In order to study the influence of the economic factor on the objectives used to select the animals, production data of a payment program by milk quality implanted by a milk industry of Rio Grande do Sul were used. The criteria of quality of the referred program consisted of minimum contents of 3.1% of fat, 2.85% of protein and a maximum 500,000 units of somatic cells. The data were stratified in three levels, in agreement with the volume of milk received monthly by the industry from the properties, due to significant differences in relation to the production costs by liters of milk, resulting from the production capacity of the properties. Level 1 included the production of the properties that delivered up to 1,500 liters of milk for month, Level 2, the production between 1,501 and 3,000 liters and Level 3, the ones that delivered above 3,000 liters. The revenues of the components by liter of milk varied due to the allowance received for the volume of milk delivered, obtaining higher values for larger volume. The expenses led to the economic value (R$) for the milk components where production costs in different levels generate different functions of the income. The economic values for the components were of -0.4290; -0.1906 and -0.3772 for fat, -0.0624; 0.0836 and -0.0193 for protein, at levels 1, 2 and 3 respectively; the carrier always presented positive economic value. Also, these values where higher than the other components, showing values 0.1964; 0.2093 and 0.2210 at Levels 1, 2 and 3 respectively.
production cost; profit function; selection objective; milk quality
