Magnesium biofortification of Italian ryegrass (Lolium multiflorum L.) via agronomy and breeding as a potential way to reduce grass tetany in grazing ruminants

Plasma ionized calcium and magnesium concentrations and prevalence of subclinical hypocalcemia and hypomagnesemia in postpartum grazing Holstein cows from southern Chile

The objective was to determine the plasma concentrations of ionized Ca (iCa) and Mg (iMg) and to establish the prevalence of subclinical hypocalcemia (SCHC) and hypomagnesemia (SCHM) in dairy cows at calving (within 6 hours of parturition) and at 7 days postpartum (pp) in Chilean grazing herds with spring parturitions. Plasma iCa and iMg were assessed using a clinical analyzer. A total of 113 and 175 cows in 18 herds selected at random were sampled at calving and at 7 days pp, respectively. From these 18 herds, 11 herds provided reliable records of lactation number and 8 cows per herd were scored for body condition and sampled at calving and then at 7 days pp. Ionized Ca concentrations for the 18 herds were 0.99 ± 0.16 mmol/L (calving) and 1.01 ± 0.13 mmol/L [7 d pp (P > 0.05)]. Ionized Mg concentrations were 0.58 ± 0.12 mmol/L and 0.51 ± 0.09 mmol/L (P ≤ 0.05). For the 11 herds, iCa concentrations at calving were 1.06 mmol/L (lactation 1), 1.02 mmol/L (lactation 2) and 0.89 mmol/L (lactation ≥ 3), while iMg concentrations were 0.63 mmol/L, 0.60 mmol/L, and 0.61 mmol/L, respectively. Herd prevalence for SCHC (iCa < 1.0 mmol/L) at calving was 64.8%. Prevalence by parity was 40%, 54.5% and 86.7% for lactations 1, 2 and ≥ 3, respectively. Herd prevalence of SCHC on day 7 pp was 30.1%. For SCHM (iMg < 0.52 mmol/L) prevalence was 21.6% and 48.9% at calving and at 7 days pp, respectively.

Increased Provision of Bioavailable Mg through Vegetables Could Significantly Reduce the Growing Health and Economic Burden Caused by Mg Malnutrition

Magnesium (Mg) is an essential mineral nutrient for human health and its deficiency associated with many diseases, including stroke, heart failure, and type 2 diabetes. Vegetables are an important source of dietary Mg for humans. In this study, we quantified vegetable Mg content by a global meat analysis, analyzed human health, and economic impact caused by Mg deficiency. Results revealed that vegetable Mg content showed a large variation with an average value of 19.3 mg 100 g⁻¹ FW. Variation in per capita vegetable-Mg supply in different continents is largely ascribed to continental difference in the amount and the type of vegetables produced. The health and economic loss attributed to Mg deficiency are estimated to be 1.91 million disability-adjusted life years (DALYs) and 15.8 billion dollars (0.14% of GDP), respectively. A scenario analysis indicated that the increasing vegetable production (increased by 8.9% and 20.7% relative to 2017 in 2030 and 2050) and vegetable Mg content (increased by 22% through biofortification) could significantly reduce DALYs (1.24 million years) and economic burden (0.09% of GDP). This study could guide a major re-balance of production practices, species cultivated, and Mg biofortification to provide sufficient vegetable Mg for better human Mg nutrition.

A spatial analysis of lime resources and their potential for improving soil magnesium concentrations and pH in grassland areas of England and Wales

Magnesium (Mg) is essential for animal health. Low Mg status (hypomagnesaemia) can be potentially fatal in ruminants, like cattle and sheep, and is widespread in Europe with economic impacts on farming. The application of Mg-rich agricultural lime products can help to ensure pasture forage consumed by animals contains sufficient Mg and, in areas of low pH, has the dual benefit of reducing soil acidity to levels best suited for grass production. This aim of this study was to determine if Mg-rich lime products could be used in a more effective manner in agricultural production systems. Potential resources of carbonate rocks (limestone, dolostone and chalk) in the UK, and their Mg:Ca status were identified, using datasets from the British Geological Survey (BGS). These data were combined with the locations of agricultural lime quarries, and areas where soils are likely to be deficient in Mg and/or require liming. Areas of potential demand for Mg-rich agricultural lime include areas in south east Wales, the Midlands and North East England. Although, areas where this may be an effective solution to low soil Mg values are restricted by the availability of suitable products. Conversely, areas of low soil pH in England and Wales are often found close to quarries with the ability to supply high Ca limes, suggesting that the low rates of lime use and liming is not due to supply factors. This study provides information that can help to guide on-farm decision making for use of Mg-rich and other lime resources. This could be used in conjunction with other options to reduce risks of Mg deficiency in livestock, and improve soil pH.

Magnesium and calcium overaccumulate in the leaves of a schengen3 mutant of Brassica rapa

Magnesium (Mg) and calcium (Ca) are essential mineral nutrients poorly supplied in many human food systems. In grazing livestock, Mg and Ca deficiencies are costly welfare issues. Here, we report a Brassica rapa loss-of-function schengen3 (sgn3) mutant, braA.sgn3.a-1, which accumulates twice as much Mg and a third more Ca in its leaves. We mapped braA.sgn3.a to a single recessive locus using a forward ionomic screen of chemically mutagenized lines with subsequent backcrossing and linked-read sequencing of second back-crossed, second filial generation (BC2F2) segregants. Confocal imaging revealed a disrupted root endodermal diffusion barrier, consistent with SGN3 encoding a receptor-like kinase required for normal formation of Casparian strips, as reported in thale cress (Arabidopsis thaliana). Analysis of the spatial distribution of elements showed elevated extracellular Mg concentrations in leaves of braA.sgn3.a-1, hypothesized to result from preferential export of excessive Mg from cells to ensure suitable cellular concentrations. This work confirms a conserved role of SGN3 in controlling nutrient homeostasis in B. rapa, and reveals mechanisms by which plants are able to deal with perturbed shoot element concentrations resulting from a "leaky" root endodermal barrier. Characterization of variation in leaf Mg and Ca accumulation across a mutagenized population of B. rapa shows promise for using such populations in breeding programs to increase edible concentrations of essential human and animal nutrients.