Abstract Individual temperament can influence the success of estrus synchronization (ES) protocols. A recent study at Kansas State University found that acclimating commercial beef heifers to the working facility and human interaction prior to the handling events of an ES protocol resulted in potential improvements in heifer temperament and increased pregnancy rates (Tastad, 2025). This suggests that interventions aimed at reducing stress and improving welfare during handling could mitigate adverse impacts on reproductive outcomes, and that strategies providing positive reinforcement during handling may offer an additional approach to improving reproductive success. Therefore, the objective of this study was to explore the effects of using a cattle brush device as positive reinforcement during the handling events of the ES protocol on temperament and pregnancy rates of beef cows and heifers to fixed-timed artificial insemination. The hypothesis was that beef females exposed to the cattle brush during the handling events of the ES will have improved temperament by completion of the estrus synchronization protocol and improved conception rates to TAI. A total of 71 heifers and 162 cows were stratified by reproductive tract score and temperament, and then randomly assigned to either the treatment (TRT) or control (CTRL) groups. All females were enrolled in the 7-d-CO-Synch + CIDR protocol and received timed-artificial insemination (TAI) on day 10. All females were inseminated utilizing a breeding box. On days 0, 7, and 10 of the ES protocol, TRT animals encountered a spring-mounted brush in the alleyway prior to chute entry, while the brush was removed for CTRL animals. Chute score (CS) and exit velocity (EV) were recorded on days –10, 0, 7, and 10, and a box score was recorded on day 10. Estrotect breeding indicators were applied on day 7 and evaluated on day 10 to measure estrus response. Pregnancy was diagnosed via transrectal ultrasonography 33 days post-TAI for heifers and 68 days for cows. No treatment differences in CS were observed on days–10, 0, or 7 (P 0.10). However, on the day of TAI, TRT heifers had significantly lower CS (P 0.01) and box scores (P 0.01) than CTRL heifers, while TRT cows tended to have lower CS values (P 0.10). Exit velocity did not differ between groups, but both cows and heifers showed a day effect (P 0.01). Estrotect scores were unaffected by treatment (P 0.10). Pregnancy rates were similar between TRT and CTRL groups for both heifers and cows (P 0.10). However, estrus expression had a positive influence on pregnancy outcomes in both heifers (P 0.01) and cows (P 0.05). Days postpartum also tended to affect cow pregnancy rates (P 0.10). Additional research is needed to determine the effects of positive reinforcement with a brush in the chute alley on reproductive production measures.
Stock et al. (2026) studied this question.