University of Tasmania
136538 - Magnesium biofortification of Italian ryegrass via agronomy and breeding as a potential way to reduce grass tetany in grazing ruminants.pdf (1.59 MB)

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

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posted on 2023-05-20, 09:15 authored by Kumssa, DB, Lovatt, JA, Graham, NS, Palmer, S, Hayden, R, Wilson, L, Young, SD, Lark, RM, Beth PenroseBeth Penrose, Ander, EL, Thompson, R, Jiang, LX, Broadley, MR

Aim: Magnesium (Mg) deficiency (known as grass tetany) is a serious metabolic disorder that affects grazing ruminants. We tested whether Mg-fertiliser can increase Mg concentration of Italian ryegrasses (Lolium multiflorum L.) including a cultivar (cv. Bb2067; ‘Magnet’), bred to accumulate larger concentrations of Mg.

Methods: Under controlled environment (CE) conditions, three cultivars (cv. Bb2067, cv. Bb2068, cv. RvP) were grown in low-nutrient compost at six fertiliser rates (0–1500 μM MgCl2.6H2O). Under field conditions, the three cultivars in the CE condition and cv. Alamo were grown at two sites, and four rates of MgSO4 fertiliser application rates (0–200 kg ha−1 MgO). Multiple grass cuts were taken over two-years.

Results: Grass Mg concentration increased with increasing Mg-fertiliser application rates in all cultivars and conditions. Under field conditions, cv. Bb2067 had 11–73% greater grass Mg concentration and smaller forage tetany index (FTI) than other cultivars across the Mg-fertiliser application rates, sites and cuts. Grass dry matter (DM) yield of cv. Bb2067 was significantly (p < 0.05) smaller than cv. Alamo. The effect of Mg-fertiliser rate on DM yield was not significant (p ≥ 0.05).

Conclusions: Biofortification of grass with Mg through breeding and agronomy can improve the forage Mg concentration for grazing ruminants, even in high-growth spring grass conditions when hypomagnesaemia is most prevalent. Response to agronomic biofortification varied with cultivar, Mg-fertiliser rate, site and weather. The cost:benefit of these approaches and farmer acceptability, and the impact on cattle and sheep grazing on grasses biofortified with Mg requires further investigation.


Publication title

Plant and Soil






Tasmanian Institute of Agriculture (TIA)


Kluwer Academic Publ

Place of publication

Van Godewijckstraat 30, Dordrecht, Netherlands, 3311 Gz

Rights statement

Copyright 2019 the authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0)

Repository Status

  • Open

Socio-economic Objectives

Beef cattle; Dairy cattle; Sheep for meat

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