Variations in Bovine Plasma A-Esterase Activity and the Relationship Between Plasma and Milk A-Esterase Activities

Open Access
Publisher Website
Google Scholar
Abstract
The distribution of plasma A-esterase (an enzyme catalyzing the hydrolysis of phenyl acetate and resistant to organophosphorus compounds) levels for 83 cows selected from one herd was determined. Some of these values were related with corresponding milk A-esterase levels. Considerable inter - and intrabreed variation in plasma levels of this enzyme were observed. Holsteins, as a group, tended to have higher plasma activi-ties than Jerseys and Guernseys. The average standard deviation in plasma A-esterase levels within individual cows during a 4-month period was 12 enzyme units. Plasma and milk A-esterase levels were related (r = 0.56 for 61 cows for 3 breeds). The average plasma to milk ratio was 1,800:1.