Breeding grass varieties with increased

magnesium content to prevent

hypomagnesaemia in ruminants Lovatt, J.A. 1, Ander, E.L. 2, Broadley, M.R. 3, Bone P. 4, Crout, N.M.J. 3, Graham,

N. 3, Hayden, R. 3, Kendall, N.R.5, Kumssa, D.B. 3, Lark, R.M.6, Lovatt, A.C.1,

Palmer, S. 1, Penrose, B.7, L. Skot, L. 1, Thomson, R.8, Wilson, P. 3, Young, S.D.3 1Prifysgol Aberystwyth University, Institute of Biological, Environmental and Rural

Sciences (IBERS), Plas Gogerddan,, Aberystwyth, SY23 3EE, UK; 2British Geological Survey, Inorganic Geochemistry, Centre for Environmental

Geochemistry, Keyworth,, Nottinghamshire, NG12 5GG, UK; 3University of Nottingham, School of Biosciences, Sutton Bonington Campus,

Loughborough, LE12 5RD, UK; 4Ruminant Mineral Consultancy, 39 Stratton Heights, Cirencester GL7 2RH, UK; 5University of Nottingham, Environmental Statistics, Sutton Bonington Campus,

Loughborough, LE12 5RD, UK; 6British Geological Survey, Environmental Statistics, Keyworth,, Nottinghamshire, NG12

5GG, UK; 7University of Tasmania, School of Land & Food, Private Bag 98 , HOBART Tas 7001,

Australia; 8Science and Advice for Scottish Agriculture (SASA), Roddinglaw Road, Edinburgh EH12

9FJ, UK.

Understanding spatial and management controls

on magnesium deficiency in ruminants

“Magnesium Network (MAG-NET): Integrating

Soil-Crop-Animal Pathways to Improve Ruminant

Health” (2016–2020) funded by the Sustainable

Agriculture Research & Innovation Club (SARIC)

Industry partners / collaborators / advice

Jon Telfer

Peter Scott

Paul Billings

David Black

Pete Bone

Magnesium

• A flammable metal

• 4th most common

• Essential for plant and

animal life

– 300 enzymes require Mg

– Mg needed in chlorophyll

Hypomagnesaemia – Grass

Staggers – Grass Tetany

• Caused by a deficiency of

magnesium (Mg) in the

blood. Can be rapidly fatal in

ruminants and a common

cause of sudden death.

• Stock have a poor capability

to store magnesium in the

body and must have

sufficient magnesium on a

daily basis to prevent

deficiency and subsequent

disease.

Hypomagnesaemia

Grass staggers or Grass tetany

• Widespread with high

fatality rate

• Commonest in spring and

autumn

• Can also affect intake &

milk yield

Prevented by supplying additional magnesium

Copyright © NADIS 2007

How common is it?

• Average acute annual incidence = 1%

• Chronic disease unrecognised

– Possibly 3 – 4% in dairy

• Rapid progression

Prevention with dusting/supplements

bullets possible but not 100% reliable

Aims of Project

1. Predictive maps of hypomagnesaemia-

sensitive regions for England, N. Ireland and

Wales.

2. Novel genetic markers and crop management

strategies to increase leaf Mg concentration in

forage grasses

3. A multi-scale decision support tool for forage

nutrient management

Magnesium Network (MAG-NET): Integrating Soil-Crop-

Animal Pathways to Improve Ruminant Health

Project delivery via four discipline-based work packages

(WPs):

1. Mapping and modelling hypomagnesaemia risks

2. Farm / veterinary audit of magnesium use,

knowledge and opinion

3. Crop breeding and management experiments

4. Decision support

Magnet – the variety

• We bred a high

magnesium

variety of Italian

ryegrass in the

1980’s called

Magnet

1984 - IBERS bred a high-magnesium Italian

ryegrass variety to supply additional magnesium

1984

Magnet (Bb2067) successfully controlled

hypomagnesaemia under grazing

(Moseley and Baker. Grass & Forage Science (1991) 46, 375-380)

Magnet

(Bb2067)

RvP -control

Total number on treatment 120 120

Number of clinical cases 3 25

Fatalities 0 18

% Incidence 2.5 21

% Fatalities 0 15

Incidence of hypomagnesaemia in ewes

grazing Italian ryegrass cultivars

For a variety to be marketed… • National List/Recommended Listing (without that it

cannot be marketed)

– Value for Cultivation and Use (VCU)

• VCU traits (depend upon species) – predominantly agronomic, easy to measure and inexpensive

– Yield, Disease resistance, Quality (DMD)

• Distinct, Uniform and Stable (DUS) – must be different from any other variety (varieties can fail at this stage)

Improved animal survival – NOT commercialised

1984

8

9

10

11

12

13

14

15

16

17

18

Aberystwyth Year 1 Aberystwyth Year 2 Edinburgh Year 1 Edinburgh Year 2

Total Annual DM Yield in t/ha

Magnet RvP

33 years later………

Controlled Environment experiment

3 grass

varieties

Bb 2067

Bb 2068

Bb 2235

6 levels of Mg fertiliser

(mM) based on

Hoagland’s solution

Control

0.075

0.1875

0.375(1x)

0.75

1.5

24 reps

Controlled Environment experiment

Field experiments

Four grass varieties

Alamo (modern variety)

Bb2067 (high Mg)

Bb2068 (low Mg)

RvP (control)

Two locations

Aberystwyth (Gogerddan)

Edinburgh (Gogar)

Four rates of MgSO4 as an

elemental Mg equivalent (kg ha-1)

Control (0)

30.15

60.3

120.6

4 reps

Trials established August 2016

7 harvests per annum

B565/16-MG trial 1st Harvest Year – 2017 (Aberystwyth) (Percentage figures in Red = significantly lower & in Blue = significantly higher than the relevant control)

Combined Management - Dry Matter Yield

Variety Cut 1 Cut 2 Cut 3 Cut 4 Cut 5 Cut 6 Cut 7 Total GCov

26-Apr-17 31-May-17 5-Jul-17 31-Jul-17 30-Aug-17 26-Sep-17 30-Oct-2017

Bb2067_2 6.65 104 4.71 101 4.50 89 1.96 71 1.46 80 0.86 83 0.79 80 20.14 93 31.6

Bb2068_2 6.59 103 4.67 100 4.75 94 2.09 75 1.40 77 0.85 82 0.90 91 20.35 93 31.6

RvP - Control 6.38 100 4.67 100 5.08 100 2.78 100 1.82 100 1.04 100 0.99 100 21.77 100 35.5

Alamo 6.61 104 4.75 102 5.49 108 3.11 112 2.07 114 1.25 120 1.06 107 23.28 107 43.9

NS NS *** *** *** *** *** *** ***

SED 0.22 0.14 0.11 0.08 0.04 0.03 0.04 0.34 1.28

LSD05 (cf. RvP) 0.22 4 0.15 6 0.09 5 0.06 6 0.07 8 0.69 3 2.57

Fertiliser Treatment

MgSO4_0 6.62 100 4.76 100 4.91 100 2.45 100 1.67 100 0.99 100 0.96 100 21.40 100 35.6

MgSO4_1 6.43 97 4.67 98 4.96 101 2.50 102 1.69 101 0.99 100 0.90 94 21.24 99 36.4

MgSO4_2 6.58 99 4.69 99 4.97 101 2.46 100 1.69 101 1.01 102 0.96 100 21.40 100 36.1

MgSO4_3 6.60 100 4.69 99 4.98 101 2.52 103 1.68 101 1.01 102 0.91 95 21.48 100 34.5

NS NS NS NS NS NS NS NS NS

SED 0.22 0.14 0.11 0.08 0.04 0.03 0.04 0.34 1.28

LSD05

Fertiliser * Variety * NS NS NS NS NS NS NS

B565/16-MS trial 1st Harvest Year – 2017 (Edinburgh Courtesy of SASA)

(Percentage figures in Red = significantly lower & in Blue = significantly higher than the relevant control)

Combined Management - Dry Matter Yield

Variety Cut 1 Cut 2 Cut 3 Cut 4 Cut 5 Cut 6 Cut 7 Total GCov 04-Apr-17 24-May-17 26-Jun-17 27-Jul-17 28-Aug-17 26-Sep-17 31-Oct-17

Bb2067_2 2.79 97 5.74 104 4.80 95 2.62 94 1.89 92 1.11 103 0.84 102 19.79 98 49.6

Bb2068_2 2.83 98 5.57 101 4.86 96 2.64 94 2.03 99 1.07 99 0.78 95 19.78 98 41.6

RvP - Control 2.88 100 5.53 100 5.05 100 2.80 100 2.05 100 1.08 100 0.82 100 20.21 100 42.5

Alamo 3.30 115 5.59 101 5.15 102 2.88 103 2.09 102 1.26 117 0.90 110 21.17 105 57.5

*** NS ** *** * *** *** *** ***

SED 0.06 0.12 0.11 0.07 0.06 0.03 0.02 0.29 1.94

LSD05 (cf. RvP) 0.12 4 0.21 4 0.13 5 0.12 6 0.07 6 0.05 6 0.59 3 3.91

Fertiliser Treatment

MgSO4_0 3.00 100 5.74 100 5.07 100 2.74 100 1.99 100 1.15 100 0.82 100 20.51 100 46.8

MgSO4_1 2.94 98 5.53 96 4.84 95 2.73 100 2.05 103 1.12 97 0.85 104 20.06 98 47.8

MgSO4_2 2.90 97 5.65 98 4.91 97 2.78 101 1.99 100 1.14 99 0.83 101 20.20 98 48.8

MgSO4_3 2.95 98 5.51 96 5.03 99 2.70 99 2.04 103 1.12 97 0.84 102 20.19 98 47.8

NS NS NS NS NS NS NS NS NS

SED 0.06 0.12 0.11 0.07 0.06 0.03 0.02 0.29 1.94

LSD05

Fertiliser * Variety NS NS NS NS NS NS

Aberystwyth trials

SASA trials

Alamo and Bb2067 at 120.6 kg/Ha

Tetany index

Tetany = K (moles/kg DW) / (Mg (moles/kg DW)*2 + Ca (moles/kg DW)*2

Controlled Environment experiment

K response • Same design as for Mg response

• 6 levels of K and 3 levels of Mg

• Leaf material analysed

• Plants treated will be harvested soon

Controlled Environment experiment

marker identification

•Plants used from initial Mg experiment

• Leaf tissue collected, RNA extracted has been extracted

•Pooled samples (6 plants each) from Bb2067 and Bb2068 will be sequenced

• Identify SNPs between 2 lines

•Other individual plants DNA extracted, genotyped for presence of alleles

Manhattan plot of tetany ratio phenotype

in perennial ryegrass intermediate breeding

population

Chromosome

Gene Function Location P value (-log(P))

Haloacid dehalogenase-

like hydrolase

Magnesium ion binding;

function not clear

Unmapped 4.64

Translocase Involved in protein precursor

import into chloroplast

Unmapped 5.43

Protease Do-like2 Chloroplastic serine-type

endopeptidase; cleavage of

photodamaged D1 protein in

photosystem II

Chr 1

19.24 cM

5.02

Peroxidase A2 Peroxidase activity Chr 1

20.26 cM

5.02

Hydrogen transporting

ATP synthase

Thylakoid membrane in

chloroplasts

Chr 1

34.20 cM

4.33

GWAS analysis of tetany ratio phenotype (K/(Ca + Mg))

in F11, F12, F13 breeding population

Diolch yn Fawr

Go raibh maith agat

Thank

You