Approaches for the analysis of genetic diversity in cattle breeds farmed in Italy

The Melanocortin 1 receptor (MC1R) is one of the main genes implicated in the determination of the coat colour in mammals. This locus showed a relevant genetic variation between breeds that can be exploited for breed traceability of the animal productions. Modicana, Cinisara and Sardo-Modicana are three Italian cattle breeds. Genetic characterization by molecular markers is a fundamental prerequisite for managing genetic resources and for developing potential genetic traceability protocols. In order to improve the knowledge on Modicana, Cinisara and Sardo-Modicana breeds and to evaluate the possibility to develop DNA-based protocols for their mono-breeds products traceability, the genetic structure of MC1R gene was analysed. Over the last fifty years, cattle breeds have been subjected to intense artificial selection. Consequently, regions controlling traits of economic importance are expected to exhibit selection signatures. The fixation index (Fst) is an estimate of population differentiation, based on genetic polymorphism data. It is calculated using the relationship between inbreeding and heterozygosity. Fst and observed heterozygosity were calculated for SNPs randomly distributed across the genome in Italian Brown and Piedmontese bulls. Then, both Fst and Het were fitted with a Locally Weighted Scatterplot Smoothing (LOWESS) regression to yield chromosomal smoothed patterns. Finally, statistical significance of Fst values was assessed by using a control chart.