Abstract
The present study was carried out to investigate the effect of glucose on the development of bovine embryos fertilized in vitro up to the blastocyst stage using CR1aa medium.
In vitro fertilized ova were randomly assigned to 4 groups and then these were co-cultured with cumulus cells for 8 days. The groups were 1) CRlaa + 2% calf serum (CS); 2) CR1aa + 2% CS + 0.1 mM glucose (day 0 to 3), then CRlaa + 2% CS (day 3 to 8); 3) CR1aa + 2% CS + 0.1 mM glucose (day 0 to 8); 4) CRlaa + 2% CS (day 0 to 3), then CR1aa + 2% CS + 0.1 mM glucose (day 3 to 8).
Developmental rate up to the blastocyst stage of the group cultured in CR1aa + 2% CS + 0.1 mM glucose from day 3 to day 8 was higher (P<0.05) than the other culture groups.
In the second experiment in vitro fertilized ova were co-cultured with cumulus cells in CRlaa + 2% CS (day 0 to 3), and further cultured for 7 days in CR1aa + 2% CS + 5 different glucose levels (0 mM, 0.1 mM, 0.5 mM, 1.0 mM, 10 mM or 20 mM).
In the three levels of glucose (0.1 mM, 0.5 mM and 1.0 mM) development rates up to the hatching blastocyst stage (11.5, 17.4 and 17.2%, respectively) at day 10 were higher (P<0.05) than in the 0 mM level (5.6%). Two high levels of glucose (10mM and 20 mM) reduced significantly the rate of blastocyst development (2.2 and 0%, at day 7).
This study demonstrates that 0.1 mM1.0 mM levels of glucose in CRlaa + 2% CS from day 3 to day 10 in co-culture with cumulus cells are beneficial to bovine embryo development to the hatching blastocyst stage.
