Two cohorts of Bos indicus crossbreds were studied to determine the relationships between temperament and growth in a feedlot and commercial carcass characteristics. Prior to entry to the feedlot, one cohort received intensive, short-term training at weaning but minimal handling before and after weaning, while the second cohort received similar training at weaning and also experienced a 4-month period of relatively intense handling immediately before entering the feedlot. Both cohorts entered the feedlot at similar ages. Temperament was recorded as the animal's flight speed, which is the time taken for the animal to cover 1.7 m after leaving a weighing crush, with fast times indicating animals that have poor temperaments. Average flight speed scores of animals in the 2 cohorts differed substantially, with 51 and 12% of animals in cohorts 1 and 2 respectively having fast flight speed scores. Conversely, 23 and 69% of animals in cohorts 1 and 2 respectively had slow flight speed scores and could therefore be regarded as docile. In the first cohort, animals with slow flight speeds gained weight more rapidly (P<0.05) to achieve heavier slaughter and carcass weights (P<0.05) than animals with fast flight speeds. The relationship between flight speed and growth in the feedlot in the second cohort was not significant, although animals with the fastest flight speeds in that cohort had the lowest liveweight gains. Docile animals in both cohorts had comparable liveweight gains in the feedlot. These results suggest that animals with slow flight speed scores (good temperaments) may grow faster in a feedlot than animals with faster flight speed scores (poorer temperaments), regardless of whether the favourable scores result from intensive, long-term handling or because the animals are naturally docile. There was no relationship in either experiment between flight speed and fat thickness or carcass bruising, when bruising was scored simply as presence or absence of bruising. A negative relationship was evident between flight speed score and dressing percentage in the second cohort (P<0.05). The relationship between flight speed and dressing percentage was not significant in the first cohort. It is suggested that feedlot operators could select potential feedlot animals on the basis of temperament before entry to the feedlot to improve performance in the feedlot.
