A clear negative effect of the warm period on reproductive performance was noted.Table 1shows the results obtained during the warm and cold period. Thus, the pregnancy rate to first AI was 12% (7/60) and 21% (14/68), for the GPG and GPH-treated groups, respectively, there being no significant differences between groups. The cumulative pregnancy rate was 22% (13/60) and 21% (14/68) for the GPG and GPH groups, respectively, again with no significant intergroup differences.