Changes in ovarian structures and hormonal profiles in estradiol dipropionate (EDP)-induced pseudopregnant sows following PGF2α-analogue (PGF2α-A) administration and practicality of the estrus synchronization protocol using EDP and PGF2α-A on estrus expression and reproductive performance in commercial conditions were investigated. Pseudopregnancy was defined as absence of estrus maintained for at least 20 days after EDP treatment in this study. When 4 pseudopregnant sows induced by 20 mg EDP were treated with PGF2α-A as 0.175 mg cloprostenol twice at a 24-hr interval between 20 and 28 days after EDP treatment, plasma progesterone concentrations rapidly decreased after treatment. The luteinizing hormone surge and ovulation were detected in all sows. The number of ovulated follicles was 17.3 ± 1.1 (SEM). On commercial farms, 94.2% of 52 gilts and 95.2% of 21 sows received EDP became pseudopregnant. When these pseudopregnant females (48 gilts and 20 sows) were treated with PGF2α-A as described above, estrus was detected in all females at 6.1 ± 0.3 days for gilts and 5.5 ± 0.2 days for sows after the first PGF2α-A treatment. There were no significant differences in farrowing rate (85.0 - 100%), average total litter size (10.0 - 11.4), average born alive litter size (9.4 - 10.3) and average piglet birth weight (1.56 - 1.71 kg) between PGF2α-A treated pseudopregnant female pigs that were inseminated during synchronized estrus and females inseminated during spontaneous estrus. This study indicates that estrus synchronization programs using EDP and PGF2α-A are available as practical and convenient procedures for commercial pig farms.
2013 by the Japanese Society of Veterinary Science