Variability in major milk protein genes in two autochthonous cattle breeds mainly reared in the Parmigiano-Reggiano cheese production area: Reggiana and Modenese

Reggiana and Modenese (also known as Bianca Valpadana) are two iconic autochthonous cattle breeds mainly raised in the North of Italy, in the area where the Protected Designation of Origin Parmigiano-Reggiano cheese is produced. The monitoring of diffusion of milk protein gene variants in these cattle breeds is important to evaluate the impact of selection and conservation programs on the frequency of favourable alleles on milk quality and cheese-making properties and to avoid the increase of the frequency of alleles with unfavourable effects. In this study, we genotyped a total of ∼3,300 cattle of the Reggiana and Modenese breeds with the GeneSeek® Genomic Profiler™ Bovine 150 K Array and obtained an updated picture of the variability present in three milk protein genes (CSN2, CSN3 and PAEP, also known as β-lactoglobulin). We then retrospectively evaluated the trend of allele frequency changes over time, going back ∼50 years, comparing the information reported by previous studies in the same two breeds. The allele frequency trends could be considered either positive, according to the increase in frequency of alleles with favorable effects on cheese making properties and cheese yield (i.e., CSN3*B in both breeds) or negative, based on the decrease in frequency of favorable alleles on the same traits (i.e., PAEP*B in Reggiana). Therefore, some adjustments in the selection and conservation programs might be needed to maintain genetic properties that can positively contribute to addressing the production of high-quality Parmigiano-Reggiano cheese and support a sustainable conservation of these cattle genetic resources.