title: Fertilizability of oocytes derived from Holstein cows having different antral follicle counts in ovaries.
abstract: In this study, to clarify the relationship between ovarian reserve and oocyte quality, cumulus-oocyte complexes (COCs) were collected repeatedly by ovum pick-up (OPU) from cows with high and low antral follicle counts (AFCs) at short (3-4 days) and long (7 days) intervals, and COC morphologies and oocyte fertilizability were examined. The relationship between AFC and follicular growth after OPU was also investigated. Cows showing AFC of ≥30 in at least one OPU session were grouped into the high-AFC group. At a short interval, follicular sizes and COC morphologies were similar between the different AFC groups. However, the normal fertilization rate was higher in the high-AFC group than in the low one, although total penetration rates were similar. At a long interval, the percentage of COCs with poor morphology in the high-AFC group was higher and the normal fertilization rate was lower than in the low one. In the low-AFC group, normal fertilization rates at short and long intervals were similar, and mean follicular size became larger at a long than at a short interval. However, mean follicular sizes at short- and long-interval OPU were similar in the high-AFC group. In conclusion, it is suggested that oocytes derived from cows with high AFC had higher fertilizability than those from cows with low AFC when OPUs were performed at a short (3-4 days) interval. However, oocyte quality in high-AFC cows was impaired by long-interval (7 days) OPU, possibly due to the degradation of follicles.
authors.affiliation: Laboratory of Theriogenology, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Nagai
authors.affiliation: Laboratory of Theriogenology, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
authors.forename: Yojiro
authors.initials: Y
authors.lastname: Yanagawa
authors.affiliation: Laboratory of Theriogenology, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan; Laboratory of Theriogenology, Department of Large Animal Clinical Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu 069-8501, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Katagiri
authors.affiliation: Laboratory of Theriogenology, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan. Electronic address: mnaga@vetmed.hokudai.ac.jp.
authors.forename: Masashi
authors.initials: M
authors.lastname: Nagano
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary*; D009865:Oocytes / Q000502:physiology*; D006080:Ovarian Follicle / Q000502:physiology*
keywords: Antral follicle count; Dairy cattle; Oocyte quality; Ovarian reserve; Ovum pick-up