Esterases in the milk and blood plasma of swine. 2. Activities at different stages during the lactation and suckling periods, and plasma arylesterase as a gene-controlled enzyme

Abstract

The variation in activity of butyrylcholinesterase of sow''s colostrum and milk, and that of acetylarylesterase and butyryl-cholinesterase of swine blood plasma, have been studied in relation to the stage of lactation. Butyrylcholinesterase activity of colostrum and milk declines during the first weeks after parturition and then rises, being rather constant during the later part of lactation. The electro-phoresis pattern of colostrum is characterized by two peaks of high cholinesterase activity. The faster-moving component, which is identical with the cholinesterase present in blood plasma, disappears during the first days of lactation. Butyrylcholinesterase activity of sow''s blood plasma is constant during the lactation. The activity of the pig-lets is lower at birth than that of their mother and then rises to adult levels during the first 2 weeks. Three types of plasmas, with high, intermediate and low acetylarylesterase content, are found. Newborn piglets have low plasma-arylesterase activity irrespective of high activities in both or one of the parents. At birth, most of the low activity towards phenyl acetate is due to butyrylcholinesterase. The low plasma arylesterase activity is not due to the presence of an inhibitor. Evidence is presented that the power of piglets to synthesize acetylarylesterase is gene-controlled. The increase in plasma ary-esterase of some piglets during the first weeks of life runs parallel with the increase of albumin concentration. The implications of these observations are discussed.