LIVE BODY MEASUREMENTS IN TEN FIRST CROSSES OF BEEF COWS RAISED IN TWO ENVIRONMENTS

Abstract

Live body measurements on beef cows representing 10 F1 crosses were recorded in 1976 (890 cows) and 1980 (586 cows) at Brandon, Manitoba and Manyberries, Alberta. The crosses included the Hereford × Angus (HA) and crosses sired by Charolais, Limousin, and Simmental bulls out of Angus, Hereford, and Shorthorn dams. Cows were classified into three nursing status groups in 1976, dry-nursing, nursing-dry, and nursing-nursing, only two groups in 1980, dry-nursing and nursing-nursing. The group refers to the status in the year prior to the measurements and the year of measurement, respectively. The objectives of the study were: (1) to compare the HA to the exotic crosses and determine differences among the exotic crosses; (2) to evaluate the effect of nursing status on the live cow measurements; (3) to study the differences between the two locations; and (4) to relate the size of the cows in 1976 relative to their size in 1980. Exotic cross cows were higher at the withers and hips, longer, heavier at weaning, and had less subcutaneous fat cover than HA cows. Differences among the exotic crosses were found for all traits in both years with the exception of subcutaneous fat cover in 1980. Possible genotype × environment interactions were observed as a cow cross × nursing group interaction was found for subcutaneous fat cover at both locations in the 1976 data and a cow cross × location interaction for body length in the 1980 data. Nursing status affected cow weight at weaning, subcutaneous fat cover, height at the withers, and body length in the 1976 data but only cow weight at weaning and subcutaneous fat cover in the 1980 data set. Differences between locations were found for cow weight at weaning and height at the withers in 1976, and subcutaneous fat cover and body length in 1976 and 1980. Cows at Brandon achieved a greater proportion of their mature body size by 1976 than their contemporaries at Manyberries for all traits measured. Key words: Cattle (beef), breed crosses, cow, body measurements, genotype environment interaction