Blood activity of superoxide dismutase and glutathione peroxidase in grazing dairy heifers

Resumo

The objective of this study dealt with the evaluation of the metabolic nutritional status of Cu, Zn, Mn, Fe and Se in grazing dairy heifers, through the determination of the activity of SOD and GSH-Px in blood. Blood samples (10 mL) were taken from 105 heifers randomly selected in 15 dairy farms in Caldas, Colombia (5°4' N y 75°3' W). Forage samples were also collected to analyze Cu, Fe, Mn, and Zn. Mean activity of SOD was 1,390±1,299 U g^-1 Hb, and it was related to the content of Cu, Mn, and Fe in the forage. Mean blood activity of GSH-Px was 389±184 U g^-1 Hb. The highest frequency of values under the reference was about 9%; animals located over 2,000 m over sea level were the most affected. SOD is useful to determine the nutritional metabolic status of Cu, Mn and Fe, but the relationship with Zn is not clear yet, and requires further investigations. The blood activity of GSH-Px in grazing animals, was under the reference values, indicating Se deficiencies.