Postweaning Plasma Concentrations Of Luteinizing Hormone And Estrogens In Sows: Effect Of Treatment With Pregnant MareS Serum Gonadotropin Or Estradiol-17 Plus Progesterone

Dyck, G.W.; Palmer, W.M.; Simaraks, S.

Canadian Journal of Animal Science 59(1): 159-166


ISSN/ISBN: 0008-3984
DOI: 10.4141/cjas79-019
Accession: 068493105

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The plasma concentrations of luteinizing hormone (LH) and estrogens (E) were determined for 12 sows, from a herd with a history of postweaning anestrus, from the day of weaning to 32 days after weaning (trial I). A linear increase in plasma LH and E was observed in six sows which remained in anestrus (LH, 0.32–0.47 ng/ml; E, 16.1–24.7 pg/ml). These concentrations were similar to those observed in cycling sows during diestrus. In the remaining sows concurrent peaks of LH and E were observed during proestrus and estrus. In a second trial, two groups each of five sows were treated with a single injection of pregnant mare's serum gonadotropin (PMSG, 1500 IU) or steroids (estradiol-17β, 1 mg plus progesterone, 2 mg) on the day after weaning. The plasma concentrations of LH and E for 10–12 days after weaning were compared with those of five untreated control sows. In the PMSG-treated group, concurrent peaks of LH (4.7 ± 0.5 ng/ml) and E (121 ± 41 pg/ml) were observed at estrus. The control group produced a lower LH peak at estrus (1.5 ± 0.4 ng/ml) which was not accompanied by a rise in plasma E. No consistent secretory pattern for plasma LH and E was observed in the steroid treatment group.