Effects of the stunning procedure and the halothane genotype on meat quality and incidence of haemorrhages in pigs

A total of 313 pigs (127 halothane-free, NN, and 186 heterozygous halothane , Nn) were slaughtered in four batches at two commercial abattoirs with two different stunning systems, an automatically head-only followed by head-to -chest electrical stunner and a compact carbon dioxide (CO2) stunning unit. Meat quality on the loin muscle was assessed by measuring electrical condu ctivity (PQM) and colour (Minolta CR 200) at 7 h post mortem, and ultimate pH. Loins showing PQM > 6.0 mus were classified as clearly pale, soft and e xudative (PSE) meat. The incidence of petechiae, ecchymosis and haematomas in the shoulders, loins and hams was also evaluated. In the abattoir equipp ed with the electrical stunning system, a higher incidence of potentially P SE meat was found compared with the abattoir equipped with CO2 stunning (35 .6 vs. 4.5%). Likewise, electrical stunning increased significantly the inc idence of petechiac in the loins, shoulders and hams, and ecchymosis in the loins and hams. Also, the incidence of PSE meat was higher in the Nn pigs compared with NN pigs (24.7 vs. 7.9%). It is suggested that for improving m eat quality and reducing incidence of haemorrhages electrical stunning shou ld be avoided. Further improvements in meat quality can be achieved by elim inating the halothane gene specially in CO2-stunned pigs. (C) 2001 Elsevier Science Ltd. All rights reserved.