Muscle metabolic traits, post mortem-pH-decline and meat quality in pigs subjected to regular physical training and spontaneous activity.

Ninety-six female and male pigs were assigned to one of three treatments, 'confined' (C),'trained'(T) or 'free' (F) allowing for different levels of physical activity during the growth interval from 30 to 100kg. Treatment C consisted of individual housing in pens of 2.5 m(2); treatment T of individual housing and regular treadmill training and treatment F of housing in pens of 36 m(2) (40 pigs/pen). In m. biceps femoris (BF), the activity of lactate dehydrogenase (LDH) was decreased between 9 and 12% by training (treatment T vs C). Likewise, in BF from female pigs, training increased the activity of citrate synthase (CS) and of 3-OH-acyl-CoA-dehydrogenase (HAD) by 18 and 21%, respectively. Spontaneous activity (treatment F) reduced the activity of LDH for five muscles between 10 and 16% when compared with treatment C. Around the time of slaughter, glycogenolysis of BF was less for treatment F (6-17%) than for C and T (33-38%). Moreover, in BF from female pigs in treatment F, the initial but not the ultimate pH was increased when compared with treatment C. In comparison to C and T, treatment F improved juiciness in BF from male pigs and increased the amount of salt soluble protein in m. longissimus dorsi.