Evaluation of the GnRH test results of beef-type breeding bull candidates

The GnRH test results of Hungarian Fleckvieh and Charolais breeding bull candidates were evaluated by two different methods (selection based on previously fixed standard data and on standard deviation, respectively) in two breeding herds. The Leydig's cell response of the testicles to a central signal after the injection of a single dose of 100 micrograms exogenous GnRH analogue (Ovurelin inj. ad us. vet., Reanal Co. Ltd., Budapest) was evaluated. The two different selection methods used for evaluating the results of the GnRH test brought different results: on the basis of phenotypic value three, while according to the absolute value seven Hungarian Fleckvieh individuals were selected as excellent. For the evaluation of the results of GnRH treatment, the phenotypic deviation value should be used in the practice because of its easy interpretation. The relative phenotypic values changed between 84.4 and 136.6 in the Hungarian Fleckvieh and between 64.7 and 179.4 in the Charolais breed.