GENETIC-ANALYSIS OF MORPHOLOGIC TRAITS OF TESTICLES AND THEIR CORRELATIONS TO PATERNAL NON-RETURN-RATE AS WELL AS TO GROWTH AND CARCASS TRAITS IN GERMAN SIMMENTAL

Morphological traits of testicles were investigated in 10 progeny grou ps each consisting of 8 bulls of the breed German Simmental. The bulls had undergone the progeny test for growth and carcass traits and were slaughtered at an age of 500 pays. The weight of the average of both testicles amounted to 350 +/- 54 g, the length of the testicles was 12 9 +/- 8 mm, the width of testicle was 71 +/- 4 mm, the circumference o f testicle was 205 +/- 12 mm and the volume of the testicular parenchy m was 287 +/- 47 cm(3). Per tubular diameter there were counted 16.5 /- 0.6 Sertoli cells, 2.6 +/- 0.4 A-spermatogonia and 11.2 +/- 0.7 B-s permatogonia. The heritability estimates in a half sib analysis were l ow to medium. A significant positive correlation was found between the volume of the testicular parenchym and the breeding values for the pa ternal Non-Return-Rate 90 days after first insemination (NR90). Howeve r, no significant relationships could be established between the breed ing values for the paternal NR90 and the number of the different cell types per tubular diameter of the germ cell cycle. The breeding values for growth rate and carcass quality showed no significant correlation s to all testicular traits examined. The results found may be conclude d that the total number of Sertoli cells and spermatogonia cells may c ause the positive genetic correlation among paternal fertility and tes ticular parenchym, whereas differences in germ cell maturation among s ires seem to be of minor importance for paternal insemination results. It can be supposed that genetic differences in releasing and action o f gonadotropins may exist and these may be responsible for the positiv e genetic correlation among paternal NR90 and testicular parenchym.