Bovine dairy market, after the abolition of milk quotas, is causing dairy sector restructuration. Product differentiation is one of the strategies that are implementing dairy farms, mainly small family farms. In this context, a new type of differentiated cow´s milk has appeared known commercially as A2 milk. This type of milk is devoid of A1 β‑casein protein, which can cause intolerance and gastrointestinal discomfort due to higher β‑casomorphin‑7 release after digestion. In the present work, the possibilities and implications of a selection in favor of A2 β‑casein were analysed in family farms in Guipúzcoa (Spain). The results obtained from 1868 genotyped females showed that the frequency of allele coding the A2 protein was 0.55 and no unfavorable associations were found between A2 allele and the breeding values for production, functional and morphological traits nor other genes or haplotypes. Under this scenario, and using only A2A2 bulls, the use or not of sexed semen, together with different replacement rates that are applied, will determine the period and the economic cost of herd conversion to A2 milk production. In a reasonable cost strategy, the estimated conversion period is between 8 and 15 years, which, in a 150‑cow farm, could imply an approximate cost between 6,000 and 1,000 €/year, respectively.

Alfonso L, Urrutia O, Mendizabal JA (2019). Conversión de las explotaciones de vacuno de leche a la producción de leche A2 ante una posible demanda del mercado: posibilidades e implicaciones. ITEA‑Información Técnica Económica Agraria 115(3): 231‑251. https://doi.org/10.12706/itea.2019.001