207. Assessing the Validity of an Emerging Facial Grimace Scale in Beef Calves During Standard Processing Procedures.

Abstract Alternative methods of assessing pain are essential for those that do not communicate verbally. Pain can be self-reported, but quantification through observation is essential for non-verbal populations (e.g., infants). Observational scales, such as facial grimace scales, have been adapted and validated for various non-human animals (e.g., mice, pigs), but few studies have applied and validated these scales in cattle. The objective of this research was to explore the efficacy of an emerging facial grimace scale in beef calves implemented during standard processing. Bull and heifer beef calves (n = 14) were separated from their dam and restrained in a squeeze chute where they experienced manual stimulation of the testes (bulls) to simulate a sham castration and/or of the horn base (bulls and heifers) on the poll to simulate a sham dehorning/disbudding. Calves were then allowed 72 h to graze with their dam before undergoing the same procedures described above, excepting with an actual (instead of sham) castration and/or hot iron disbudding. Immediately after and 40 mins following the sham or actual procedure, calves were video recorded for a total of 4 timepoints per calf. Still images were captured from video recordings and trained observers (n = 5) scored six facial action units (FAU) to calculate overall facial grimace scores. Two of five scorers were dropped from the dataset due to their low agreement with other scorers, which resulted in an average interclass correlation of 0.84. Intraclass correlation averaged 0.76 across scorers. Data were analyzed with SAS using a repeated-measures mixed model to test the effect of procedure (sham, actual) and type (castration, disbudding, or castration × disbudding) on facial grimace score, with calf as the subject. Facial grimace score did not differ (P = 0.16) between sham (0.30 ± 0.03) versus actual castration (0.27 ± 0.03); and also did not differ (P = 0.99) between castration (0.29 ± 0.03), disbudding (0.28 ± 0.05), and a combination of the procedures (0.28 ± 0.05). As the facial grimace scale utilized here is emerging, we explored eliminating one FAU from the calculation (i.e., mouth open) as it did not appear in many images. This increased the scores (0.28 for six FAU versus 0.34 for five FAU) but did not affect findings of fixed effects. These data suggest the current facial grimace scale may not accurately reflect pain experienced by beef calves during processing. Because facial grimace scales are intended to increase the accessibility of pain evaluation in standard production settings, more research is needed to refine and validate facial grimace scales in bovine calves before implementation.