The objective of this study was to compute economic values of traits for dairy cattle improvement using an empirical approach. Field recorded data were obtained from the Programme d'Analyse des Troupeaux Laitiers du Quebec (PATLQ) and genetic evaluation data were obtained from the Canadian Dairy Network (CDN). After the editing procedure, the data set consisted of 195,001 lifetime records of Holstein, Ayrshire, Jersey, Brown Swiss and Canadienne cows which calved for the first time between January 1980 and December 1994. / Different profitability measurements were computed and used as the dependent variables in covariance model to compute different sets of economic values. Since the majority of cows produced 5 lactations or less, results obtained by using lifetime profits and profits until the end of the fifth lactation are similar. A kilogram genetic increase in fat production had higher economic values than the same increase in milk production in all breeds. A unit genetic increase in conformation had the highest positive impact on profit while a same increase in capacity had a negative impact on profit. Results obtained by using lifetime profit adjusted for the opportunity cost of postponed replacement showed that this adjustement reduced the influence of type traits on profit. Finally, profits of first lactations were used to study consequences of changes in pricing systems occurred in Quebec in August 1992. Economic values attached to protein production changed drastically. A kilogram genetic increase in protein production had negative economic values in the 80's and positive economic values after August 1992.

No description available.