放牧牛のセレン栄養状態およびセレン補給の効果

抄録

Thirty seven Japanese Black breed cows which pastured year-round from birth were divided in two groups. Each of 18 cows received two selenium (Se) pellets, each weighing 30 g and containing 90 % iron grit and 10 % elemental Se. The remaining 19 cows served as control. Blood were sampled seasonally for two years and assayed for blood Se concentration, blood glutathione peroxidase activity (GSH-Px), plasma α-tocopherol concentration (α-Toc) and plasma creatine phosphokinase activity.

The Se content of pasture surveyed showed fairly low values ranging from 0.014 to 0.019 ppm in dry matter. Blood Se as well as blood GSH-Px in control cows were close to the marginal one which is borderline to deficient state. Despite the low status of Se in control cows, no clinical signs of deficiency desease observed throughout the experiment. Ruminal Se pellets restored the Se status of grazing cows. Blood Se and GSH-Px were significantly higher in Se treated cows than control cows and the levels were maintained adequately at least up to two years after pellets treatment. There was no influence of pellets treatment on plasma α-Toc levels. Plasma α-Toc level were kept fairly high in both Se treated cows and control cows.

The Se dosing technique of ruminal Se pellet was useful and highly effective in raising Se status of grazing cows.