Comparison of four Italian beef cattle breeds by means of functional genes

Piemontese, Chianina, Marchigiana and Romagnola are the main Italian beef breeds, and the quality of their products is largely recognised all over the world. Here, 18 single nucleotide polymorphisms (SNPs) in 12 candidate genes involved on meat traits were investigated on 1055 candidates for selection in order to analyse the within-and between-breed variability with a functional marker approach. Three SNPs (GDF8-3, GH and NPY-3) were monomorphic and most of the polymorphic SNPs showed an allele distribution quite similar in the four breeds. High variability at LEP-2, LEP-3 and LEPR markers was detected across breeds and the analysis of the relationship between genetic differentiation and heterozygosity indicated significant deviation from a neutral-equilibrium model for LEP-2. The highest pairwise fixation index values (0.1189 to 0.1877) were obtained for the comparisons of Piemontese with the other breeds, while the lowest value (0.0296) was observed in Chianina and Marchigiana. The Piemontese differentiation from the other breeds could be due to its geographical isolation and selection targets. The results for breed assignment follows the genetic differentiation, in fact, Piemontese had the highest percentage of correct assignment (87.6), while Marchigiana had the lowest (47.5). These findings suggest that functional markers can be more suitable than neutral markers in discriminating breeds similar in morphology if selection plays some role in their differentiation.