Genetic differences among native and modern cattle breeds in Lithuania based on milk protein loci polymorphism.

The intrabreed and interbreed genetic diversity of Lithuanian cattle breeds - two native, namely Lithuanian Light Grey and Lithuanian White-Backed and two modern, namely Lithuanian Red and Lithuanian Black and White was investigated by determination of genetic markers: 4 milk protein systems, Alpha(s1)-casein, Kappa-casein, Beta-casein and Beta-lactoglobulin, which are comprised of 12 different milk protein types. According to results, the B type of Alpha(s1)-casein was found as predominant in all four studied breeds. The most common A and B types of Kappa-casein were found at high frequency in all investigated cattle breeds. All investigated Lithuanian dairy cattle breeds had high frequency of Beta-lactoglobulin whey protein B types, with the highest frequency in Lithuanian Red breed, and the lowest in Lithuanian Light Grey. After investigation the diversity of alleles and genotypes of milk proteins in Lithuanian dairy cattle breeds was determined that, Lithuanian Red breed was distinguished private C allele and BC genotype of Beta-lactoglobulin and CC genotype of Alpha(s1)-casein. The interbreed genetic diversity was estimated by a principal component analysis (PCA). The first principal component (PC) explains 63.39% and the second principal component (PC) explains 33.67% of the genetics diversity between the breeds. Principal component analysis, suggests the hypothesis that native Lithuanian White Backed and Lithuanian Light Grey breeds still have traits tracing to old native populations.

Prioritization for conservation of northern European cattle breeds based on analysis of microsatellite data.

Northern European indigenous cattle breeds are currently endangered and at a risk of becoming extinct. We analyzed variation at 20 microsatellite loci in 23 indigenous, 3 old imported, and 9 modern commercial cattle breeds that are presently distributed in northern Europe. We measured the breeds' allelic richness and heterozygosity, and studied their genetic relationships with a neighbor-joining tree based on the Chord genetic distance matrix. We used the Weitzman approach and the core set diversity measure of Eding et al. (2002) to quantify the contribution of each breed to the maximum amount of genetic diversity and to identify breeds important for the conservation of genetic diversity. We defined 11 breeds as a "safe set" of breeds (not endangered) and estimated a reduction in genetic diversity if all nonsafe (endangered) breeds were lost. We then calculated the increase in genetic diversity by adding one by one each of the nonsafe breeds to the safe set (the safe-set-plus-one approach). The neighbor-joining tree grouped the northern European cattle breeds into Black-and-White type, Baltic Red, and Nordic cattle groups. Väne cattle, Bohus Poll, and Danish Jersey had the highest relative contribution to the maximum amount of genetic diversity when the diversity was quantified by the Weitzman diversity measure. These breeds not only showed phylogenetic distinctiveness but also low within-population variation. When the Eding et al. method was applied, Eastern Finncattle and Lithuanian White Backed cattle contributed most of the genetic variation. If the loss of the nonsafe set of breeds happens, the reduction in genetic diversity would be substantial (72%) based on the Weitzman approach, but relatively small (1.81%) based on the Eding et al. method. The safe set contained only 66% of the observed microsatellite alleles. The safe-set-plus-one approach indicated that Bohus Poll and Väne cattle contributed most to the Weitzman diversity, whereas the Eastern Finncattle contribution was the highest according to the Eding et al. method. Our results indicate that both methods of Weitzman and Eding et al. recognize the importance of local populations as a valuable resource of genetic variation.

Detection of prion protein gene polymorphisms in Baltic breeds of sheep.

A total of 167 sheep belonging to the Estonian whiteheaded mutton, Estonian blackheaded mutton, Lithuanian coarsewool native, Lithuanian blackface and Latvian darkheaded mutton breeds, and a population of sheep kept isolated on the Estonian island of Ruhnu, were sequence-analysed for polymorphisms in the prion protein (PrP) gene, to determine their genotype and the allele frequencies of polymorphisms in PrP known to confer resistance to scrapie. A 939 base pair fragment of exon 3 from the PrP gene was amplified by pcr and analysed by direct sequencing. For animals showing polymorphism at two nucleotide positions, both haplotypes of these double-heterozygous genotypes were further verified by pcr cloning and sequence analysis. Known polymorphisms were observed at codons 136, 154 and 171, and six different haplotypes (arr, ahq, arh, ahr, arq and vrq) were determined. On the basis of these polymorphisms, the six populations of sheep possessed the resistant arr haplotype at different frequencies. The high-risk arq haplotype occurred in high frequencies in all six populations, but vrq, the haplotype carrying the highest risk, occurred at low frequencies and in only three of the populations.

Twins rate in the black-and-white cattle population in Lithuania.

Obtaining the maximal number of calves from each cow according to its natural genetic reproduction ability is the main condition of intensification of reproduction and increase of milk production. Twins rate in the black-and-white cattle population in Lithuania is 2.4%. Cows whose mothers have calved twins at least 1 time during reproductive life have twins in 5.6% of all calvings, the others--in 1.9%. Twins rate in separate bulls daughters range from 1% to 6.1%. Twins rate in cows range from 0.4% to 5% by separate bulls-getters. Productivity of 305 days lactation after having twins is better (551.2+/-68.1 kg of milk, 18.4 +/-2.9 kg of fat and 21.5+/-2.4 kg of protein, P < 0.001). The rate of twin births increases when lactation is increased. The influence of lactation on rate of twin births is 0.6% in total dispersion (P < 0.001). The influence of calving season on twins rate is statistically insignificant but the parts of twins by calving seasons are distributed differently.

Native breeds demonstrate high contributions to the molecular variation in northern European sheep.

Population contribution to genetic diversity can be estimated using neutral variation. However, population expansion or hybridization of diverged ancestries may weaken correlation between neutral and non-neutral variation. Microsatellite variation was studied at 25 loci in 20 native and 12 modern or imported northern European sheep breeds. Breed contributions to total gene diversity, allelic richness and mean allele-sharing distance between individuals were measured. Indications of changes in population size and admixtures of divergent ancestries were investigated and the extent of inbreeding was estimated. The northern European sheep demonstrated signs of reduction in effective population size. Many old, small populations made a substantial positive contribution to total molecular variation, but populations with several divergent major ancestries did not contribute substantially to molecular variation, with the exception of the Norwegian Rygja sheep. However, several diverged major ancestries may cause it to contribute less to non-neutral variation than expected from the microsatellite data. Breed uniqueness and within-breed variability generally had opposite effects on breed contributions to molecular diversity. The degree of inbreeding did not reflect the breed contribution to total gene diversity or allelic richness, but inbred populations increased the mean allele-sharing distance between individuals. Our study indicates breed conservation to be especially important in maintaining allelic variation in northern European sheep and supports the evolutionary importance of peripheral populations.

Unfolding of population structure in Baltic sheep breeds using microsatellite analysis.

Studies of domestic animals are performed on breeds, but a breed does not necessarily equate to a genetically defined population. The division of sheep from three native and four modern Baltic sheep breeds was studied using 21 microsatellite loci and applying a Bayesian clustering method. A traditional breed-wise approach was compared to that relying on the pattern of molecular diversity. In this study, a breed was found to be inconsistent with a distinct genetic population for three reasons: (i) a lack of differentiation between modern Baltic breeds, since the majority of the studied sheep formed a single population; (ii) the presence of individuals of foreign ancestry within the breed; and (iii) an undefined local Saaremaa sheep was referred to as a breed, but was shown to consist of separate populations. In the breed-wise approach, only the clearly distinct Ruhnu sheep demonstrated low within-breed variation, although the newly identified Saaremaa populations also have low variability. Providing adequate management recommendations for the Saaremaa sheep is not possible without further studies, but the potential harmful effects of inbreeding in the Ruhnu sheep could be reduced through the use of two genetically related Saaremaa populations. In other breeds, excessive crossing appears to be a larger concern than inbreeding. Assigning individuals into populations based on the pattern of genetic diversity offers potentially unbiased means of elucidating the genetic population structure of species. Combining these genetic populations with phenotypic and aetiological data will enable formulation of the most informed recommendations for gene resource management.

Comparison of microsatellite and blood protein diversity in sheep: inconsistencies in fragmented breeds.

Finnsheep, Romanov, Oxford Down and three local breeds from Finland or northwestern Russia were assessed at 15 microsatellite and 7 protein loci. A novel albumin allele was identified. Diversity patterns were mostly concordant between marker types, but discrepancies appeared for the local Viena and Vepsia sheep, both demonstrating frequent linkage disequilibria for both marker types and excess of homozygotes for microsatellites, and in the case of Vepsia also for proteins as signs of breed fragmentation. On the basis of microsatellite data, the neighbour-joining tree and two-dimensional map constructed from DA distances suggested that difference in longitude of breed origin would relate to breed relationship, whereas on the basis of protein data latitude would have this quality. These different impressions resulted because genetic distances involving Vepsia sheep were relatively low for protein variation compared with microsatellites. Microsatellite variation correlated positively with protein variation, but for the local Viena sheep protein variation was comparatively low. Populations had significant differences in allelic richness, but not in genetic diversity. Analysis implied that at least 30 polymorphic loci were needed to detect a difference in diversity between populations using a paired t-test, if the true mean diversity difference was 0.2. In the total sample, proteins demonstrated larger theta-values, but this was reversed for Finnsheep, for which model-based clustering of microsatellite genotypes revealed a structure associated with coat colour. Imported and rare sheep exhibited lowered allelic variability and increased frequency of pairwise disequilibria between unlinked markers. Our results emphasize that more loci are required for studying fragmented breeds.