Relationships of a novel objective chute score and exit velocity with growth performance of receiving cattle.

Animals with excitable temperaments often have decreased gains that have been associated with decreased intake and efficiency. Different temperament measures probably measure different specific underlying traits. Commonly used temperament measures include both objective and subjective measures. Subjective measures present potential difficulties for making across-study comparisons and thus for generalizing quantitative relationships. One objective of this experiment was to evaluate 2 related, but different, measures associated with temperament, where 1 measure is a new, objective measurement based on the common subjective chute score measures. Also, there is reason to believe that RDP requirements of animals may vary with temperament. To examine the relationships between temperament measures and nutrient use, 192 crossbred steers were used in a 58-d randomized complete block design experiment. Temperament treatments (assigned prior to d 1) were chute exit velocity (EV; slow vs. fast) and objective chute score (WSD; low vs. high), a novel temperament measure that was the SD of weights collected at 5 Hz for 10 s while an animal was restrained in a chute with its head caught. Both were measured on d -8, 1, 2, 16, 30, 56, and 58, where d 1 was the day that animals were allotted to treatment groups and began receiving experimental diets. Steers were fed a diet with 1 of 3 RDP levels (75%, 105%, and 120% of RDP requirements). There were no main effects or interactions with RDP ( ≥ 0.12); thus, it was removed from the statistical model for subsequent analyses. There were no interactions between EV and WSD ( ≥ 0.11). Slow EV animals had greater ADG ( = 0.02) and DMI ( ≤ 0.09) than fast EV animals, but there was no effect of EV on G:F ( > 0.14). For d 0 to 58, high WSD animals had greater DMI ( ≤ 0.09) than low WSD animals but no difference in ADG ( = 0.23), whereas low WSD animals tended to have increased G:F ( = 0.11). Results of this study give additional confirmation that EV is associated with DMI and growth and provide evidence that a novel measure of behavior, WSD, is also related to growth, independently of EV. Because WSD and EV appear to measure different underlying behavioral traits, use of both measures may improve our ability to discriminate among temperament categories for growing cattle.