Improved fertility in dairy cows after treatment with selenium pellets

Dairy cows on 3 New South Wales dairy farms with herd mean blood glutathione peroxidase (GSH-Px) activities of less than 70 U/g haemoglobin, showed a significant improvement in first service conception rates following treatment with oral selenium pellets. Treated cows had significantly higher blood GSH-Px activities compared with control cows, with a lag phase of 4 to 5 months to reach peak mean levels of 88 to 159 U/g haemoglobin.