“…Considering that addressing heterogeneity depends on the nature of variables used to aggregate farms [55] and the process of variable selection [30,48], we adopted a four-step procedure to classify and characterize farms. First, a set of variables were derived from the literature on farm typology, including farm size, number of dairy cows, number of lactating cows, milk yield, labor intensity, stocking rate, amount of concentrates used, feeding/grazing systems used, herd size, farmer's experience, age at first mating, farmers' age, farm facilities and equipment, farm income, household size, hired labor, keeping animal records, milking frequency, farmer education level, use of artificial insemination, lactation period, and calving interval [37,42,49,50,[56][57][58][59][60][61][62][63].…”