Inbreeding of Canadian Holstein Cattle

Inbreeding coefficients of >3 million Holstein cows and bulls were computed for the Canadian population. Relative to the population base in 1950, the inbreeding coefficients ranged from 0 to 37.5%. During the period of study, trends for inbreeding increased, except for 1978 through 1986, when inbreeding fell or reached a plateau. More recently, for birth years 1987 through 1990, inbreeding has steadily increased at an annual rate of .07 and .21% for cows and bulls, respectively. The mean inbreeding of AI bulls approached 3% in 1990, the last year recorded.