Calcium and magnesium status of pregnant ewes grazing southern Australian pastures

Janelle E. Hocking Edwards, David G. Masters, Emma Winslow, Serina Hancock, Andrew N. Thompson, Gordon Refshauge, Shawn R. McGrath, Susan M. Robertson, Marie S. Bhanugopan, Michael A. Friend

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

During pregnancy, ewes graze pastures that may be marginal in calcium (Ca) and magnesium (Mg), and may also be low in sodium (Na) and high in potassium (K), with a high dietary cation-anion difference. Such pastures may increase susceptibility to hypocalcaemia and hypomagnesaemia, leading to lamb losses. Clinical hypocalcaemia and hypomagnesaemia do occur in Australian sheep- however, it is unknown whether subclinical forms of these disorders compromise ewe or lamb health and survival. The present study monitored the Ca and Mg status of ewes in late pregnancy, so as to evaluate the risk of subclinical mineral disorders in ewes grazing typical southern Australian pastures. Calcium and Mg concentrations in pasture, ewe plasma and urine were monitored in 15 flocks in southern Australia. Mineral concentrations in pasture did not indicate a widespread risk of Ca or Mg deficiency- however, urinary pH and Ca and Mg concentrations in the plasma and urine of the pregnant ewes were not entirely consistent with the expectations from pasture analysis. Urine pH was above 7 on all properties and 87.5% of properties had a mean Ca in urine below the adequate concentration of 1 μmol/mosmol. The mean plasma Ca concentration was below adequate (<90 mg/L) on only one farm but five farms had more than 20% of ewes with below adequate Ca in plasma. In addition, although average farm concentrations of plasma and urine Mg indicated adequate Mg status of the ewes (>18 mg/L), more than 20% of ewes on six farms had below adequate concentrations of plasma Mg. Only one-third of the farms had 100% of ewes measured with adequate concentrations of plasma Ca (4/15) or Mg (5/15). The mineral concentrations in pre-lambing blood and urine samples suggested that a significant number of animals grazing southern Australian pastures during winter may be at risk of subclinical hypocalcaemia and hypomagnesaemia.
Original languageEnglish
Pages (from-to)1515-1521
Number of pages7
JournalAnimal Production Science
Volume58
Issue number8
DOIs
Publication statusPublished - Apr 2018

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Magnesium
ewes
magnesium
pastures
grazing
Calcium
calcium
hypomagnesemia
urine
hypocalcemia
Urine
Hypocalcemia
Minerals
mineral content
lambs
dietary cation anion difference
pregnancy
Magnesium Deficiency
Pregnancy
farms

Cite this

Hocking Edwards, J. E., Masters, D. G., Winslow, E., Hancock, S., Thompson, A. N., Refshauge, G., ... Friend, M. A. (2018). Calcium and magnesium status of pregnant ewes grazing southern Australian pastures. Animal Production Science, 58(8), 1515-1521. https://doi.org/10.1071/AN17766
Hocking Edwards, Janelle E. ; Masters, David G. ; Winslow, Emma ; Hancock, Serina ; Thompson, Andrew N. ; Refshauge, Gordon ; McGrath, Shawn R. ; Robertson, Susan M. ; Bhanugopan, Marie S. ; Friend, Michael A. / Calcium and magnesium status of pregnant ewes grazing southern Australian pastures. In: Animal Production Science. 2018 ; Vol. 58, No. 8. pp. 1515-1521.
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Calcium and magnesium status of pregnant ewes grazing southern Australian pastures. / Hocking Edwards, Janelle E.; Masters, David G.; Winslow, Emma; Hancock, Serina; Thompson, Andrew N.; Refshauge, Gordon; McGrath, Shawn R.; Robertson, Susan M.; Bhanugopan, Marie S.; Friend, Michael A.

In: Animal Production Science, Vol. 58, No. 8, 04.2018, p. 1515-1521.

Research output: Contribution to journalArticle

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Hocking Edwards JE, Masters DG, Winslow E, Hancock S, Thompson AN, Refshauge G et al. Calcium and magnesium status of pregnant ewes grazing southern Australian pastures. Animal Production Science. 2018 Apr;58(8):1515-1521. https://doi.org/10.1071/AN17766