ARYLESTERASE POLYMORPHISM IN 2 TYPES OF PRAMENKA SHEEP

The variability of arylesterase (EsA) in the plasma of sheep is an example of the physiological implication of enzyme polymorphism. It was clinically observed that administration of the antiparasitic medicine Haloxane, besides antiparasitic effects, can sometimes induce neurotoxic symptoms and death of the sheep. A reduced activity of arylesterase was determined in all Haloxane succeptioble individuals. In this paper, the activity of arylesterase is presented for two types of Pramenka sheep. The quick tuba-test identified two phenotypes of the enzyme EsA+ and EsA- (Tucker, 1967). The characteristic frequencies of EsA+ and EsA- genes were 0.021 and 0.79, for Zetska zuja and 0.18, 0.82 in the Svrljiska type of Pramenka. The relatively high frequency of the EsA+ gene of Pramenka enables better detoxication of the organophosphorous component than observed in most other tested breeds of sheep. The determined biochemical polymorphism of the arylesterase locus in Pramenka sheep can be applied alone or together with other genetic markers for identification and (parentage control) of individuals.