EFFECTS OF INTERACTIONS BETWEEN TYPE AND MILK-PRODUCTION ON SURVIVAL TRAITS OF CANADIAN HOLSTEINS

Effects of the interaction between type and production on two measures of functional herd life were examined for Canadian Holsteins. Data we re records of survival through first lactation for 1,153,706 cows and number of lactations initiated (maximum of five lactations) for 705,93 0 cows. Survival data were regressed on ETA for type traits of the sir e of each cow after the cows were assigned to groups with low, medium, or high production. Survival through first lactation was analyzed wit h a threshold model. Factors in the model included herd-year-season; a ge at calving; month of calving; interaction of registry status, chang e in herd size, and season; fat and protein production; and linear reg ressions of sire ETA for type within each production class. Numbers of lactations were analyzed with a linear model that also included month of last calving. Overall conformation and udder traits had the larges t effects on survival through first lactation. Effects on number of la ctations for feet and leg traits were about the same as for udder trai ts. Interactions were significant. Type traits were relatively unimpor tant for herd life of low producing cows. Few differences were observe d in the relationships between herd life and type for medium versus hi gh producing cows, indicating no need to increase the emphasis on type in response to current trends for greater production.