EFFECT OF DIETARY SELENIUM SUPPLEMENTATION ON THE PLASMA PROGESTERONECONCENTRATION IN COWS

The effect of selenium (Se) supplementation to the diet on the plasma progesterone concentration was investigated in nonlactating and non-pr egnant cows. Italian ryegrass wafers and concentrates, with or without 0.5 ppm of Se, were fed to cows at a maintenance level. The plasma Se concentrations in the each treatment were 0.047 ppm (-Se) and 0.081 p pm (+Se), respectively. Se supplementation did not affect the length o f the estrous cycle, but it did increase the concentration of plasma p rogesterone in the estrous cycle (P<0.001). These results suggest the possibility that Se contributes to the progesterone production of corp us luteum.