Interactions between the beta-adrenergic agonist salbutamol and genotype on meat quality in pigs

Salbutamol (2.7 ppm) fed to pigs between weaning and slaughter increased ADG (5%), dressing percentage (2%) and cross-sectional area of the longissimus (LD) muscle (14%). In fatter, White-line-sired pigs, but not in leaner, Meat-line-sired animals, it reduced backfat thickness (25%). Liver weight and glycogen concentration also were decreased. In neither genotype were there effects of Salbutamol on pH45, drip loss or reflectance value of the LD, but ultimate pH was elevated in semimembranosus (SM), adductor (AD) and supraspinatus (SS) muscles, resulting in reduced color saturation values. Total muscle heme pigment concentrations were reduced by 10 (SS) to 19% (LD and SM) and the intramuscular fat concentration of the AD, but not the LD, was reduced by 21%. Treated pigs had LD and SM muscles that when measured instrumentally were 15 and 8% tougher, respectively, after cooking, but the texture of the SS was not significantly altered by treatment. Salbutamol increased plasma lactate and creatine phosphokinase (CPK) concentrations. Compared with White-line-sired animals, Meat-line-sired pigs had a higher dressing percentage (2%) and LD muscles with larger cross-sectional area (13%). They also had higher circulating CPK levels.