Parturient Paresis. VI. Some Changes in the Urinary Excretion of Certain Constituents at Parturition and their Possible Association with Changes in the Blood Picture

Abstract

Studies on the blood levels and urinary excretion of Ca, inorganic P, Mg and citric acid at parturition were made on 8 Jersey cows. Two cows calved normally, 4 developed milk fever, and 2 cows, while they did not develop milk fever, were markedly unsteady following parturition and were called "borderline" cows. Urinary Ca excretion was quite variable at parturition. There was no consistent or appreciable variation between the normal, milk fever, and borderline cows. Neither did a relation exist between Ca losses via urinary channels and changes in the blood Ca. Urinary Mg losses were much more extensive between days 16 and 3 prepartum in the cows which developed milk fever than in the normal cows. The borderline cows were intermediate between the other groups in this respect. All 3 groups were excreting essentially the same amts. of Mg via the urinary route on the day of parturition. Following parturition, the Mg excretion by the normal group increased, and by days 5 and 10 postpartum the normal cows were excreting more urinary Mg than either the milk fever or borderline groups. In general, blood serum Mg seemed to rise in the milk fever and borderline cows as the urinary excretion of this constituent decreased, but this relation was not consistent throughout the trial. There was approx. 5 times as much citric acid excreted in the urine of the cows which subsequently developed milk fever on days 3, 2 and 1 prepartum as was excreted in the urine of the normal or borderline cows on those days. The high levels of citric acid excretion prepartum were accompanied by levels of blood serum citric in the milk fever cows which were higher than normal. Very small and consistent amounts of inorganic P were excreted by all of the cows prepartum, with no group differences. In general, the pospartal excretion was also very small. There was no apparent relation between blood plasma levels of inorganic P and the urinary excretion of this constituent.