EXAMINATION OF GENETIC-LINKAGE OF QTL FOR MILK-PRODUCTION TRAITS TO MILK PROTEIN LOCI IN A FAMILY ANALYSIS COMPARED WITH RESULTS OF A POPULATION ANALYSIS

Milk performances and genotypic information of daughters of sires bein g heterozygous at minimum two milk protein loci used as markers were e xamined in a Segregation and linkage analysis of single families under lying the mixed model of inheritance. The recombination rate was estim ated to be 0 for protein content and protein to fat ratio and P-Lactog lobulin. LOD scores amounted to 2.57 and 1.40 in one out of five famil ies. The analysis with K-Casein and protein content resulted in LOD sc ore > 1 and an estimated recombination rate theta = 0.31. The results obtained are discussed together with those of a population analysis. A significant evidence for medium linkage in case of K-Casein and a QTL for fat yield (theta = 0.25, LOD score 3.03) was gained in the popula tion analysis. The QTL effects are far from the high statistical certa inty which was gained by the population analysis.