COMPARATIVE GROWTH RATES OF SHORTHORN AND CROSSBRED BEEF CALVES FROM BIRTH TO 1 YEAR OF AGE

Abstract

During the 3 years 1959, 1960, and 1961 the purebred Shorthorn herds at the Experimental Farms at Ottawa, Lennoxville, and Kapuskasing were randomly bred to Shorthorn, Angus, Hereford, and Charolais bulls. Three bulls per breed were used each year. Birth weights and rate of gain from birth to 1 year of age were measured in the 254 calves produced. Breed of sire, sex, year of birth, and age of dam were found to be significant sources of variation contributing to weight at birth, but only breed of sire was a significant source of variation in the rate of gain from birth to 1 year of age. Charolais-sired calves were heaviest at all ages, and Hereford next heaviest at all ages. Angus-sired calves were lightest at birth two years of three, but at weaning they were heavier than the purebred Shorthorn calves. The purebred Shorthorns were lightest at weaning and at 1 year of age.