Magnesium metabolism in the dairy cow V. Experimental observations with a purified diet low in magnesium

Publisher Website
Google Scholar
Abstract
1. An artificial diet low in magnesium (0·01–0·02% of the dry matter), and providing about 0·5 g. magnesium daily, was prepared from paper pulp, maize gluten, magnesium-free minerals and vitamins A and D and used in experimental studies with two non-lactating cows.2. The omission of a dietary supplement of magnesium oxide (5 g./day) caused a rapid fall in the excretion of magnesium in the urine, from values of 1–2 g./day to virtually zero within about 4 days. There was a similar rapid fall in the concentration of magnesium in the serum, from about 2·7 to 2·0 mg./lOO ml., and then a slow fall to between 1·0 and 1·5 mg./lOO ml. after 12 days. Faecal excretion of magnesium was also reduced but the faecal loss continued at about 1·0 g./day after 2–3 days on the low magnesium diet.3. The availability of the magnesium of various salts was determined by giving them as supplements to the basal diet and measuring the increase in the excretion of magnesium in the urine. The mean value was 26·2% in one cow and 34·5% in the other, a highly significant difference (P< 0·01). The availabilities of the oxide, nitrate, acetate and lactate were similar, but the citrate gave a higher value and the sulphate, silicate and, in one cow, the chloride a lower value.
Keywords

This publication has 5 references indexed in Scilit: