Establishing optimal lairage time for slaughter horses: welfare and meat quality aspects

This study assessed the impact of lairage duration (0, 3, 7, and 24 h) and sex (mares vs. geldings) on haematological welfare indicators, carcass bruising, and carcass and meat quality traits in slaughtered horses. Data were obtained from eight deliveries of in total 133 horses from a single assembly point. Slaughter without lairage (0 h), especially in geldings, resulted in higher (P < 0.05) blood lactate and glucose levels and a higher (P < 0.05) incidence of linear bruises, mainly in the loin region, indicating handling-related stress during unloading and movement to stunning. In contrast, overnight lairage (∼24 h), especially of geldings, resulted in reduced glucose, lactate and reduced glutathione levels (P < 0.05), and elevated (P < 0.05) ceruloplasmin and advanced oxidation protein products concentrations. This was accompanied by a higher (P < 0.05) frequency of moderate and circular bruises, suggesting increased agonistic interactions between horses during prolonged lairage. Horses held for 3-7 h lairage, showed intermediate lactate and glucose values (P < 0.05), the highest reduced glutathione activity (P < 0.05), and the greatest proportion of non-bruised carcasses (P < 0.05). Lairage duration did not affect (P ˃ 0.05) carcass quality traits, except for live weight loss, which was highest after overnight lairage (∼24 h), particularly in geldings (P < 0.05). Meat from horses slaughtered without lairage (0 h), especially geldings, had lower both initial and ultimate pH (P < 0.05), higher initial temperature (P < 0.05), higher drip and cooking losses (P < 0.05), paler colour (P < 0.05), and the highest proportion of acid meat with ultimate pH < 5.4 (P < 0.05). However, overnight lairage (∼24 h), particularly in geldings, resulted in higher meat pH (P < 0.05), lower drip and cooking losses (P < 0.05), darker colour (P < 0.05) and the highest proportion of DFD-like meat with pH ≥ 6.0 (P < 0.05). Horses, irrespective of sex, subjected to 3-7 h lairage produced meat with normal pH (5.4-5.9), intermediate colour and water-holding capacity traits, and the lowest percentage of meat quality defects (P < 0.05). In conclusion, a moderate lairage period (3-7 h) optimises both horse welfare and horsemeat quality.