A novel objective chute score interacts with monensin to affect growth of receiving cattle.

Growth in cattle may be related to animal temperament via alterations in intake or feed conversion. However, temperament is ill-defined, and different temperament measures may relate differently to production traits or interact with dietary factors in their effects. To examine relationships between diet, temperament, growth, and health, 160 crossbred steers (262 ± 22 kg) were used in a 56-d RCBD experiment with a 2 × 2 × 2 factorial treatment structure with 5 pens/treatment. Steers were pen fed a corn silage-based diet with or without monensin (41.9 g/t DM), ad libitum. Temperament treatments (assigned on d -7) were exit velocity (EV; slow vs. fast) and objective chute score (OCS; low vs. high), a novel temperament measure, representing the CV of weights collected at 5 measures/s for 10 s while an animal's head was restrained in a chute. Both were measured on d -7, 0, 14, 28, 55, and 56. Subjective chute scores (SCS; visual estimates of animal activity obtained simultaneously with OCS measures) were measured on d -7 and d 56. Jugular blood samples from d 28 were analyzed for antibody response to leptospirosis vaccine and NEFA concentrations. No monensin × OCS × EV interactions were detected ( ≥ 0.11). There was a positive correlation between SCS and OCS ( < 0.01; = 0.57). Changes in OCS and EV across the duration of the study differed among treatments (treatment × day, < 0.10) and indicated that initial measures may be better proxies of growth than average measures. There were no interactions between EV and OCS ( ≥ 0.15) for any response variable and no interactions among treatments ( ≥ 0.31), nor main effects of temperament factors ( ≥ 0.12) for DMI (%BW). Monensin decreased DMI ( < 0.01) similarly across all levels of EV and OCS. Gains and G:F responses to monensin depended on OCS ( < 0.10) but not EV ( ≥ 0.80). Gain was reduced ( < 0.10) by monensin with low, but not high, OCS, and G:F was increased ( < 0.10) by monensin on high, but not low, OCS. Gain during the second 4 wk was lesser ( = 0.04) in fast, compared with slow, EV animals. Results provide novel indications that certain temperament measures can interact with dietary manipulation to influence animal performance.

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.