Resumo

MARTINS, Gabrimar Araújo et al. Economic objectives for dairy cattle selection in a demonstration farm in the Zona da Mata of Minas Gerais. R. Bras. Zootec. [online]. 2003, vol.32, n.2, pp. 304-314. ISSN 1806-9290.  http://dx.doi.org/10.1590/S1516-35982003000200008.

The economic values of dairy cattle were derived from economics and production data of a demonstration farm, the "Pasture Dairy Production System using Holstein Zebu Cattle" at Embrapa-Dairy Cattle. The economic values were estimated by two methods 1) from the partial derivative of profit with respect to each trait, and 2) from the partial derivative of the income/cost ratio, both evaluated at the mean value of all other traits. With the latter method, the economic values of traits considered, expressed in equivalent kg of milk, were: carrier (milk with zero fat and protein), 0.77 /kg, milk fat, - 5.00 /kg, milk protein, -3.65 /kg, mastitis, -155,34 /case, milk flow, 146.00 /kg/min, number of services per conception, -104.50 /service, age at 330 kg, -1.27 /day, days from 330 kg to first calving, -0.51 /day, herdlife, 49.63 /year and dry cow weight, -4.34 /kg. Similar values were obtained with method 1. These results confirm previous literature reports indicating negative economic values for milk fat and protein when these components are not paid for, higher economic value of reducing cow liveweight relative to increasing milk yield and showing great importance for mastitis, milk flow and herdlife and low relative importance of interval from 330 kg to first calving.

Palavras-chave : dairy cattle; economic value; profit function; selection.