Management and Genetic Influences on Survival in Jerseys

Over 119,000 Jersey cows (daughters of 374 bulls) that first calved in 1979 through 1987 were used to evaluate management and genetic effects on suwival in Jersey cows. Survival traits included survival through first lactation, survival to 20 mo after fist calving, and length of productive life (maximum 60 mo). Higher production in first lactation and lower age at first calving were associated with longer productive lives. Registered daughters had longer productive lives than did grade daughters, and regressions of swival on milk yield were more positive for registered daughters. Heritability estimates of survival traits after adjustment for first lactation milk yield (linear and quadratic) from grade daughters, from registered daughters, and from all daughters were low (mean = .05). Genetic correlations among the survival measures using independent data sets based on odd versus even DHIA herd numbers were .77 or higher. Many of the same genes may control culling for reasons other than yield at various ages. Genetic correlations among the survival measures from grade versus registered daughters were moderate to high (.48 and larger). Response to seledon against culling in Jerseys would be slow. (