SERUM PYRUVATE-KINASE AND ITS RELATION TO STRESS SUSCEPTIBILITY IN PIGS

Four blood tests, complementary to the halothane test, have been scree ned for their capacity to discriminate between homozygous and heterozy gous stress resistant and stress susceptible pigs : TBARS in plasma, l ipid peroxides from erythrocytes and plasma creatine and pyruvate kina se activity. Blood samples were collected from homozygous (NN) and het erozygous (Nn) stress resistant and homozygous stress susceptible (nn) pigs, while subjected to the halothane test. Serum creatine kinase an d pyruvate kinase tests were retained for a more elaborated study. Pyr uvate kinase appears to be a more reliable indicator of stress suscept ibility than the well-known creatine kinase. However both parameters d isplay a considerable standard deviation. Consecutive assays show the pyruvate kinase activity to be dependent on age (weight), which accoun ts for part of the variation; other sources of variation are the condi tions of the exeriment and the way the imposed stress is perceived by the animal. During this experiment a rapid and accurate DNA-test for H AL-genotype detection has been developed (FUJII et al. 1991; COPPIETER s et al. 1992). In spite of this, the pyruvate kinase parameter is a m uch more discriminating and remarkable indicator for stress susceptibi lity than the, in previous years, widely used creatine kinase test.