Relationship between blood selenium concentration or glutathione peroxidase activity, and milk selenium concentrations in New Zealand dairy cows

Aim: To determine the relationships between blood selenium (Se) concentrati ons or glutathione peroxidase activity (GSH-Px), and milk Se concentrations in dairy cows. Methods: Seventy-two Friesian dairy cows were either untreated or injected with 0.5, 1.0 or 2.0 mg Se/kg liveweight as barium selenate (BaSeO4) formul ations, resulting in 6 groups of animals with mean blood Se concentrations that varied from 212 to 2272 nmol/l. Milk samples were collected on Days 10 4 and 188, and blood samples were collected prior to treatment and on Days 41, 76, 104, 188, 244, and 292 after Se injection. Results: Significant quadratic relationships between blood Se and milk Se c oncentrations, as well as blood GSH-Px activity and milk Se concentrations, were evident at Days 104 and 188. Using combined data, these were represen ted by the equations: milk Se = 27.3 + 0.073 blood Se -0.00001 (blood Se)(2 ); R-2=0.79, p<0.005, and; milk Se = 34.8 + 4.39 GSH-Px -0.068 (GSH-Px)(2); R-2=0.79, p<0005 Conclusions: The Se status of dairy cows can be assessed from milk Se conce ntrations. Clinical significance: Bulk-tank milk Se concentrations could be evaluated as a method to assess the Se status of dairy herds.