The goal of this study was to determine the effects of heat stress on embryo development (measured as blastocyst
rate), quality (measured as rate of apoptosis and level of expression of stress- and survival-related genes), and
pregnancy establishment success of Bos taurus (Jersey and Angus) and Bos indicus embryos (Nellore). Our hypothesis
was that Nellore (Bos indicus) embryos are affected less by heat stress than are Angus and Jersey (Bos taurus) embryos.