RESUMEN
Background: Negative energy balance in cows will induce catabolism especially of lipids and the resulting rapid increase of free fatty acids (NEFA) in the blood stream increases the production of reactive oxygen metabolites (ROMs) and promote oxidative stress. Once the animal body is in an oxidative stress state, many molecules in the body may be peroxidized, accelerating the destruction of cells and causing damage to tissues or organs. This study conducted risk assessment of the oxidative stress caused by negative postpartum energy balance in cows by exploring the relationship between negative energy balance and oxidative stress. Materials, Methods & Results: This experiment randomly selected 120 cows at 14 to 21 days postpartum, from an intensive cattle farm in Heilongjiang province, China. Using a negative energy balance standard of β-hydroxybutyric acid (BHBA) greater than 1.2 mmol/L, nonesterified fatty acid (NEFA) greater than 0.4 mmol/L and glucose (GLU) less than three mmol/L, the cattle were divided into a healthy group of 74 cows and a diseased group of 46 cows. The oxidative stress indices of the experimental cows were measured and analyzed using the independent sample t test. Spearman correlation analysis and regression analysis were performed and by using the binary Logistic regression analysis to predict disease, the receiver-operating characteristic curve (ROC) analysis established diagnosis effect and boundary values. Compared with the healthy group, the levels of glutathione peroxidase (GSH-Px), catalase (CAT), vitamin E (VE), selenium (Se) and total nitric oxide synthetase (T-NOS) in the blood of dairy cows in the diseased group were significantly reduced and the level of malondialdehyde (MDA) was significantly increased. The study concluded that negative energy balance is associated with oxidative stress in cows and the blood levels of GSH-Px, CAT and Se can be used...