Number of oocytes obtained from cows by OPU in early, but not late lactation increased with plasma insulin and estradiol concentrations and expression of mRNA of the FSH receptor in granulosa cells

N. Argov, A. Arav*, D. Sklan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

The effects of lactation stage and hormonal profile on the quality and quantity of oocytes and the gonadotrophic sensitivity of granulosa cells (GC) from small antral follicles obtained by sequential aspirations from ovaries of high producing dairy cows were examined. Cows in late lactation (263(±60) days postpartum) and 98(±16) days pregnant in positive energy balance (EB) showed no significant changes in plasma concentrations of estradiol, progesterone, insulin, IGF1 or expression of mRNA of the FSH receptor in GC from small antral follicles during the 49 days experimental period. There were no changes in the number and quality of oocytes obtained from each aspiration. In cows in early lactation (72.8±6 days postpartum), plasma insulin concentrations increased and were positively correlated with plasma estradiol concentration. Due to the sequential aspirations progesterone blood concentrations were low in early lactation cows. Expression of mRNA of the FSH receptor increased in GC from small antral follicles of early lactation cows together with the number of oocytes obtained with aspiration sessions. No differences were found in morphological quality or function between oocytes obtained from small antral follicles from cows in early or late lactation. In early, but not late lactation, the number of oocytes was correlated with both insulin and E2 plasma concentrations. Improved EB and sensitivity of GC to FSH may be involved in oocyte recruitment in early lactation.

Original languageAmerican English
Pages (from-to)947-962
Number of pages16
JournalTheriogenology
Volume61
Issue number5
DOIs
StatePublished - 1 Apr 2004

Bibliographical note

Funding Information:
This study was supported in part by a grant from the Israeli Milk Marketing Board.

Keywords

  • Follicular development
  • Lactation stage
  • Oocyte
  • Steroidogenesis

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