The present study aimed to evaluate the effects of hepatoprotective agents added to diets containing different energy sources on the metabolic status of lactating dairy cows in confinement. Sixteen Holstein × Gir crossbred midlactation cows with a body weight of 553 ± 85 kg were included in this feeding trial. These animals were arranged in a 4 × 4 Latin square experimental design. A 2 × 2 factorial arrangement was employed in this feeding experiment. Experimental treatments consisted of the administration of diets supplemented with a hepatoprotectant and diets without hepatoprotectant. These diets contained varying amounts of ground corn or citrus pulp as energy sources. Serum markers for energy metabolism and proteins were evaluated and liver enzymes were measured. Blood samples were collected in the morning before (0 h) and 4 h after the animals were fed these diets. There was no interaction between the hepatoprotective agent and the dietary energy sources for the metabolic status variables. Ground corn as an energy source yielded higher serum concentrations of glucose, HDL (high-density lipoprotein) cholesterol, and globulins, whereas b-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA), total cholesterol, albumin, and aspartate aminotransferase (AST) yielded the highest concentrations in diets containing citrus pulp. There was interaction between time and hepatoprotective agent in serum LDL (low-density lipoprotein) cholesterol concentration. The present study shows that ground corn diets increased the synthesis of glucogenic nutrients, whereas citrus pulp used as an energy source altered the lipid status of lactating cows. The hepatoprotective agent increased postprandial serum LDL cholesterol levels.
Keywords: Blood parameters; Dairy cows; Glucose; Lipid profile; Liver.