The objectives of this study were to determine some biochemical parameters (aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, alkaline phosphatase, total protein, albumin, calcium and inorganic phosphorus) in blood plasma in clinically healthy Holstein and Swiss Brown cows during housing and pasture periods, and to evaluate the effect of breed on these parameters.

The study was performed on 107 cows (65 Holstein and 42 Swiss Brown), 3.5 - 7 years of ages. Blood samples were collected during housing and pasture periods from cows.

The mean plasma values of aspartate aminotransferase (p<0.001), alanine aminotransferase (p<0.01), lactate dehydrogenase (p<0.001) and total protein (p<0.01) at pasture period were higher than those at housing period, but the mean inorganic phosphorus level at pasture period was significantly lower (p<0.05) than the housing period. In addition to, the mean aspartate aminotransferase activity of Swiss Brown cows at pasture period was higher (p<0.01) than the mean aspartate aminotransferase activity of Holstein cows. Except of the aspartate aminotransferase activity found no significant differences depending on the breed on the other parameters in both periods.