title: Profiles of ovarian steroids, luteinizing hormone and estrous signs from luteolysis to ovulation in lactating and non-lactating dairy cows.
abstract: The aims of the present study were to investigate the profiles of ovarian steroids and luteinizing hormone (LH) and the appearance of estrous signs in relation to luteolysis and ovulation in lactating and non-lactating cows and to examine the influence of lactation on those observations. Five lactating (daily milk yield of 28.4 ± 3.2 kg; mean ± SD) and five non-lactating cycling Holstein cows were examined. Their ovaries were monitored by ultrasonography daily during one estrous cycle. Blood samples were collected daily and then at 3-h intervals after luteolysis until ovulation. Estrous signs in terms of behavior, the vulva and the vagina were checked at 8-h intervals after luteolysis until ovulation. Profiles of progesterone, estradiol-17β and LH did not differ between the groups. There were no differences in the interval from luteolysis to ovulation (4.6 ± 0.5 and 4.2 ± 0.8 days) and the interval from the estradiol-17β peak to ovulation (34.2 ± 4.5 and 30.6 ± 3.9 h) between lactating and non-lactating cows. The interval from the peak of the LH surge to ovulation was 27 h in all cows examined. Appearance of estrous signs did not differ between the groups. The vaginal estrous signs were observed conspicuously in all cows examined, but the behavioral signs were not observed in 20.0% of the cows. The duration of behavioral signs (41.3 ± 23.6 h) was shorter (P<0.05) than that of the vagina (68.9 ± 25.4 h). These results imply that lactation might not interfere with the hormonal profiles from luteolysis to ovulation.
authors.affiliation: Laboratory of Veterinary Reproduction, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.
authors.forename: Natsumi
authors.initials: N
authors.lastname: Endo
authors.forename: Kiyosuke
authors.initials: K
authors.lastname: Nagai
authors.forename: Tomomi
authors.initials: T
authors.lastname: Tanaka
authors.forename: Hideo
authors.initials: H
authors.lastname: Kamomae
mesh_terms: D000818:Animals; D002417:Cattle; D004958:Estradiol / Q000097:blood*; D030762:Estrous Cycle; D005260:Female; D007774:Lactation / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood*; D003341:Luteolysis / Q000097:blood*
chemical_list: D004958:Estradiol; D007986:Luteinizing Hormone