[Reaction of muscles to a stimulating environment--effects on the loin muscle (M. longissimus) of Landrace pigs].

The effects of an enriched environment on growth, meat quality, and muscle biological traits were investigated using 64 castrated pigs (age range 7 to 20 weeks). Positive emotional appraisal was induced by a system that acoustically frequently called individuals out of a group (n=32) to a feeding station, where they were rewarded with small portions of feed. The results were compared with traditional fed pigs (Control; n = 32). There was no environmental effect on live weight and lean muscle percentage. However, the stimulating keeping regime reduced the intramuscular fat content of the M. longissimus by 0.2 % and increased the protein content by 0.5 %. Moreover, the drip loss of M. longissimus was 1.1 % lower in the treatment group. The analysis of muscle fibre traits (biopsy samples of M. longissimus) showed a 7 % higher proportion of oxidative muscle fibres in the pigs reared in the enriched environment. This fibre type showed a tendency to increased fibre areas. These findings indicate a higher oxidative capacity of the muscle. However, the activity of the inarker enzyme citrate synthase (CS) was not influenced and the activity of lactate dehydrogenase (LDH) was even increased compared to the control animals.