Genetic and environmental effects on a temperament score in beef cattle

Abstract

Temperament scores were taken on 8-month-old calves from five calf drops (1976-80) and over three sections of a large crossbreeding trial on the North Coast of New South Wales. A 0-5 scale was used, with lower values for quieter cattle. The heritability �s.e. of temperament score of Bos taurus calves (sired by Hereford, Simmental and Friesian bulls) was 0.03�0.28, and for B. indicus-sired calves (Brahman, Braford and Africander bulls) 0.46�0.37, and for all data combined 0.44�0.25. There was a significant difference (P < 0.01) between the mean score of Brahman-sired halfbred calves (1.96) and B. taurus-sired calves (1.05). The difference was halved to 0.45 points for quarterbred Brahman calves versus B. taurus calves, i.e. as expected for an additive trait. There were significant differences in temperament among calves sired by B. indicus bulls, but there were no significant differences amongst the B. taurus sire breeds. The repeatability (mean � s.e.) of operators' score of 701 weaner calves was 0.67�0.08. From temperament scores of 315 cows at weaning in 1981, an operator repeatability of 0.82�0.08 was obtained. Correlations of cow and calf score were not consistent, but averaged 0.18�0.04 from 547 records. The repeatability of scores taken at two separate times on 132 calves, was 0.43�0.09. The group given a medium level of nutrition had significantly higher temperament scores than those given high or low levels. Sex effects were not significant on scores at weaning. A log transformation of the data equalized the variance of scores of different breeds, but did not affect the conclusions.