Effects of exogenous estradiol-17 beta on luteinizing hormone, progesterone, and estradiol-17 beta concentrations before and after prostaglandin F2 alpha-induced termination of pregnancy and pseudopregnancy in gilts.
This study evaluated the influence of exogenous estradiol-17 beta (E2) administration on LH concentrations and the number of animals returning to estrus after the termination of pregnancy or pseudopregnancy in gilts. Gilts were mated (pregnant; n = 11) on the 1st d of estrus or received 5 mg of estradiol valerate i.m. at d 11 to 15 after the onset of estrus (pseudopregnant; n = 9). Gilts were treated with prostaglandin F2 alpha (PGF2 alpha, 15 and 10 mg) at 12-h intervals on d 44 of pregnancy or pseudopregnancy. The day of abortion or luteolysis (progesterone less than .2 ng/mL) was considered d 0. Six pregnant and four pseudopregnant gilts received s.c. an E2 capsule (24 mg of E2) on d -20 and additional E2 capsules on d -13 and -6. The E2 capsules were removed on the day after PGF2 alpha administration. Blood samples were collected at 12-h intervals from d -21 to -3, at 6-h intervals from d -2 to 21 or the onset of estrus, and at 15-min intervals for 8 h on d -2, 1, 4, 7, 10, 14, and 18. After each 8-h sampling period, gilts were treated i.v. with GnRH at .5 micrograms/kg of BW and blood samples collected at 10-min intervals for 3 h. A greater (P less than .05) proportion of sham-treated gilts than of E2-treated gilts exhibited a preovulatory-like LH surge after abortion/luteolysis. It was evident that E2 supplementation before luteolysis reduced the ability of pregnant and pseudopregnant gilts to return to estrus.
Smith
C A
CA
Department of Food Animal and Equine Medicine, North Carolina State University, Raleigh 27606.
Almond
G W
GW
Esbenshade
K L
KL
D000028:Abortion, Induced / Q000662:veterinary*; D000818:Animals; D015237:Dinoprost; D004958:Estradiol / Q000097:blood / Q000494:pharmacology*; D004971:Estrus / Q000187:drug effects; D005260:Female; D007986:Luteinizing Hormone / Q000097:blood* / Q000378:metabolism; D010053:Ovary / Q000187:drug effects; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D011555:Pseudopregnancy / Q000097:blood / Q000662:veterinary*; D011897:Random Allocation; D013552:Swine / Q000502:physiology*
D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D015237:Dinoprost