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Journal of Dairy Science Vol. 53 No. 4 449-452
© 1970 by American Dairy Science Association ®
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Plasma Glutamic-Oxaloacetic and Glutamic-Pyruvic Transaminase Activities in Holstein Cattle. I. Effects of Stage of Lactation, Gestation, and Level of Milk Production1

L. R. Boots2 and T. M. Ludwick

Department of Dairy Science, The Ohio State University, and Ohio Agricultural Research and Development Center, Columbus 43210

ABSTRACT

A total of 748 jugular vein plasma samples was taken from 69 Holstein cows sampled monthly throughout one lactation and the corresponding gestation period. Glutamic-oxaloacetic transaminase activity varied significantly (P < 0.01) between the seven, 60-day stages of lactation and also showed a significant (P < 0.01) linear relationship, with the highest activity in the first stage, and lowest in the dry cows (52.57 and 31.59 Karmen units, respectively). Glutamic-pyruvic transaminase activity also varied significantly (P < 0.01) between the stages of lactation and showed significant linear (P < 0.01), quadratic (P < 0.01), and cubic (P < 0.05) relationships. The variations in enzyme activity among the 11, 30-day stages of gestation were not significant, but a significant (P < 0.05) linear relationship was observed for glutamic-oxaloacetic transaminase. A regression analysis indicated that milk production was linearly, but negatively, related (P < 0.01) to glutamic-oxaloacetic transaminase activity, whereas glutamic-pyruvic transaminase was related in a quadratic manner (P < 0.05).

FOOTNOTES

1 Contribution to NC-2 Regional Dairy Cattle Breeding Project in Cooperation with USDA.

2 Post-Doctoral Fellow, Department of Obstetrics and Gynecology, University Hospital, The Ohio State University, Columbus 43210.






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