Potential predisposing factors for ecchymosis in the intercostal muscles of sheep carcases in South Australia

Context Ecchymosis is an undesirable appearance in meat caused by small bleeds from capillaries broken during the slaughter process. These lesions are heavily trimmed during processing, incurring labour costs and yield losses. Aims To estimate the prevalence of ecchymosis in a South Australian abattoir and investigate potential predisposing factors. Methods A generalised linear mixed model estimated the effects of breed, age, slaughter shift (morning or afternoon), kill date, direct or market consignment, hot standard carcase weight (HSCW, kg), deviation from lot average carcase weight (ZHSCW, standard units), palpated fat score (mm) and time in lairage (h) on the prevalence of ecchymosis. Over 7 days, 12286 lamb and 3802 mutton carcases from 82 properties were scored (0, 1) for ecchymosis. Key results Lambs had a higher prevalence of ecchymosis (14%) than did mutton (1%; P < 0.001), with significant variation between lines of lambs (P < 0.001). Considering lambs only, kill date (P < 0.01), time in lairage (P < 0.001), and the quadratic terms of HSCW (P < 0.001) and ZHSCW (P < 0.01) affected the prevalence of ecchymosis. Conclusions Ecchymosis had a significant prevalence in lambs only. The time lambs spend in lairage and their bodyweight may be predisposing factors for ecchymosis before slaughter and warrant further investigation. Implications The interaction of size and weight extremeness appeared to predispose lambs to developing ecchymosis at slaughter. Farm of origin was another identified risk factor (management group). Whether it was size and extremeness influencing body composition or other mechanisms involved in vascular integrity, is not known. Further research is required to identify these mechanisms so as to establish breeding and management guidelines that will decrease the likelihood and cost of ecchymosis in lambs. Ecchymosis remains poorly understood, but fractured capillaries indicate a weakness in vascular tissue. Given the present study included over 12000 observations in 7 days, ecchymosis in lambs could be used as a model to study vascular weakness in humans.