CROSSBREEDING EFFECTS IN THE DEVELOPMENT OF THE SYNTHETIC BLACK-AND-WHITE (SMR) DAIRY-CATTLE IN EAST-GERMANY

This paper gives an overview of some important results about the crossing of Jersey (J) with Black and White cattle (BW) in East Germany. The utilization of the J as a crossing partner for BWs leads to heterosis effects. Given the production conditions of the early GDR, the percent heterosis effect for milk fat production was about 7.5%. In contrast to the BWs, the second generation of inter-se mating of Black and White dairy cattle of the GDR (=SMR) showed an increase in heritability, especially with regards to milk yield. At the same time, modified heritabilities, particularly for milk fat and milk protein content within F1-crossing J x BW are demonstrated. Moreover, a very strong negative correlation could be observed between milk yield and milk protein content in the Jersey crossings, particularly in the SMRs.