Why Entire Male Pigs Have More Skin Lesions at Slaughter05 April 2015
A new study from Ireland shows that entire males were more aggressive and performed more mounts than female pigs and that, as a result, the boars had more skin lesions. It was found that carcase lesion score is a sensitive indicator of aggressiveness and welfare of pigs.
The production of entire males is likely to increase with the introduction of a voluntary EU level ban on castration coming into effect in 2018. However, Dayane Lemos Teixeira and Laura Ann Boyle from the Pig Development Department of TEAGASC Moorepark in the Republic of Ireland report that the rearing of these animals may pose other challenges regarding welfare and production problems relating particularly to carcase quality.
The aim of their study, published in Livestock Science, was to investigate whether there is a relationship between the aggressive and mounting behaviour performed by pigs in the final weeks prior to slaughter and skin lesion scores recorded on farm and on the carcase.
A total of 70 entire male and 71 female pigs (Large White×Landrace) were housed in five pens of each sex (mean of 14.1±0.74 pigs per pen) in the finisher house.
On days −14 and −1 relative to slaughter (Day 0) pigs were individually weighed and skin lesions were scored according to severity. Posture and all incidences of harmful, aggressive and mounting behaviours were directly recorded in three two-hour periods (8–10 h, 11–13 h and 14–16 h) on days −13, −9, −7 and −2.
At the slaughterhouse, tail lesions, skin lesions and bruises were scored on all carcasees.
Teixeira and Boyle observed that boars performed more aggressive (1.8 versus 1.0 aggression per pig and period; s.e.m. 0.22) and mounting behaviours (0.4 versus 0.005 mounts per pig and day; s.e.m. 0.02) than gilts (P≤0.05).
In general, postures were similar in both sexes (P>0.05).
On Day −1, boars had higher skin lesion scores than gilts (11.2 versus 8.2; s.e.m. 0.95; P≤0.05).
Boars had higher skin lesion scores on the carcasees (1.9 versus 1.3; s.e.m. 0.10; P≤0.05) and more fighting-type bruises (4.5 versus 2.3; s.e.m. 0.35; P≤0.05) than gilts.
There was no association between aggressive behaviour and skin lesions scored on farm on Day −1 (P>0.05) but there were positive correlations between aggressive behaviour and skin lesions scored on the carcase (actor: r=0.383, P≤0.001; recipient: r=0.294, P≤0.001, respectively) and fighting-type bruises (actor: r=0.442, P≤0.001; recipient: r=0.297, P≤0.001, respectively).
Skin lesions scored on the carcase were a more sensitive indicator of aggressiveness and welfare of pigs than those recorded on the live animal.
The results from this study reinforce the importance of on-line monitoring of carcase skin lesions in the routine inspection procedures as a complementary tool to identify critical points along the slaughter chain and as an indicator of animal welfare on farm, concluded the TEAGASC researchers.
Teixeira D.L. and L.A. Boyle. 2014. A comparison of the impact of behaviours performed by entire male and female pigs prior to slaughter on skin lesion scores of the carcase. Livestock Science. 170:142–149.
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