Minerals in pastures: calcium and magnesium levels and implications for supplementation

Minerals in pastures: calcium and magnesium levels and implications for supplementation
•A CSU-led project is investigating the link between calcium and magnesium deficiencies and lamb survival
•On-farm surveys in 2016 identified a possible correlation
•A review of the literature has identified a number of mechanisms by which low calcium and magnesium status in ewes could be implicated in low lamb survival
A research project commenced in 2016 to consider the question: “Are deficiencies in calcium and magnesium implicated in lamb mortalities in sheep flocks in Australia?” The research was sponsored by AWI and was headed by the Graham Centre, with collaborators in New South Wales, Victoria, South Australia and Western Australia. In 2016 ewe flocks were monitored during the lambing period, including collection of soil and pasture samples between 30 days prior to lambing and lamb marking, and blood and urine samples from ewes just before lambing and at lamb marking. Survival was monitored on a flock basis. In the local area participating flocks were located at Holbrook, Wagga and Junee. The preliminary results indicate that there may be some relationship between lamb survival and the calcium and magnesium status of ewe flocks.
It is well known that clinical hypocalcaemia (low calcium levels in blood) and hypomagnesaemia (low magnesium levels in blood) can compromise ewe health and result in death. A subsequent literature review has identified mechanisms by which subclinical hypocalcaemia and hypomagnesaemia could have a role in poor survival in new born lambs, or conversely, how supplementation with calcium and magnesium may improve lamb survival. On the basis of this a new experiment will be run in 2017 which will include a comparison of supplementation with calcium and magnesium compared to no supplementation to see if the possible benefits to lamb survival identified from the literature can be demonstrated on farm.