EFFECTS OF AGE BODY WEIGHT STAGE OF GESTATION AND SEX ON PLASMA GLUTAMIC-OXALOACETIC AND GLUTAMIC-PYRUVIC TRANSAMINASE ACTIVITIES IN IMMATURE HOLSTEIN CATTLE

Glutamic-oxaloacetic and glutamic-pyruvic transaminases were measured in the peripheral plasma of 367 Holsteins in three herds, including open and bred heifers and young bulls. All animals were sampled within a three-week period when the daily mean temperature varied only 13 degrees Fahrenheit, making possible a within-season analysis. Since there was a highly significant difference (P < 0.01) among open heifers between herds for glutamic-pyruvic transaminase, all data were analyzed within individual herds. In Herd 2, age affected the glutamic-oxaloacetic (P < 0.05) and glutamic-pyruvic (P < 0.01) activity of open heifers, while in Herd 1 age affected only glutamic-oxaloacetic activity (P < 0.05). When the age groups were partitioned into individual degrees of freedom, there were also quadratic and cubic relationships (P < 0.01) of age with both transaminases in Herd 2. In Herd 3 there was a linear relationship between body weight and glutamic-pyruvic transaminase for open heifers (P < 0.05). Age affected both enzymes in young bulls (P < 0.01), and a quadratic effect of age on glutamic-oxaloacetic, and quadratic, quartic, and quintic effects of age on glutamic-pyruvic transaminase were observed. No significant differences were observed between open heifers and young bulls, the means being 41.71 and 22.53 units, respectively, for glutamic-oxaloacetic and glutamic-pyruvic transaminases for open heifers, while the means were 42.72 and 23.59, respectively, for glutamic-oxaloacetic and glutamic-pyruvic transaminase for young bulls. Lowered enzyme activity in bred heifers was associated with advancing stages of pregnancy, but no relation to age or body weight was observed. Growth rate, age of puberty, and physiological as well as chronological age, and other components of management and environment cause differences in plasma of both transaminases. © 1969, American Dairy Science Association. All rights reserved.