Genetic base and inbreeding of Canadienne, Brown Swiss, Holstein and Jersey cattle in Canada

Abstract

SummaryThe narrowing of the genetic base is of major concern to many cattle breeders and this is a consequence of a small effective population size and an increase in the inbreeding coefficient in cattle populations. Studies of pedigrees of cattle populations found in Canada showed that the effective population size and rate of inbreeding over a 12-year period (1983–94) were 123 and 0.412 percent for Canadienne, 975 and 0.054 percent for Brown Swiss, and 2 183 and 0.024 percent for Jersey cattle populations. Over the same period, the year to year trends in inbreeding coefficients based on co-ancestry was 0.11 percent for Canadienne and 0.07 percent for Brown Swiss cattle populations, and 0.37 percent for Holstein bulls used by the artificial insemination industry. Inbreeding was not found to be a major problem in any of the populations examined. However, only 10 bulls of their respective breed sired 61 percent of the Canadienne, 21 percent of the Brown Swiss, and 29 percent of the Jersey cattle populations, and 41 percent of the Holstein bulls in the bull studs. More and more breeders are demanding proven sires to increase milk production from fewer cows resulting in the narrowing of the genetic base of the national cattle populations. Newer technology that provides precise genetic modification could further contribute to the narrowing of the genetic base compromising the ability to sustain current production and respond to changing markets in the long-term.