The study investigated the relationship between estrus intensity and conception rates in dairy cows and heifers as well as between the level of physical constitution and conception rates in cows measured on the day of artificial insemination (AI). Females were submitted for AI after confirming standing estrus, and just prior to insemination the estrus intensity was investigated and classified as strong if three out of four factors were detected i.e. standing, vaginal mucus discharge, high uterine tone or presence of follicles in the ovaries; otherwise the estrus intensity was classified as weak. In the cow’s group (n=48) only those exhibiting estrus between 50 and 100 days following delivery were investigated and only heifers (n=42) that were approximately 18 months old were inseminated. No drugs were administrated for oestrus synchronisation. The study indicated that oestrus intensity had no effect on conception rates in cows (58% vs. 45% cows exhibiting strong and weak oestrus respectively were pregnant) but oestrus intensity did affect the conception rates in heifers (78% vs. 47% heifers exhibiting strong and weak oestrus respectively were pregnant, p<0.05). The physical constitution level measured on the day of AI had no effect on conception rates and was similar in both pregnant and non pregnant cows (3.20 ± 0.18 and 3.31 ± 0.33 respectively).
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