Effects of temperament on growth and reproductive performance in heifers12

The present study evaluated the effect of temperament on heifer BW, postweaning gain, and pregnancy status. Temperament was evaluated on 259 Angus-sired and 173 Brahman-influenced heifers. Temperament was assessed on heifers at weaning (FALL) and when they were yearlings (SPR) by chute score (CS), exit velocity (EV), and a combination of CS and EV (COMB). Chute scores were categorized into low (CS 1 and 2), moderate (CS 3), and high (CS 4 and 5). Based upon the mean and SD of each, EV was categorized into 3 levels of slow, moderate, and fast, and COMB score was categorized into 3 levels of low, moderate, and high. The FALL assessment of EV (slow, moderate, and fast), affected (P < 0.05) initial (238, 234, and 227 kg) and final BW (402, 394, and 382 kg) and postweaning gain (164, 161, and 155 kg). The FALL assessment of COMB (low, moderate, and high), affected (P < 0.05) initial BW (238, 231, and 228 kg), final BW (402, 389, and 384 kg), and postweaning gain (165, 158, and 155 kg). The SPR assessments of temperament, i.e., all methods, were generally effective (P < 0.05) in elucidating differences in BW, but these assessments occurred at an older age in heifers. Measures were generally not effective in identifying differences in pregnancy status. Based upon broad effectiveness to elucidate BW and postweaning gain differences, EV and COMB were the preferred measures for FALL assessment. These measures and their relationships to BW were consistent across Angus-sired and Brahman-derivative heifers.