Plasma malonaldehyde (MDA) and total antioxidant status (TAS) during lactation in dairy cows

Metabolic profiles are widely used to monitor health, reproductive status and nutritional status. In the last few years, the evaluation of oxidative stress has contributed increasingly to our knowledge of the fundamental mechanisms involved in metabolic disorders, especially important in dairy cows, in which lactation imposes great physiological demands on the body's homeostatic mechanisms. The aim of the present study was to evaluate oxidative status in healthy cows during lactation (from lactation onset to peak lactation) using two parameters: (i) plasma levels of malondialdehyde (MDA) and (ii) total antioxidant status (TAS). Our results confirm that nutrition can influence the characteristic metabolic changes occurring between lactation onset and peak lactation. In addition, the combination of MDA and TAS can provide complementary information about the metabolic status of the cow. Thus, the proper metabolic adaptation to the onset of lactation, showed by metabolic profiles, contrasts with the high levels of free radicals which cause lipid peroxidation and high MDA values (68.99+/-33.64 microm/L) which is maintained only for a short period of time. In this moment, the antioxidant system can cope efficiently with lipoperoxide production. The most remarkable fact was the great inter-individual variations observed in MDA that might be studied in further investigations. When the animal reaches peak lactation, metabolic status is stabilized, and this is reflected by antioxidant status with mean values of 28.87+/-5.33 microm/L for MDA and 0.154+/-0.002 mmol/L for TAS values.