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Some effects of conservation of grass upon magnesium metabolism in sheep

Published online by Cambridge University Press:  27 March 2009

G. Powley
Affiliation:
Department of Animal Physiology and Nutrition, University of Leeds
C. L. Johnson
Affiliation:
Department of Animal Physiology and Nutrition, University of Leeds

Summary

Metabolism trials were conducted with sheep to study the effects of conservation of herbage as silage, frozen or artificially dried grass upon the magnesium and calcium availabilities in the conserved products.

When the diet was changed, approximately isomagnesaemically, from hay and barley to each of the conserved products, there was a highly significant (P < 0·001) decrease in the plasma magnesium concentration. However, the plasma magnesium concentrations of the ewes eating the artificially dried grass were significantly lower (P < 0·05) than the corresponding values when they ate the frozen grass or silage. No changes were seen in the plasma calcium concentrations.

The apparent availability of magnesium in the silage was significantly higher (P < 0·05) than that in the frozen and artificially dried grasses. Also, the apparent availability of magnesium and calcium was lower in the dried grass than in the other two products, whilst the retention of both magnesium and calcium was significantly lower (P < 0–05) when the dried grass was eaten as compared with the frozen grass and silage. The percentage urinary loss of magnesium was greatest on the silage and least on the dried-grass diet.

It was concluded that artificially drying grass caused a reduction in magnesium availability.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1977

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