HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Duncan, C. W. Articles by Huffman, C. F. Search for Related Content PubMed Articles by Duncan, C. W. Articles by Huffman, C. F.

Studies on the Composition of Bovine Blood. II. Seasonal Variations in the Level of Magnesium in the Blood Plasma of Growing Dairy Calves

From the Chemistry Section and Section of Dairy Husbandry of the Michigan Agricultural Experiment Station, East Lansing, Michigan

ABSTRACT

The results of this study, based on the repeated determination of plasma magnesium in 2,286 samples of blood from 107 calves, show the changes in concentration of magnesium for the various calendar months of the year and the marked seasonal drop that occurred during the transition from winter to summer conditions when the calves had to adjust themselves rapidly to new weather conditions.

A number of direct environmental factors, the temperature, sunshine, precipitation, barometric pressure and relative humidity, have been considered and linear correlations have been indicated to show some apparent relationships with plasma magnesium but none have been found wholly satisfactory in explaining why these alterations occur in the animal body. Lower plasma magnesium values were associated with those months during which there were more than eight hours of sunshine per day and when the mean and maximum mean temperatures were above 55° and 70° F., respectively.

The changes in concentration cannot be ascribed to the effect of solar radiation because the magnesium values obtained from the young calves which did not have access to direct sunlight responded in the same manner as those which were turned out to pasture.

The results of the study suggest a striking parallelism in the concentration of magnesium to changes in season. Periods of high and periods of low concentrations not attributable to age or to the ingestion of food are definitely indicated.