Relationship between blood selenium concentration or glutathione peroxidase activity, and milk selenium concentrations in New Zealand dairy cows.
OBJECTIVE
To determine the relationships between blood selenium (Se) concentrations 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) formulations, 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 104 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 concentrations, as well as blood GSH-Px activity and milk Se concentrations, were evident at Days 104 and 188. Using combined data, these were represented by the equations: milk Se = 27.3 + 0.073 blood Se -0.00001 (blood Se)2; R2=0.79, p<0.005, and; milk Se = 34.8 + 4.99 GSH-Px -0.068 (GSHPx)2; R2=0.79, p<0.005.


CONCLUSIONS
The Se status of dairy cows can be assessed from milk Se concentrations.


CONCLUSIONS
Bulk-tank milk Se concentrations could be evaluated as a method to assess the Se status of dairy herds.
Grace
N D
ND
AgResearch Grasslands, Private Bag 11008, Palmerston North, New Zealand. neville.grace@agresearch.co.nz
Ankenbauer-Perkins
K L
KL
Alexander
A M
AM
Marchant
R M
RM