Title:Friss-hűtött és fagyasztott spermával végzett termékenyítések tapasztalatai kancákban
SUMMARY Background: Cryopreservation supports very much the application of AI in the horse breeding, like in other farm animal species.Objectives: The objective of this study was to compare the efficiency of AI car-ried out with frozen and fresh cooled semen under field condition. One hundred twenty-nine mares of different breeds and age were involved in the study. All inseminations were carried out by the same veterinarian in the breeding season.Results and Discussion: Out of the 107 mares inseminated with fresh chilled semen, 81 mares got pregnant (81/107; 75.7%) and gave birth to 74 foals (74/81; 91.4%). Out of the 22 mares inseminated with frozen semen, 17 mares got pregnant (17/22; 77.3%), and finally 15 healthy foals were born (15/17; 88.2%). In the ratio of mares became pregnant and the foals born no significant differences were found between the two groups (p > 0.05). Authors didn’t found difference in the comparison of medians neither for the number of insemination cycles nor for the length of service period and days to conception. They found significant difference (p = 0.014) for the number of the insemination per conception in favour of frozen semen (2.5 vs. 1.8 with fresh cooled and frozen semen, respectively).The Cox-regression revealed that the type of semen has a significant impact (p < 0.001) to the service period. The negative beta value (–1.1156) for semen type means that the frozen semen makes the length of insemination period longer. It could be due to management issues, the repeated breeding with frozen semen took place only after one/few missed (not used) oestrus cycles.