Observations on the serum phosphatase of cattle and sheep

Abstract

In apparently normal cows and ewes the variations in serum phosphatase, 0.3-114.3 and 3.0-166.1 units per 100 ml. respectively, are so wide as to lead to the conclusion that its detn. can be of little diagnostic significance. Cows of the Dairy Shorthorn breed show a wider range of values and a greater proportion of high values than cows of 4 other dairy breeds and 1 beef breed. No explanation of this breed difference can be offered. Though the serum phosphatase may differ widely from animal to animal the general level of the individual remains sensibly constant over long periods of time. In both cattle and sheep serum phosphatase activity progressively decreases with advancing age until maturity is reached. Thereafter cattle show little alteration but there is some evidence in sheep of a further slight decrease with advancing age. There is some evidence that pregnancy per se is accompanied by a slightly raised serum phosphatase in dairy cows, though the level of phosphatase does not appear to be correlated with the stage of pregnancy. No evidence was found of correlation between milking capacity and serum phosphatase activity in dairy cows. The high phosphatase activity of the sera of some clinically healthy cows does not appear to be due to an enzyme activator in these sera.