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https://hdl.handle.net/1959.11/28945
Title: | Do calcium and magnesium deficiencies in reproducing ewes contribute to high lamb mortality? | Contributor(s): | Friend, Michael A (author); Bhanugopan, Marie S (author); McGrath, Shawn R (author); Hocking Edwards, Janelle (author); Hancock, Serina (author); Loudon, Kate (author); Miller, David (author); McGilchrist, Peter (author) ; Refshauge, Gordon (author); Robertson, Susan M (author); Thompson, Andrew N (author); Masters, David G (author) | Publication Date: | 2020 | DOI: | 10.1071/AN17588 | Handle Link: | https://hdl.handle.net/1959.11/28945 | Abstract: | High lamb mortality continues to be a significant economic and welfare problem within the Australian sheep industry, with 20-30% of lambs born in commercial flocks dying mostly within 3 days of birth. Clinical hypocalcaemia and hypomagnesaemia cause ewe mortality, and, subsequently, either fetal or lamb death, but it is not known whether subclinical deficiencies of calcium (Ca) and magnesium (Mg) compromise lamb survival. This review considers the potential mechanisms through which Ca and Mg deficiencies may influence lamb survival, and factors influencing the risk of deficiency. Pastures grazed by lambing ewes may be marginal in calcium (Ca; <4 g/kg DM) and magnesium (Mg; <0.9 g/kg DM) but also have a high dietary cation-anion difference (>12 meq/100 g DM) and high concentrations of potassium (K; >30 g/kg DM) and nitrogen. In young cereal crops, sodium concentrations are also often low (<0.9 g/kg DM). This combination of minerals and other nutrients creates an imbalance in supply and increases susceptibility to acute Ca (hypocalcaemia) and Mg (hypomagnesaemia) deficiency. Calcium is required for smooth muscle function and has a direct role in uterine contraction, so may influence the duration of parturition. Low Ca and Mg intake both influence insulin release and sensitivity, low Mg results in poor glycaemic control and insulin resistance by impairing both insulin secretion and its action on peripheral tissues, also potentially altering the duration of parturition as well as risk of metabolic disease. Magnesium is also a neuroprotectant that slows the neuronal damage during hypoxia and has been linked with thermogenesis in offspring and increased immunoglobulins in colostrum. These functions indicate potential importance in improving the ease of parturition and improved ability of the newborn lamb to thermoregulate and survive after birth. Subclinical Ca and Mg deficiencies commonly occur in 20% of lambing ewes grazing temperate pastures, so further studies are warranted to investigate whether correction of these deficiencies can improve lamb survival. | Publication Type: | Journal Article | Source of Publication: | Animal Production Science, 60(6), p. 733-751 | Publisher: | CSIRO Publishing | Place of Publication: | Australia | ISSN: | 1836-5787 1836-0939 |
Fields of Research (FoR) 2008: | 070204 Animal Nutrition | Fields of Research (FoR) 2020: | 300303 Animal nutrition | Socio-Economic Objective (SEO) 2008: | 830310 Sheep - Meat 830311 Sheep - Wool |
Socio-Economic Objective (SEO) 2020: | 100412 Sheep for meat 100413 Sheep for wool |
Peer Reviewed: | Yes | HERDC Category Description: | C1 Refereed Article in a Scholarly Journal |
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Appears in Collections: | Journal Article School of Environmental and Rural Science |
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