Graduate Thesis Or Dissertation
 

Interrelationships of magnesium, potassium, and nitrogen in hypomagnesemia

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/fb494c16n

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  • The objective of this study was to investigate the influence of dietary magnesium, potassium and nitrogen on hypomagnesemia. Rats and dairy cattle were used as experimental animals. In the rat experiments, 270 albino rats, Mus norvegicus albinus, were used on 27 synthetic diets consisting of three levels each of casein (18, 24 and 30 percent of the diet, as nitrogen source), magnesium (400, 200 and 50 mg/kg of the diet) and potassium (1.8, 3.6 and 7.2 g/kg of the diet). The rats weighed 50-60 g at the start of the experiment. The feeding periods were four and eight weeks. The study with dairy cattle was a grazing survey to investigate the relationships between certain constituents of pasture forages and serum magnesium in early pasturing season which is a critical time for hypomagnesemic tetany. Sixty Holstein and Jersey cows were involved in the study. An atomic absorption spectrophotometer was used for the determinations of minerals in serum, tissue and forage samples. Skin lesions were observed in the rats fed 50 mg/kg magnesium diets and increased in severity with the increase in dietary nitrogen and with the extension of the experimental period from four to eight weeks. Increasing levels of dietary nitrogen and potassium and decreasing levels of magnesium highly significantly (P < 0.01) decreased the magnesium concentration of serum. The mean serum magnesium values were found to be 2.51, 2.18 and 0.95 mg/100 ml with dietary magnesium values of 400, 200 and 50 mg/kg, respectively. The interactions between and among periods, nitrogen and magnesium in hypo-magnesemia were highly significant (P < 0.01). The dietary potassium, on the other hand, showed a significant (P < 0.05) interaction only with magnesium. Serum calcium concentration was increased by the increase in dietary nitrogen and by the decrease in dietary magnesium; however, such increase was within what might be called a physiologically "normal" range. It was unaffected by the increase of dietary potassium. The change in the dietary magnesium did not affect the serum potassium concentration. The magnesium content of bone was markedly decreased by the increase of dietary nitrogen and potassium and by the decrease of dietary magnesium. A high correlation coefficient was found (r = 0.978) between bone and serum magnesium concentrations, indicating a close association between the two. The hypomagnesemia, on the other hand, was not accompanied by a significant reduction in muscle magnesium. In the grazing experiment, after five weeks of pasturing, the mean serum concentrations of cows was decreased and serum calcium and potassium values were increased significantly. It may be concluded that the hypomagnesemic condition in animals is not a simple deficiency or a simple interference of another factor, but a complex one. With this consideration, it may be suggested that a variety of preventive measures should be taken against the various potential factors which could induce hypomagnesemia when cattle are turned into pasture in the early spring.
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