Magnesium does not limit ewe milk production

Authors: Sykes AR
Publication: New Zealand Veterinary Journal, Volume 35, Issue 6, pp 100, Jun 1987
Publisher: Taylor and Francis

Animal type: Livestock, Production animal, Ruminant, Sheep
Subject Terms: Animal production/wastage, Minerals/elememts, Metabolic disease, Disease/defect, Lactation, Milk, Locomotor, Mammary gland/udder, Nervous system/neurology, Nutrition/metabolism
Article class: Correspondence

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Abstract: I wish to draw to the attention of readers my serious reservations about the very strong statement made by the authors Bray, Burton and Cox in their paper “Magnesium supplementation of lactating ewes and lamb growth”. They claim categorically that “magnesium levels below 0.7 m mol/ serum did not limit production” in sheep. This supposes that the supplement provided to half of 26 lactating ewes with serum levels below this threshold was in fact sufficient to reverse the hypomagnesaemia and provide adequate Mg for some critical function. There are very good grounds for believing that the supplement once daily oral administration of 12.5 mg magnesium chloride was totally inadequate to do this. The daily dietary requirement of the particular sheep can be calculated to be between 253.5 g Mg/ day and 10.2 g Mg/d. The supplement provided much less than 1% of this by comparison with either standard. My calculation would suggest that the minimum realistic supplement would have been 1.0-1.5 g Mg/d or 80-120 times the dose given. Comparisons with supplementation work with dairy cattle…

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