Frequencies Evaluation of β-Casein Gene Polymorphisms in Dairy Cows Reared in Central Italy
Istituto Zooprofilattico Sperimentale dell’Umbria e delle Marche-Togo Rosati (IZSUM), Via Salvemini 1, 06126 Perugia, Italy
R&D Cooperlat, Società Cooperativa Agricola, via Piandelmedico 74, 60035 Jesi (Ancona), Italy
Authors to whom correspondence should be addressed.
Received: 9 January 2020 / Revised: 27 January 2020 / Accepted: 1 February 2020 / Published: 5 February 2020
Bovine milk contains several β-casein variants, with the A1 and A2 variants occurring most frequently. The presence of some variants, such as A1, B, and C, is considered a risk factor for disease in humans who consume milk. These variants are probably involved in intolerance to milk and some human diseases due to the production of a bioactive peptide with opioid activity during digestion, β-casomorphin 7 (BCM-7). In contrast, the A2 variant is not involved in pathogenetic mechanisms; thus, its presence in milk is a desirable feature. The difference between the A1 and A2 variants is a mutation at position 67 of the β-casein gene (CSN2), which causes an amino acid to change from histidine (in the A1, B, and C variants) to proline (in the A2 variant). To select dairy cows on the basis of the presence of the β-casein variant A2, allele frequencies of CSN2 variants were evaluated in Italian dairy cows reared in central Italy. The results of this study may help with the selection of animals with the β-casein gene variant A2 to produce a more digestible milk that only contains the β-casein variant A2.