ABSTRACT
Identification of cattle by ear tagging is legally required to ensure traceability. However, studies indicate that ear tagging causes pain-associated physiological and behavioural responses. The wound healing process and prevalence of wound lesions in calves remain mostly unknown. Therefore, this study sought to estimate the prevalence of wound lesions and identify associated risk factors by assessing ear tagging management in unweaned dairy calves. We conducted one field study with single visits to estimate the prevalence of wound lesions and associated risk factors (Study 1, 42 farms, 802 calves) and one follow-up study with repeated visits to assess farmers' view on ear tag management, the relationship between calf health and wound healing, and the development of wound lesions over time (Study 2, five farms, 42 calves). Study 1 comprised a short interview with the farmer (four questions regarding ear tagging). Ear tag position (on or between ridges) and wound lesions were evaluated using a three-level scoring system (1 = no blood, scab, or pus discharge; 2 = incrustation or scab and slight blood or pus discharge; and 3 = heavy purulent discharge, tissue deformation, or both). In Study 2, farmers were interviewed about ear tagging (30 questions), and 10 calves from each farm were assessed on the day of ear tagging and 1, 3, and 6 weeks after tag insertion. Calf health, ear tag position, and wound characteristics were assessed during all visits. Both studies were analysed descriptively, and odds ratios (ORs) for wound lesions in Study 1 were calculated using logistic regression. Of the ears assessed in Study 1, 31.1% showed clinical signs classified as category 2. Score 3 was less common and was found for 6.7% of all ears. Although the highest incidence of wound lesions was found in calves aged 2-4 weeks, wound lesions were also found in calves aged >10 weeks (18.5%). Identified risk factors for wound lesions were small farm size, calf age, single housing, group size, placement of ear tags on ridges, and other ear's score. Individual farmers in Study 2 were able to place ear tags very accurately, although awareness about ear tag lesions appeared to be low among farmers. Sensitising farmers to this issue, implementing routine check-ups of ear tag wounds 2 weeks after insertion, and considering the identified risk factors may reduce animal welfare impairments associated with ear tagging.
