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Prevalence of Loin Bruising and Tail Lesions in Irish Slaughter Pigs
Loin bruising and tail lesions are potential welfare indicators to record during meat inspection. Loin bruising is associated with increased costs because it necessitates trimming and therefore downgrading of the loin. Tail biting is a well-known problem in the pig industry and even mild tail lesions have been associated with pathologies, reduced carcass weight and increased risk of carcass condemnation/trimming. Potential welfare and economic implications of loin bruising and tail lesions make it imperative to get an accurate picture of the scope of the problem.
Visits to two factories in the Republic of Ireland were conducted in summer 2014. Two observers scored each carcass after scalding/dehairing on the slaughterline and recorded sex, herd, loin bruising (0 – 2) and tail lesion scores (0 – 5). Scores were collapsed into two levels for loin bruising (none/mild, severe) and 3 levels for tail lesions (none/mild, moderate, severe). Prevalence and their range were determined on herd level. Effects of factory and sex were analyzed by SAS V9.3 PROC GENMOD.
In total, 13 133 carcasses were inspected. Severe loin bruising was present in 4.0% of the pigs. Herd level prevalence for severe loin bruising ranged from 0 – 6.0% in factory A and 0 – 21.7% in factory B. Pigs had a higher odds of severe loin bruising in factory B (OR=4.5, 95%CI 3.58 – 5.79) than A. Sex had no effect on loin bruising. Moderate and severe tail lesions were present in 27.3% and 1.0% of the pigs, respectively. Herd level prevalence for severe tail lesions ranged from 0 – 7.9% in factory A and 0 – 9.7% in factory B. For moderate tail lesions this was 16.0 – 66.8% and 4.0 – 40.0%, respectively. Pigs in factory B had significantly lower odds for moderate (OR=0.2, 95%CI 0.19 – 0.23) and severe tail lesions (OR=0.6, 95%CI 0.39 – 0.79) than in factory A. Males had a higher odds of moderate (OR=1.4, 95%CI 1.30 – 1.54) and severe tail lesions (OR=4.2, 95%CI 2.68 – 6.54) than females.
Tail lesions are more common and the larger variation between herds suggests that this is a more suitable welfare indicator than loin bruising which might be affected by slaughterhouse processes (e.g. scalding/dehairing). Tail lesions recorded at meat inspection could provide valuable feedback to producers to inform their herd health/welfare plans.
Keywords: Loin bruising, Tail lesions, Pigs