ABSTRACT:The aim of this study was to estimate allelic and genotypic frequencies of five DNA markers that are positional and functional candidates for milk production traits in Czech Fleckvieh cattle. In addition, we evaluated the association of these markers with milk production traits and breeding values for milk production traits and also estimated linkage disequilibrium (LD) between two markers within the prolactin (PRL) gene. As part of this study, 505 Czech Fleckvieh cows were genotyped. The markers in proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A), secreted phosphoprotein (SPP1), cytochrome P450 family 11 subfamily B hydroxylase (CYP11B1), and the two polymorphisms in the prolactin gene (PRL) showed evidence of segregation in our study. The PPARGC1A polymorphism was associated with milk yield, milk fat and protein traits. The polymorphism in SPP1 was significantly associated with milk protein percentage. The CYP11B1 polymorphism showed positive associations with milk composition traits and breeding values for milk yield, milk fat, and protein traits. Both polymorphisms within the PRL gene were associated with milk yield, milk fat and milk protein yield (individually and grouped). Linkage disequilibrium between the two polymorphisms in PRL was not observed. In conclusion, all markers examined in this study are important markers for milk production traits in Czech Fleckvieh cattle, and both markers within the PRL gene should be evaluated in future research.

ABSTRACT:The impact of polymorphism of the diacylglycerol acyltransferase (DGAT1), butyrophilin (BTN1A1), oxidized low-density lipoprotein receptor (OLR1), and signal transducer and activator of transcription 1 (STAT1) genes on milk production and reproduction traits in 419 Czech Fleckvieh cows was examined using polymerase chain reaction and restriction fragment length polymorphism. The loci DGAT1 and BTN1A1 were observed simultaneously to affect milk production, estimated breeding value of milk production traits, as well as reproduction parameters. Significant differences were found also between genotypes of the STAT1 loci in relation to estimated breeding value of milk production traits. Similar findings in pure dairy breeds suggest that heterogeneous effects of the observed loci can be explained by different genetic backgrounds in various breed populations selected to achieve different commercial goals. Thus, it is necessary to determine variability and influence of a molecular marker in a specific population when considering its inclusion into a breeding programme.

ABSTRACT:The aim of this study was to determine the joint effects of CSN3 and LGB genotypes on parameters of production, quality and coagulation of milk in Czech Fleckvieh cows. Three hundred and twenty-eight Czech Fleckvieh cows were determined for CSN3 (kappa-casein) and LGB (beta-lactoglobulin) genotypes using the PCR-RFLP method, milk quality parameters and coagulation properties. Milk production parameters were obtained from the Official Database of Progeny Testing. Fifteen genotype combinations were detected, with ABAB (21.0%) and AAAB (18.3%) occurring as the most frequent. The observed genes significantly affected the contents of milk protein (crude protein, true protein, casein and whey protein) as well as solid non-fat in milk, casein number and curd quality. BBAA was found to be the genotype with the highest positive impact on most of the milk characteristics evaluated. Whereas ABBB, BBBB, BBAB and ABAB had a positive influence on milk quality and milk coagulation properties, genotypes containing CSN3 allele E had a negative effect. Results presented in this study are applicable in the selection of Czech Fleckvieh cattle.

Our findings indicate that the yoghurt fermentation test together with MP genotyping could contribute to milk quality control and highlight new perspectives in dairy cattle breeding based on selecting the best animals as parents of the next generation.

Current animal breeding approaches are strongly associated with the development of sophisticated molecular genetics methods and techniques. Worldwide expansion of genomic selection can be achieved by the identification of genetic DNA markers and implementation of the microarray (“chip”) technology. Further advancement was associated with next-generation sequencing methods, high-throughput genotyping platforms, targeted genome editing techniques, and studies of epigenetic mechanisms. The remarkable development of “omics” technologies, such as genomics, epigenomics, transcriptomics, proteomics and metabolomics, has enabled individual genomic prediction of animal performance, identification of disease-causing genes and biomarkers for the prevention and treatment and overall qualitative progress in animal production.