EN
The aim of the study was to establish the correlation between energy balance disturbances and the effectiveness of the induction of ovulation in mares in foal heat. The investigation was carried out on 90 thoroughbred mares, which were divided in two groups on 45 animals: A - induced ovulation, B - spontaneous ovulation. During foal heat, concentrations of glucose, β-hydroxybutyrate and free fatty acids were determined. On the basis of their biochemical status mares were divided in two subgroups: with and without energy balance disturbances. At the follicle diameter of 40 mm the mares received either 40 µg GnRH- analogue (buserelin) or 10 ml saline solution. Ovulation occurred within 48 hours in 31% mares with energy balance disturbances and 62.5% without energy balance disturbances (p ≤ 0.001). Fertility performance was significantly higher in mares without energy balance disturbances (p ≤ 0.001).