thursday – Friday from two weeks previous, or cyclic gilts with unknown heat dates, were allocated to the 14-day protocol (RM14).

The percentage of gilts bred within 10 days of Regumate withdrawal was higher (87.4%) in RM7 gilts than RM14 (84.8%).  However, there was no difference in numbers total born or born alive. Gilts that had been treated with PG600 took a longer time to show estrus after Regumate withdrawal (6.6 vs 6.3 days) and fewer of these gilts were bred by 10 days (81.3 vs 91.9 %).  Also, numbers born alive (10.9 vs 11.6 pigs) were lower, although total number born was not statistically different.

WHJ comment:  This work suggests that reducing the number of treatment days when using Regumate to synchronize gilts is effective. It also shows that gilts that did not cycle quickly after boar exposure and were given PG600 to induce estrus had lower fertility.  Regumate and PG600 are both valuable tools in GDU management, however good boar stimulation to induce estrus is the key to achieving a rapid onset of estrus. The use of either a 7-day or a 14-day treatment period with Regumate, depending on when estrus occurs, provides a means of synchronizing gilts that have shown estrus at different times.

Reference: J. Patterson, N. Williams, G. Spronk and G. Foxcroft (2008)  Efficacy of a 7 vs 14 day Regu-Mate protocol in cyclic gilts.  Advances in Pork Production: Volume 19, Abstract #25