[Biochemical changes in the blood of pigs after exertion]

15-minute forced movement of pigs evoked after 18 to 24 hours an increase in the activity of creatine kinase, lactate dehydrogenase and aspartate aminotransferase and in the level of non-esterified fatty acids in blood serum. The changes in the enzyme activity following muscular strain were individual. The pig group with higher average weight gains, fed the diet containing 284 g of crude protein per 1 kg, showed greater differences in the muscular enzymatic activity than the animals with lower weight gains, fed the diet containing 260 g crude protein per 1 kg. Single administration of vitamin E (six hours before strain) did not subdue the elution of enzymes from tissues after muscular strain. Another important strain factor was the fixation of pigs by trying them outside their own group.