title: Effect of different stages of the follicular wave on in vitro developmental competence of bovine oocytes.
abstract: This study aimed to investigate the developmental competence of ovum pick-up collected oocytes on three stages of the follicular wave: Days 2, 5 and 8. A group of 11 cows was used in successive cycles to perform ovum pick-up on either Day 2, 5 or 8 of an induced follicular wave (three sessions per stage). Follicular waves were initiated by puncturing the dominant follicle and all other follicles sized > or = 5 mm at Days 5-7 of the cycle. The plasma progesterone concentrations did not differ between the days of ovum pick-up: 4.0 +/- 1.8, 5.1 +/- 1.6 and 5.2 +/- 1.7 ng/ml for Days 2, 5 and 8, respectively. The proportion of oocytes with three or more layers of non-expanded cumulus cells was higher for Day 5 than Day 8, while Days 2 and 5 did not significantly differ from each other (85, 96 and 68% of 113, 60 and 101 oocytes for Days 2, 5 and 8, respectively). The proportion of oocytes competent to develop a blastocyst in an in vitro production system was higher for Days 2 and 5 than for Day 8: 27, 29 and 15% for the oocytes with fair to good cumulus investment and 23, 27 and 11%, respectively, when all oocytes were taken in account. This indicates that the dominant follicle reduces the developmental competence of oocytes from subordinate follicles at a relatively late stage of dominance. This finding has practical consequences for the handling of cows that undergo ovum pick-up only once or very irregularly. The embryo yield can then be improved by performing the ovum pick-up at Days 2-5 of the cycle or 2-5 days after ablation of the large follicles.
authors.affiliation: Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan, The Netherlands. p.hedriksen@erasmusmc.nl
authors.forename: P J M
authors.initials: PJ
authors.lastname: Hendriksen
authors.forename: W N M
authors.initials: WN
authors.lastname: Steenweg
authors.forename: J C
authors.initials: JC
authors.lastname: Harkema
authors.forename: J S
authors.initials: JS
authors.lastname: Merton
authors.forename: M M
authors.initials: MM
authors.lastname: Bevers
authors.forename: P L A M
authors.initials: PL
authors.lastname: Vos
authors.forename: S J
authors.initials: SJ
authors.lastname: Dieleman
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology; D002417:Cattle / Q000502:physiology*; D002478:Cells, Cultured; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D009865:Oocytes / Q000254:growth & development*; D006080:Ovarian Follicle / Q000000981:diagnostic imaging / Q000502:physiology*; D011374:Progesterone / Q000097:blood; D011677:Punctures; D014463:Ultrasonography
chemical_list: D011374:Progesterone