A total number of 2274 oocytes were collected
and matured in vitro, 1135 were fertilized with six
different Holstein bulls and 1139 with six different
Brown Swiss bulls. Oocytes collected from each batch of
ovaries were divided and assigned to the crossbred or
purebred group to reduce the effect of the oocyte quality.
We found no difference in cleavage rate at 30 h (28.78 vs
26.41%) and in total cleavage rate (78.79 vs 74.35%),
although we observed a significant difference in favor
of crossbred embryos in the compaction rate on day 6
(26.5 vs 30.03%; PZ0.01) and a tendency for higher
blastocyst development on day 7 (18.93 vs 20.89%) and
8 (29.18 vs 33.18%; PZ0.07, c2 test). Results are
summarized in Table 1.