Abstract

The present study was conducted to evaluate sire effect on the kinetics of in vitro cleavage and further embryonic development after in vitro fertilization (IVF) using bulls of an Azorean rare breed called “Ramo Grande” (RG), and examine whether a relationship exists between bull's sperm apoptosis and sire in vitro fertility. Results showed that cleavage and blastocyst rates were statistically different between bulls (P<.05), being possible to notice different ability to produce embryos with good development competence (P<.05), as assessed by the proportion of fertilized oocytes that reached blastocyst stage. The proportion of blastocysts that continued the development to hatched blastocysts stage ranged from 9.1 to 87.5% (P<.05). Differences in sperm apoptosis increased during the swim-up procedure, which was statistically different (P<.05) between bulls, being negatively correlated with the ability of those bulls to fertilize oocytes and resulting embryos to develop to hatched blastocysts (R=0.96, P.01). In conclusion, this study clearly demonstrated great differences between bulls, concerning apoptosis levels, which were negatively related to bull's ability to produce good quality embryos after IVF.