Abstract

Association of serum paraoxonase (PON) activity and oxidative stress in dairy cows as well as the relation between PON activity and HDL-c concentration were studied. A significantly lower PON and arylesterase (ARE) activities (P˂ 0.05) was found in cows with oxidative stress (parasitic and mastitic animals) compared to clinically healthy cows. Serum glutathione peroxidase (GPX) activity and malondialdehyde (MDA) level were also markedly reduced in cows with oxidative stress where as the serum HDL-c, LDL-c and cholesterol concentration showed significant reduction than the values in healthy cows. The results indicate a higher serum TAG and vLDL-c values in normal cows than in oxidative stress cases. The total protein content, albumin and globulin concentrations were showed slightly lower values in oxidative stress than in normal cows. A decrease serum PON activity may lead to reduction of anti oxidative protection during marked oxidative stress.

Key words: Bovine paraoxonase, Oxidative stress, Glutathione peroxidase, Malondialdehide