Luteal Function in Gilts after Prostaglandin F2α

Abstract

Twenty 9-month-old crossbred gilts were randomly allotted to one of four treatment groups to examine the effects of prostaglandin F2α (PGF2α) on estrous cycle length, plasma progesterone, estradiol and LH. Two groups were injected four times intramuscularly at 12-hr intervals starting on day 4 of the estrous cycle with either a total of 80 mg PGF2α or saline. The other two groups were treated similarly except treatments were started on day 12 of the estrous cycle. Estrous cycle length was not altered by PGF2α treatment starting on day 4; but when treatment was initiated on day 12, gilts had shorter estrous cycles than controls (17.2 ± .2 vs 18.6 ± .7 days, respectively, P<.10). The lengths of the estrous cycles after PGF2α given on days 12 and 13 were also shorter than the estrous cycles prior to treatment in the same gilts (P<.01). Plasma progesterone was not altered by treatment with PGF2α on days 4 and 5, but progesterone was reduced (P<.025) in gilts treated with PGF2α on days 12 and 13. Plasma estradiol was significantly elevated (P<.025) in gilts treated on days 12 and 13 compared to control gilts, but plasma LH was not significantly altered by either PGF2α treatment. It was concluded that PGF2α given on days 12 and 13 of the estrous cycle can hasten luteal regression in gilts.