Milk from domestic cows has been a valuable food source for over 8,000 years, especially in lactose-tolerant human societies that exploit dairy breeds. We studied geographic patterns of variation in genes encoding the six most important milk proteins in 70 native European cattle breeds. We found substantial geographic coincidence between high diversity in cattle milk genes, locations of the European Neolithic cattle farming sites (>5,000 years ago) and present-day lactose tolerance in Europeans. This suggests a gene-culture coevolution between cattle and humans.

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The aim of the study is focused on the design of a conservation sheep breeding programme for the studied autochthonous breeds based on SSR markers genetic variation analysis applied. Seven local Bulgarian autochthonous sheep breeds (Breznishka, Sofiiska, Copper-Red Shumenska, Karakachanska, Local Karnobatska, Blackhead Plevenska and Starozagorska) were differentiated using six microsatellite (SSR) markers, aiming to assess the genetic variation within and between breeds. Among the total of 96 identified alleles, eighteen population specific ones were detected across the all studied genotypes of 338 individuals, except in the Blackhead Plevenska sheep. All examined breeds indicated high level of genetic diversity, with an average of 0.792. The genetic differentiation between the examined sheep breeds was not significant and the values of genetic distances were relatively low. The analysis of molecular variances (AMOVA) showed low variation between the examined breeds (5.51%) in comparison to within population variation (94.49%). The greatest distance (0.643) was found between the populations Local Karnobatska and Starozagorska, while the smallest one (0.108), between the Copper-Red Shumenska and Karakachanska. The genetic distances calculated by Neighbour-Joining method, produced a phylogenetic tree which separates the investigated sheep breeds into two main clusters: one including Blackhead Plevenska Breznishka and Local Karnobatska, and the other one consisting of the four remaining breeds - Copper-Red Shumenska, Karakachanska, Sofiiska and Starozagorska sheep. The Factorial Correspondence Analysis (FCA) showed isolation of Local Karnobatska sheep and Starozagorska and an admixture of the other populations.