PRETEST HERD EFFECTS ON STATION PERFORMANCE TEST

Abstract

Effects of herd of origin and the relationships between pretest and station test environments were examined from pre- and postweaning performance records of 1675 crossbred male and female calves of Hereford, Angus and Shorthorn dams, sired by 20 Charolais, 12 Simmental and 15 Limousin sires. The calves were born during 1969–1972 and raised to weaning in 45 herds from Manitoba, Saskatchewan and Alberta, and were then transported to the Brandon or the Lacombe Research Station for a 140-d postweaning performance test. Fixed effects and variance and covariance components were estimated from a mixed model which included fixed effects of herd-year, sex of calf and breed of sire and random sire effects. Herd-year effects were significant (P < 0.01) for all performance traits studied. Herd-year mean squares expressed as a percentage of the corrected total sum of squares accounted for 25.81% in the pretest period to a maximum of 54.26% in the warm-up period and then decreased to 6.78% in the 140-d period. Herd-year differences were relatively small in the later part of the test. Correlations of herd-year solutions ranged from −0.10 to 0.05 and of environments ranged from −0.09 to 0.02 between pretest average daily gain (ADG) and ADG at various test intervals. The low environmental correlations suggest that the performance of calves centrally tested at the Brandon and Lacombe Research Stations were not affected by the pre-test herd environment. Key words: Beef cattle, station test, pretest herd effects, environmental correlation