Effects of varying the amounts of dietary calcium on selenium metabolism in dairy calves.

Influence of dietary Ca on Se metabolism was studied with 16 intact male Holstein calves averaging 86 kg. Calves were assigned randomly and fed one of four diets containing, .17, .67, 1.31, and 2.35% Ca at 3% of their body weight for 4 wk. The diets contained .062 ppm Se and .34% P. Four days prior to the end of the experiment, calves were dosed orally with radioactive 75Se. Dietary Ca had no significant effect on 75Se absorption. There was a slight curvilinear relationship between apparent 75Se absorption and dietary Ca intakes. Urinary excretion of 75Se and stable Se tended to decrease with increasing dietary Ca, but differences were not significant. No significant differences were found in concentration of 75Se in several tissues. Kidney and liver had the highest concentration with that in kidney being about four times that of liver. Apparent 75Se absorption was decreased 10 to 6%, respectively, in calves fed extremely low and high amounts of Ca, compared with those receiving the requirement (.67% Ca). These small reductions along with a small R2 suggest that dietary Ca probably is of little practical importance relative to Se metabolism in calves.