title: Overall efficiency of in vitro embryo production and vitrification in cattle.
abstract: In 5 replicates a total of 719 immature oocytes recovered from 94 slaughterhouse-derived bovine ovaries were matured and fertilized in vitro, then cultured for 7 to 9 d on a granulosa cell monolayer in TCM 199 supplemented with calf serum. Of 338 blastocysts (47% of oocytes cultured), 301 were vitrified in Hepes/bicarbonate buffered TCM-199 medium, 20% calf serum and dimethylsulfoxide and ethylene glycol as the cryoprotectants. After thawing in 1 M sucrose and subsequent culture in vitro, 237 (79%) of the blastocysts re-expanded and 177 (59%) hatched. Re-expansion and hatching rates differed between the blastocysts vitrified on Day 7 and Day 8 (84 and 69% vs 70 and 41%, respectively). We conclude that the applied methods are relatively simple and inexpensive to use, with an overall efficiency of the in vitro production/vitrification procedure being 1.9 hatched blastocyst/ovary. Therefore, this system seems suitable for large-scale production of cryopreserved bovine embryos for various purposes.
authors.affiliation: Embryo Technology Center, Danish Institute of Animal Science, DK-8830 Tjele, Denmark.
authors.forename: G
authors.initials: G
authors.lastname: Vajta
authors.forename: P
authors.initials: P
authors.lastname: Holm
authors.forename: T
authors.initials: T
authors.lastname: Greve
authors.forename: H
authors.initials: H
authors.lastname: Callesen