Calcium and magnesium supplementation of ewes grazing pasture did not improve lamb survival

Context Clinical deficiencies of calcium and magnesium may result in the metabolic disorders hypocalcaemia hypomagnesaemia, resulting ewe lamb mortality. However, contribution subclinical to perinatal mortality grazing flocks is unclear. Aims To test hypothesis that supplementation during lambing period would increase survival marking age. Methods In 2017, an on-farm study used five across New South Wales, Australia Western Australia. On each farm, twin-bearing mature Merino ewes (n = 400–600) pasture were allocated two replicates control supplemented treatments. The groups offered 30 g/ewe per day a loose lick containing chloride (MgCl2(H2O)6), sulfate (CaSO4·(H2O)2, salt (NaCl), ratio 12.5:32.5:55.0, designed have low dietary cation–anion difference (−390 meq/100 g). A second was conducted 2018 on one farm form supplement. This three treatments: control; low-dietary supplement as 2017; standard lime, Causmag (calcined MgO) mix (ratio 1:1:1). Mature composite 600) those minerals for last month pregnancy period. Blood urine samples collected both experiments analyses mineral concentrations. Key results 2017 study, only consumed >10 day, did not age these flocks. mean consumption 18 or 20 day. Of non-supplemented ewes, 61% deficient plasma (≤90 mg/L) 17% (≤18 at Day 140 after start joining. Lamb increased by 77 ± 3.8% Conclusions Calcium survival. Implications supplementation; however, evaluation under wider range conditions with adequate intake required.