Bovis ISSN 2398-2993

Magnesium: overview

Synonym(s): hypomagnesemia, hypermagnesemia, staggers

Contributor(s): Alastair Macrae , Julia Moorhouse

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Introduction

  • The average annual incidence of clinical acute hypomagnesemia (staggers) in UK dairy herds is under 1%.
  • However given that 30% of affected animals will die, this represents a conservative cost of approximately £2 million per annum in the UK (assumes 0.1% incidence of acute hypomagnesaemia in UK dairy herd of 1.9 million cows (1900 cows affected), 30% mortality (570 deaths), cost of a fatality £3,000).
  • Losses due to subclinical (or chronic) hypomagnesemia may result from depression of dry matter intakes, milk yields and body condition, and increased susceptibility to diseases such as milk fever. These will often go undetected unless a case of acute hypomagnesaemia occurs, or routine monitoring by blood sampling is used to detect the problem.
  • Classically, slightly more cases of acute hypomagnesemia occur at grazing in the spring and autumn. However, cases can occur at any time of the year when magnesium intakes are not sufficient to meet demands, including during housing and in dry cows.
  • It also occurs in beef suckler cows, especially when only fed poor quality forages. Lack of proper mineral supplementation in beef cattle will often predispose to hypomagnesemia.
  • Although there are well-established methods for the prevention and control of hypomagnesemia, there may be additional problems with the availability and absorption of magnesium from the diet, as well as practical and economic difficulties in implementing control measures.

Overview of magnesium metabolism

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Factors affecting the availability of magnesium to the cow

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Signs of magnesium deficiency/toxicity

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Magnesium supplementation

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General preventative measures for the prevention of hypomagnesaemia

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMed Resource.
  • Foster A, Livesey C & Edwards G (2007) Magnesium disorders in ruminants. In Practice 29, pp 534-539.
  • Kelly J (1988) Magnesium and milk fever. In Practice 10 pp 168-170.
  • Martens H &Schweigel M (2000) Pathophysiology of grass tetany and other hypomagnesemias: implications for clinical management. Veterinary Clinics of North America: Food Animal Practice 16 pp 339-36 PubMed.
  • Whitaker D A, Macrae A I & Burrough E (2004) Disposal and disease rates in British dairy herds between April 1998 and March 2002. The Veterinary Record 155, pp 43-7 PubMed.

Other sources of information

  • Suttle N (2010) Magnesium. In: Mineral Nutrition of Livestock. 4th Edn. Ed: Suttle, N. CABI, Wallingford, Oxford.pp 92-121.


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