title: Relationships between changes in plasma concentrations of leptin before and after parturition and the timing of first post-partum ovulation in high-producing Holstein dairy cows.
abstract: During early lactation, dairy cattle are in negative energy balance and the delay to first post-partum ovulation depends on the time taken to recover from this situation. Lactating cows rely heavily on body fat to meet their requirements, leading to the suggestion that leptin, a hormone secreted mainly by adipocytes, is acting as a metabolic signal to sites that control the reproductive axis. The relationship between plasma leptin concentrations and the timing of the first ovulation post partum in 20 high-producing Holstein dairy cows, using a radioimmunoassay based on recombinant bovine leptin was studied. Plasma leptin concentrations declined after parturition, reached a nadir of 0.74 +/- 0.17 ng mL(-1) on 10.1 +/- 2.2 days after parturition (all values are mean +/- SEM). They then increased and became stable near the time of ovulation. Leptin concentrations averaged 1.81 +/- 0.31 ng mL(-1) in the 14 days prepartum, 1.32 +/- 0.21 ng mL(-1) in the post-partum preovulatory period and 1.61 +/- 0.24 ng mL(-1) in the post-ovulatory period. The differences between periods were significant (P<0.01). The interval from parturition to first ovulation averaged 25.9 +/- 2.0 days and was not correlated with the prepartum, preovulatory or post-ovulatory leptin values. However, the interval to first ovulation correlated significantly (r = 0.83 P < 0.0001) with the interval from parturition to the leptin nadir. These results show that plasma concentrations of leptin decrease in dairy cows in the early post-partum period and suggest that a delay in the recovery of leptin secretion increases the delay to the first ovulation.
authors.affiliation: Department of Animal Production, Hokkaido National Agricultural Experiment Station, Toyohira, Sapporo, Japan. hiroya@cryo.affrc.go.jp
authors.forename: H
authors.initials: H
authors.lastname: Kadokawa
authors.forename: D
authors.initials: D
authors.lastname: Blache
authors.forename: Y
authors.initials: Y
authors.lastname: Yamada
authors.forename: G B
authors.initials: GB
authors.lastname: Martin
mesh_terms: D000273:Adipose Tissue / Q000502:physiology; D000818:Animals; D002417:Cattle; D004435:Eating / Q000502:physiology; D004734:Energy Metabolism; D005260:Female; D007743:Labor, Obstetric / Q000097:blood*; D007774:Lactation / Q000097:blood*; D020738:Leptin / Q000097:blood*; D010060:Ovulation / Q000097:blood*; D049590:Postpartum Period / Q000097:blood; D011247:Pregnancy; D013997:Time Factors
chemical_list: D020738:Leptin