[Evaluation of environmental factors on the fertility of heifers]

The investigations had the aim to find out the environmental influences upon the fertility performance of 8100 heifers in a big heifers farm. The different reproductive parameters were evaluated by the help of biostatistical methods. The evaluation of the different influences showed no effect in the relation of fertility and nutrition and fertility and seasonality. The check up by the help of the regression analysis and the analysis of variance informed about significant influences by the number of animals per group, by the keeping conditions and by the induction of ovulation. The induction of ovulation by GnRH is able to terminize the time of ovulation. Therefore it is possible to concretisize the insemination time followed by an increasing conception rate.