Measuring behavior patterns and evaluating time-sampling methodology to characterize brush use in weaned beef cattle.

With growing interest in provision of brushes for cattle and the implications of brush use for behavioral development and welfare, there is a need to validate methodology for quantifying grooming behavior. Our objectives were to characterize patterns of brush use, including bouts, diurnal activity, and individual variability over 24-h periods, and to validate time-sampling methodologies to characterize these traits, including instantaneous recording at various time intervals and continuous recording for subsets of the day. Data sets from previous experiments involving steers (experiment 1; n = 18) and heifers (experiment 2; n = 64), consisting of start and end times of brush use continuously recorded from video, were used to analyze brush use. We extrapolated data sets representative of a range of instantaneous recording intervals and compared daily brush duration and bout characteristics with corresponding values from continuous recording using linear regression. To assess validity of sampling subsets of the day, we selected 2-h time periods representative of different functional parts of the day and compared hourly brush rates with continuous data using Spearman's rank order correlation (rs). Brush use was variable among individuals. All steers used the brush in experiment 1, but 17% (n = 11 of 64) of heifers in experiment 2 did not. Bout analysis revealed that individuals used the brush for an average of 7 to 8 brush bouts lasting 4 to 6 min, leading to an average of 24 and 36 min/d for experiments 1 and 2, respectively. Cattle used the brush mainly during daylight hours, with peaks around sunrise, sunset, and the afternoon. Instantaneous recording at intervals less than 1 to 3 min, depending on the experiment, provided good estimates of daily brush use duration (R2 > 0.95 and slope and intercept not different from 1 and 0, respectively), but intervals >3 min were less reliable. For bout characteristics, the intercept of the modeled line differed from 0 for most recording intervals for both experiments, and the slope differed from 1 for recording intervals >30 s in experiment 1, suggesting that time sampling may have underestimated true values. Of the 2-h periods compared with 24 h of observation, 1800 to 2000 h was most highly correlated (rs = 0.84) for experiment 1, and 1800 to 2000 h and 1400 to 1600 h were the most highly correlated (rs = 0.71 and 0.74, respectively) for experiment 2 with daily values. When using time-sampling methods to characterize brush use, we suggest that the recording interval used and time of day observed should be carefully considered, as time sampling at an interval of 1 to 3 min may measure daily brush use duration, but continuous recording may be required to capture bout characteristics.

Fever, feeding, and grooming behavior around peak clinical signs in bovine respiratory disease.

Feedlot cattle are monitored for the sickness response, both physiological and behavioral, to detect bovine respiratory disease (BRD), but this method can be inaccurate. Diagnostic accuracy may improve if the BRD sickness response is better understood. We hypothesized that steers around peak BRD would have fever, anorexia, and less grooming than controls. We also expected sickness response magnitude to be greater as clinical and pathological severity increased. Unvaccinated steers were assigned to challenge with 1 of 5 BRD viruses or bacteria (BRD challenge; = 4/pathogen; 20 total), based on susceptibility as determined by serology. Body weight-matched vaccinated animals were given sterile media (Control; = 4/pathogen; 20 total) and housed by treatment (5 pens/treatment). Rectal temperature was logged every 5 min between 0100 and 0700 h, and time spent feeding (24 h/d), in contact with a brush (13 h/d), and self-licking (24 h/d) were collected from video recordings. Steers were examined and a clinical score (CS) was assigned daily. Bovine respiratory disease challenge steers were euthanized after 5 to 15 d (timing was pathogen specific) and the proportion of grossly affected lung (%LUNG) was recorded. The day of highest CS (peak; d 0) for each BRD challenge steer and the 2 preceding days were analyzed for all variables except self-licking (d 0 only); analogous days were included for Controls. Penwise mixed models (pen was the experimental unit) were used to determine which sickness response elements differed between treatments before and at peak disease, and regression using individual-steer data was used to describe relationships between disease severity ( = 35 for CS and = 20 for %LUNG) and fever, anorexia, and grooming. Bovine respiratory disease challenge steers had fever (1.1°C higher; < 0.01) and anorexia (35% lower feeding time; = 0.03) but did not differ from healthy Controls for brush contact ( = 0.37) or self-licking ( = 0.15). Higher CS and more %LUNG were associated with increased fever (d 0; ≤ 0.04) and lower feeding (d 0; < 0.01), brush contact (d 0; ≤ 0.03), and self-licking ( ≤ 0.05) duration relative to lower CS and less %LUNG. In conclusion, fever and feeding time are good BRD diagnostic measures around peak CS. Further study is needed to clarify why grooming was not a good measure. The sickness response is greater as BRD severity increases; fever is most closely related to CS and anorexia is most closely related to %LUNG. Regardless of which aspect is monitored, cattle with milder disease may be more difficult to detect than sicker animals.