An association between the level of oxidative stress and the concentrations of <scp>NEFA</scp> and <scp>BHBA</scp> in the plasma of ketotic dairy cows

<jats:title>Summary</jats:title><jats:p>The aim of this study was to evaluate the oxidative status in ketotic cows. We observed changes in the oxidative status and correlations between the oxidative and metabolic status in non‐ketotic (<jats:italic>n</jats:italic> = 10), subclinical ketotic (<jats:italic>n</jats:italic> = 10) and ketotic cows (<jats:italic>n</jats:italic> = 10). Plasma samples were analysed by standard biochemical techniques and <jats:styled-content style="fixed-case">ELISA</jats:styled-content> to determine traditional metabolic parameters: triglyceride (<jats:styled-content style="fixed-case">TG</jats:styled-content>), phosphonium (P), calcium (Ca), aspartate aminotransferase (<jats:styled-content style="fixed-case">AST</jats:styled-content>), alanine aminotransferase (<jats:styled-content style="fixed-case">ALT</jats:styled-content>), alkaline phosphatase (<jats:styled-content style="fixed-case">ALP</jats:styled-content>), total protein (<jats:styled-content style="fixed-case">TP</jats:styled-content>), albumin (<jats:styled-content style="fixed-case">ALB</jats:styled-content>), immune globulin (Ig), total cholesterol (<jats:styled-content style="fixed-case">TC</jats:styled-content>), high‐density lipoprotein (<jats:styled-content style="fixed-case">HDL</jats:styled-content>), very low‐density lipoprotein (<jats:styled-content style="fixed-case">VLDL</jats:styled-content>) and lactate dehydrogenase (<jats:styled-content style="fixed-case">LDH</jats:styled-content>); energy metabolism indices: glucose, <jats:italic>β</jats:italic>‐hydroxybutyrate (<jats:styled-content style="fixed-case">BHBA</jats:styled-content>) and non‐esterified fatty acids (<jats:styled-content style="fixed-case">NEFA</jats:styled-content>); and indices of oxidative status: malondialdehyde (<jats:styled-content style="fixed-case">MDA</jats:styled-content>), hydrogen peroxide (H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>), vitamin C, vitamin E, superoxide dismutase (<jats:styled-content style="fixed-case">SOD</jats:styled-content>), glutathione peroxidase (<jats:styled-content style="fixed-case">GSH</jats:styled-content>‐Px), catalase (<jats:styled-content style="fixed-case">CAT</jats:styled-content>), xanthine oxidase (<jats:styled-content style="fixed-case">XOD</jats:styled-content>) and total antioxidant capacity (<jats:styled-content style="fixed-case">TAOC</jats:styled-content>). The results of this study showed that plasma glucose levels were lower in ketotic and subclinical ketotic cows than in non‐ketotic cows; however, the plasma <jats:styled-content style="fixed-case">NEFA</jats:styled-content> and <jats:styled-content style="fixed-case">BHBA</jats:styled-content> concentrations were higher. In addition, significant decreases in <jats:styled-content style="fixed-case">TC</jats:styled-content>,<jats:styled-content style="fixed-case"> HDL</jats:styled-content> and <jats:styled-content style="fixed-case">VLDL</jats:styled-content> and significant increases in <jats:styled-content style="fixed-case">AST</jats:styled-content>,<jats:styled-content style="fixed-case"> ALT</jats:styled-content> and <jats:styled-content style="fixed-case">LDH</jats:styled-content> were observed in the plasma of the ketotic cows. The ketotic cows showed decreased plasma <jats:styled-content style="fixed-case">SOD</jats:styled-content>,<jats:styled-content style="fixed-case"> CAT</jats:styled-content>, vitamin C and vitamin E, inhibited hydroxyl radical capacity and increased plasma H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> and <jats:styled-content style="fixed-case">MDA</jats:styled-content>. There were positive correlations between the plasma <jats:styled-content style="fixed-case">NEFA</jats:styled-content> and <jats:styled-content style="fixed-case">ALT</jats:styled-content>,<jats:styled-content style="fixed-case"> AST</jats:styled-content>,<jats:styled-content style="fixed-case"> LDH</jats:styled-content> and <jats:styled-content style="fixed-case">MDA</jats:styled-content> and negative correlations between the plasma <jats:styled-content style="fixed-case">NEFA</jats:styled-content> and <jats:styled-content style="fixed-case">TC</jats:styled-content>,<jats:styled-content style="fixed-case"> HDL</jats:styled-content>,<jats:styled-content style="fixed-case"> VLDL</jats:styled-content>,<jats:styled-content style="fixed-case"> SOD</jats:styled-content>, vitamin C, vitamin E, 1542280 uric acid and inhibited hydroxyl radical capacity. In addition, there were positive correlations between <jats:styled-content style="fixed-case">BHBA</jats:styled-content> concentrations and <jats:styled-content style="fixed-case">ALT</jats:styled-content>,<jats:styled-content style="fixed-case"> AST</jats:styled-content> and <jats:styled-content style="fixed-case">LDH</jats:styled-content> and negative correlations between plasma <jats:styled-content style="fixed-case">BHBA</jats:styled-content> concentrations and <jats:styled-content style="fixed-case">TC</jats:styled-content>,<jats:styled-content style="fixed-case"> HDL</jats:styled-content>,<jats:styled-content style="fixed-case"> VLDL</jats:styled-content>, vitamin E and inhibited hydroxyl radical capacity. Overall, ketotic dairy cows experience oxidative stress, which is presumably associated with hyperketonemia and higher <jats:styled-content style="fixed-case">NEFA</jats:styled-content>.</jats:p>