Associations between bovine milk protein genotypes and haplotypes and the breeding value of Polish Black-and-White bulls

Abstract

One hundred forty three proven Polish Black-and-White bulls were genotyped for 6 polymorphic sites located within 4 milk protein genes (LGB-R promoter, LGB exon IV, CASK-R promoter, CASK exon IV, LALBA 5' flanking region and CSN1S1 promoter). All bulls were divided into groups, including animals with the same genotypes, intragenic haplotypes and combinations of genotypes. For each group, the arithmetic mean and standard deviation for Type Production Index (TPI) and Predicted Transmitting Ability (PTA) (milk kg, protein kg, protein %, fat kg, fat %) were calculated. These data were then used for analysis of variance to find possible associations between identified polymorphic sites and TPI and PTA values. Significant differences (P<0.01) were found within different genotypes of CASK, LGB, LALBA, intragenic haplotypes CASK/CASK-R, combinations of genotypes CASK/LALBA, CASK/LGB, LGB/LALBA, CASK/LGB/LALBA and TPI. Within these groups, the highest TPI value was found for bulls carrying the following genotypes: CASK/LGB/LALBA AA/AA/PM, CASK/LGB AA/AA, CASK/CASK-R AA/MM, LGB/LALBA AA/MM, LGB AA, CASK/LALBA AA/MM and LALBA MM. Also, associations between genotypes and combinations of genotypes and PTA for protein kg, fat kg, fat %, protein % and milk kg were found.