Diurnal Variations in Calcium, Magnesium and Citric Acid Levels of the Blood Serum

Abstract

Six Jersey cows were bled at 4-hr. intervals for 3 consecutive days to determine variations in blood serum Ca. There was a significant difference between cows in serum Ca levels, but daily and diurnal variations were not significant. Blood serum citric acid and Mg were detd. on 4 cows bled daily for 9 days and at 6-hr. intervals for 4 of those 9 days. No significant difference existed between cows or between days for serum Mg levels. However, a small but signif- icant diurnal variation existed, being low at the 9:00 A.M. bleeding. Serum citric acid showed significant variation between days and highly significant between cows but no significant diurnal variation.