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Polish Red cattle is one of the few indigenous breeds of European red cattle which is characterized by several desired features, such as high disease resistance, good health, longevity, good fertility, and high nutritional value of milk. Currently, Polish Red cattle population is a subject of two independent breeding programs: (i) improvement program and (ii) genetic resources conservation program. The aim of the improvement program is the genetic progress in terms of milk production and body conformation traits, while the conservation program mainly focuses on protection of the genetic resources of Polish Red cattle and preservation of the existing, original gene pool. By the analysis of F ST genetic distances across genome-wide SNP panel, we detected diversifying selection signatures among these two subpopulations and indicated (among others) the significance of DGAT1 and FGF2 genes for milk production traits in these cattle. We also found that among genes being presumably under selection in terms of milk production, there are genes responsible, for example, for mammary gland development (e.g., SOSTDC1, PYGO2, MED1, and CCND1) and immune system response (e.g., IL10RA, IL12B, and IL21). The most important finding of this study is that the most pronounced genetic differences between the analyzed populations were associated with β-defensin genes (e.g., DEFB1, DEFB4A, DEFB5, DEFB7, DEFB10, DEFB13, EBD, BNBD-6, and LAP) located within so-called bovine cluster D on BTA27. The β-defensins are expressed mainly in the mammary gland and are antimicrobial peptides against the Gram-negative and Gram-positive bacteria, viruses, and other unicellular parasites. This suggests that antimicrobial resistance of mammary gland is of high importance during selection towards increased milk production and that genes responsible for this process are selected together with increasing levels of productivity.

Controlling inbreeding in livestock populations is of great importance because excess relatedness among animals leads to a rapid loss of genetic variation and to adverse phenotypical effects associated with an inbreeding depression. Recent advances in genotyping technology have made it possible to study inbreeding at a molecular level by the analysis of genome-wide single nucleotide polymorphism panels. In this study, we used BovineSNP50 assay (Illumina) to estimate genomic inbreeding coefficient in 298 Holstein cattle by the analysis of the genome portion in runs of homozygosity (F ROH ) or using genomic relationship matrix (F GRM ), and compared this data with conventional pedigree-based inbreeding coefficients (F PED ). Weak or moderate Spearman's rank correlations were observed between F ROH and F PED which depended on the ROH length categories used for calculations and inclusion of animals with different number of complete generations registered in pedigrees. The highest correlations were observed when using ROH with lengths over 8 Mb (0.334). The correlations tended to increase as pedigree depth increased, and were the highest for animals with seven complete generations of pedigree data. F GRM correlated poorly with pedigree-based estimates, which suggests that ROH-based inbreeding coefficients better reflect recent relatedness among animals.

The study is aimed at identifying selection footprints within the genome of Limousin cattle. With the use of Extended Haplotype Homozygosity test, supplemented with correction for variation in recombination rates across the genome, we created map of selection footprints and detected 173 significant (p < 0.01) core haplotypes being potentially under positive selection. Within these regions, a number of candidate genes associated inter alia with skeletal muscle growth (GDF15, BMP7, BMP4 and TGFB3) or postmortem proteolysis and meat maturation (CAPN1 and CAPN5) were annotated. Noticeable clusters of selection footprints were detected on chromosomes 1, 4, 8 and 14, which are known to carry several quantitative trait loci for growth traits and meat quality. The study provides information about the genes and metabolic pathways potentially modified under the influence of directional selection, aimed at improving beef production characteristics in Limousin cattle., (© 2015 Blackwell Verlag GmbH.)

Copy number variation (CNV), which results from deletions or amplifications of large fragments of genomic DNA, is widespread in mammalian genomes and apart from its potential pathogenic effect it is considered as a source of natural genetic diversity. In cattle populations, this kind of genetic variability remains still insufficiently elucidated and studies focusing on the detection of new structural genomic variants in different cattle populations may contribute to a better understanding of cattle breeds' diversity and genetic basis of production traits. In this study, by using BovineSNP50 assay and cnvPartition algorithm we identified CNVs in two different cattle breeds: Holstein (859 animals) and Polish Red (301). In Holstein cattle we found 648 CNVs which could be reduced to 91 non-redundant variable genomic regions (CNVRs) covering in total 168.6 Mb of the genomic sequence. In Polish Red cattle we detected 62 CNVs, localized in 37 variable regions encompassing 22.3 Mb of the sequence, corresponding to 0.89 % of the autosomal genome. Within the regions we identified 1,192 unique RefSeq genes which are engaged in a variety of biological processes. High concordance of the regions' distribution was found between the studied breeds, however copy number variants seemed to be more common in Holstein cattle. About 26 % of the regions described in this study could be classified as newly identified. The results of this study will broaden the knowledge of CNVs in genomes of cattle of different breeds and will provide foundations for further research aiming to identify a relationship between this type of genetic variation and phenotypic traits.

Genetic improvement of animals based on artificial selection is leading to changes in the frequency of genes related to desirable production traits. The changes are reflected by the neutral, intergenic single nucleotide polymorphims (SNPs) being in long-range linkage disequilibrium with functional polymorphisms. Genome-wide SNP analysis tools designed for cattle, allow for scanning divergences in allelic frequencies between distinct breeds and thus for identification of genomic regions which were divergently selected in breeds' histories. In this study, by using Bovine SNP50 assay, we attempted to identify genomic regions showing the highest differences in allele frequencies between two distinct cattle breeds - preserved, unselected Polish Red breed and highly selected Holstein cattle. Our study revealed 19 genomic regions encompassing 55 protein-coding genes and numerous quantitative trait loci which potentially may underlie some of the phenotypic traits distinguishing the breeds., (© 2014 Japanese Society of Animal Science.)

The breed assignment in cattle is one of the issues of molecular genetics which needs further testing and development. Although several statistical approaches have been developed to enable such application, the obtained results strongly depend on specific populations differentiation and power of markers discrimination or their informativeness. Currently, all breeding animals are being tested for parentage with the use of panel of 12 microsatellite markers, which in near future probably will be replaced by about 100 single nucleotide polymorphisms (SNPs). Despite the fact that SNPs are mainly bi-allelic, the multilocus genotypes can reach the level of polymorphism of a panel of microsatellite markers. In this study we attempted to determine the breed of origin of 741 cattle by using 120 SNPs dedicated for parentage testing and included in the BovineSNP50 BeadChip genotyping assay (Illumina). The applied Bayesian and frequency-based methods allowed such differentiation, however, the reliability of the results was not completely satisfying, suggesting that the studied markers are not the best tool for breed assignment.

According to increasing interest in the use of high density SNP (single nucleotide polymorphism) genotyping assays for genome-wide genetic studies in farm animals, there is a need to assess the usefulness of currently available genomic tools for application in different breeds. The performance of the assays may differ between the breeds because of discrepancies in allele frequencies of the polymorphisms or differences in linkage disequilibrium patterns. In this study we attempted to test the performance of the Bovine SNP50 v2 genotyping assay (Illumina) for population genetic and other applications in the Polish Red cattle breed. We found that 37,977 of the 53,438 autosomal markers included in the assay give high quality genomic information and can be used for different applications concerning this breed. The remaining markers were denoted as "of limited use" or redundant because of their weak performance, deviation from Hardy-Weinberg equilibrium, low minor allele frequency, high linkage disequilibrium with other neighboring markers or location on sex chromosomes.

The aim of this study was to characterize in detail linkage disequilibrium (LD) decay and haplotype block structures in genomes of commercial Limousin (LM, n=201) and Simmental (SM, n=106) cattle and refer this data to the characteristics found in native unselected Polish Red (PR, n=299) cattle. A panel of 40,158 (LM), 40,117 (SM) and 42,118 (PR) high quality SNP (single nucleotide polymorphism) markers from Illumina BovineSNP50 v2 BeadChip were utilized for the LD analysis based on the pairwise r 2 statistic of SNPs at a distance up to 5 Mb. The lower average r 2 of 0.27 was observed in RP cattle at a short distance up to 25 kb when compared to two other studied breeds (0.3 in both LM and SM). The minimum average values of r 2 (0.01) were observed at the distances of 1500–3000 kb in LM and 3000–5000 kb in SM. In PR cattle LD persisted similarly as in SM cattle and the minimum average values of r 2 (0.02) were observed at a distance of 3000–5000 kb. The effects of minor allelic frequency threshold on the extent of LD was also evaluated by applying three different minimum MAF levels (0.05, 0.1 and 0.2). A total of 828 (LM), 667 (SM) and 761 (PR) haplotype block structures spanning 89,781 kb (LM), 72,582 kb (SM) and 70,647 kb (PR) of the genome were detected. In total, 7.92% (LM), 6.43% (SM) and 6.52% (PR) of all SNPs formed blocks with a range of 2–15 SNPs per block in LM and SM breeds and 2–16 SNPs per block in PR cattle. Mean block lengths were slightly lower in RP cattle than in two other breeds and were estimated as 108.4±99 kb, 108.8±97 kb and 92.8±87 for LM, SM and PR respectively. For all studied breeds chromosome 1 showed the longest haplotype block structures in the genome, having 66 blocks spanning 8120 kb in LM, 57 blocks spanning 6754 kb in SM and 59 blocks spanning 5920 kb in PR. The results showed slightly faster LD decay in Polish Red cattle (especially at short distances) than in two other breeds and shorter haplotype block structures which may result from population demographic history, overall genetic diversity as well as extensive breeding applied in this breed. [ABSTRACT FROM AUTHOR]