Early variations of blood plasma gamma-glutamyl transferase in newborn calves--a test of colostrum intake.

Fourteen newborn calves had low gamma-glutamyl transferase catalytic activity concentration in blood plasma (10 to 31 U/liter). Colostrum intake induced a dramatic increase of plasma gamma-glutamyl transferase activity, which was maximal on the 1st or 2nd day (370 to 5000 U/liter) after birth; then plasma enzyme activity slowly decreased and was stable about 100 U/liter on the 20th day. In two calves given either boiled or synthetic milk, plasma gamma-glutamyl transferase activity was not higher than 25 U/liter. Gamma-glutamyl transferase activity of blood plasma in newborn calves is an easy and inexpensive test of colostrum intake.