Abstract
Twenty boars underwent hormonal stimulation tests with GnRH. 12 blood samples within 7 hours were collected by permanent catheter. In order to consider the impact of the GnRH-doses and the reproducing of the mobilisations of LH and testosterone, two pre-tests were carried out. For the analysis of the spermatogenetic potency of the boars the routine data of native ejaculates (volume, concentration and motility) from the lab of the A. I. station were used. 17 boars had a good sperm capacity, and 3 boars fertility disturbances. Correlations between hormonal values and the parameters of the spermatogenetic potency of the boars were determined. In addition, with 3 of the 20 boars the endocrinological stimulation was coupled with a sexual strain test.
Treatment with GnRH resulted in a pronounced release of LH and testosterone in boars without fertility disturbances, with only the LH showing significant differences after 120 minutes. In the reproducing test with the same doses 4 weeks later, the boars responded with adequate hormonal mobilisations. This underlines the assumption, that a single stimulation is sufficient for a clinical study.
Treatment with GnRH resulted in an increase of LH within minutes, achieving its maximal value after 30 to 90 minutes. The release of testosterone followed 30 to 60 minutes after the GnRH treatment, in the course of which the mobilisation of testosterone under approximately homogenous conditions was very variable. Reasons could be differences in the capacity of the testosterone production of the boars.
With the help of the hormonal stimulation test functional disorders of the hypothalamic-pituitary level can be proved, without adequate morphological disorders being noticeable on the animal. It does not, however, seem suitable to differentiate boars without libido from boars with sperm deficiencies. The sole consideration of hormonal parameters permits prognostic evidence of spermatogenetic potency only of boars with extreme disorders of fertility.
With the help of the parameter "vbS/E", as average of the forwardly motile sperms per ejaculate, also A I. boars with very good spermatogenetic potency could be classified. The proportion of LH and testosterone release, designated as quotient of effectiveness (EQ), is suitable for the description of the endocrine condition of the boars.
Negative correlations of the number of forwardly motile sperms of ejaculate with the LH difference (r=-0,559) and with the maximal LH level after hormonal stimulation (r=-0.558) were found. This speaks for the thesis that LH is a suitable parameter for the assessment of the fertility.
The daily sperm output of boars can be determined by a sexually strain test, and it permits conclusions of the capacity of the germinate testicle epithelia. In conjunction with a hormonal stimulation test the variable responsiveness within the hypothalamic-pituitary-gonad system of the boars is determined. |
