Forage Macro-Minerals (Ca, P, K, Mg, Na, Cl, S)

and Dairy Cow Requirements

Jim Linn, PhDProfessor Emeritus – University of Minnesota

Milk Specialties GlobalWaconia Farm Supply

Importance of Minerals

AnimalHealthProduction/ReproductionRation cost

Lactating Cow8 to 10% of total

$/cow/day0.75 - 1.00

Close-Up Dry Cow18 – 22% of total

$/cow/day0.75 - 1.00

Nutrient Composition (% DM) of Dairy Rations

Lactating Cow Close-up Dry Cow0

102030405060708090

100

44 39

28 36

17 145.5 7.05.5 3.5

FatMineralsProteinNDFNonFiber CHO

Forage Minerals

Forage mineralsContribute to animal requirementVariability – species, maturity, soils, fertilizationAnimal – Plant Imbalances

Forage Mineral Analysis

NIRS or Wet Chemistry?– NIRS doesn’t measure minerals only C,N,O bonds– Are the minerals reported on NIRS forage tests

accurate?– At the end of the day, when nutritionists have

several rations to formulate, can NIRS predicted forage minerals be used?

NIR Prediction of MineralsHaylage Calibration Data

Mineral Mean SEC RSQ SECV

Ca 1.12 .15 .86 .16

P .34 .04 .61 .04

Mg .32 .05 .69 .05

K 2.66 .32 .81 .32

S .26 .04 .75 .04

Source – Dairyland Labs, Arcadia WI

SEC – Std Error Calibration – lower better (±1 SEC – 67% of values)RSQ – R2 1 = perfect prediction SECV – Prediction validation – lower the better

NIR mineral validity depends on good reference wet chemistry methods and equation(s) development

NIRS Analysis – Forage Minerals

Macro Minerals – – Lactation rations

• Acceptable estimator – Ca, P, K, Mg and S

• Rationale – Most rations over formulated and

supplemented– Small range in P, Mg and S within species– Salt meets Na and Cl req’t

– Dry cow • NIRS not recommended for mineral analysis• Forages are large proportion of diet• Accuracy needed for DCAD and requirements

Trace minerals – NIRS not recommended

Forage Macro MineralsSGS Forage Summary - 2012

Mineral LegumeHaylage

GrassHaylage

Grass 2+Haylage

MixedHaylage

Mix-LegHaylage

Corn Silage

------------------------------- Mean / SD ---------------------------------------------

Ca 1.13 0.67 0.75 1.05 1.33 0.22SD 0.37 0.26 0.25 0.39 0.34 0.07

P 0.29 0.31 0.32 0.29 0.30 0.21SD 0.07 0.08 0.07 .07 0.06 0.03

K 2.46 2.57 2.65 2.45 2.41 0.88SD 0.54 0.78 0.58 0.63 0.54 0.24

Mg 0.27 0.25 0.30 0.26 0.31 0.18SD 0.08 0.08 0.06 0.08 0.07 0.06

Mineral

Mineral bioavailability (%) estimate of forages

NRC 2001

Ca 30 – 35

P 60 – 65

K >85

Mg 15 – 20

S 85 – 90

Na >85

Cl >85

Minerals in Rations of Lactating Dairy Cows

Feed DM (lb) – 85 lb Milk

Haylag

e

Corn Sil

CornBlood

SoyP

assDDGS

Soy-4

6%Ca c

arb

Mono CalMgO

xSa

ltBica

rbK-53%

K-Mg-S

0123456789

101112131415161718

Lb

Feed

DM

52 lb DM17% CP1.18 Mcal ME/lb32% NDF25.5% Starch61 % Forage DM

Macro Minerals for Lactating CowsRequirements vs. Ration Formulation

Mineral 2001 NRC Updated NRC Weiss1

Formulated

------------------------------- % of DM ----------------------------------

Calcium 0.6 – 0.75 0.70 - 0.86 0.9 – 1.0

Phosphorus 0.32 – 0.40 0.38 – 0.48 >0.42

Magnesium 0.20 0.28 0.32 – 0.38

Potassium 1.0 1.15 >1.5

Sodium 0.22 0.25 0.4 – 0.6a

Chloride 0.26 0.30 >0.4b

Sulfur 0.20 0.20 0.25

1 Weiss – Hoards Dairyman Feb 10, 2013a Sodium Buffersb Higher forage concentrations - legume

Calcium Contribution From FeedsLactating cow diet – 0.90% Ca

Haylage

Corn Sil Corn

Blood

SoyP

assDDGS

Soy-4

6%

Ca carb

Mono CalMgO

xSa

lt

Bicarb

K-53%K-M

g-S0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0lb Feed DM

% Ca contribu-tion

lb or %

Phosphorus Contribution From FeedsLactating cow diet – 0.40% P

Haylag

e

Corn Sil

CornBlood

SoyP

assDDGS

Soy-4

6%Ca c

arb

Mono CalMgO

xSa

ltBica

rbK-53%

K-Mg-S

0.0

5.0

10.0

15.0

20.0

25.0

lb or%

lb Feed DM % P contribution

Magnesium Contribution From FeedsLactating cow diet – 0.35% Mg

Haylag

e

Corn Sil

CornBlood

SoyP

assDDGS

Soy-4

6%Ca c

arb

Mono CalMgO

xSa

ltBica

rbK-53%

K-Mg-S

0

5

10

15

20

25

30

35

40lb Feed DM % Mg contribution

lb or%

Potassium

Mineral required in the highest amounts in lactating dairy cows• K balance studies indicate 1.6% K needed in early lactation for positive

balance • Heat stress increases requirement

Forage K >85% available

Potassium Contribution From FeedsLactating cow diet – 1.5% K

Haylag

e

Corn Sil

CornBlood

SoyP

assDDGS

Soy-4

6%Ca c

arb

Mono CalMgO

xSa

ltBica

rbK-53%

K-Mg-S

0

10

20

30

40

50

60% K contribution

lb or%

Sulfur Contribution From FeedsLactating cow diet – 0.28% S

Haylag

e

Corn Sil

CornBlood

SoyP

assDDGS

Soy-4

6%Ca c

arb

Mono CalMgO

xSa

ltBica

rbK-53%

K-Mg-S

0

5

10

15

20

25

30

35% S contribution

lb or%

Sodium and Chloride Contribution From FeedsLactating cow diet – 0.5% Salt

Haylage

Corn Sil Corn

Blood

SoyP

assDDGS

Soy-4

6%

Ca carb

Mono CalMgO

xSa

lt

Bicarb

K-53%K-M

g-S0

10

20

30

40

50

60

lb or%

Ration – 0.5% Na and 0.62% Cl

Minerals in Rations of Close-up Dry Dairy Cows

Close-up Dry Cow Diet28 lb DM/day

lb/cow/day• Grass hay 8.3• Corn silage 13.7• Corn 0.8• Protein 3.8• Macro minerals 1.04• TM/Additives 0.64

Close-up Dry Cow Diet% Macro Mineral from Forage

Calcium

Phosphorus

Magnesu

m

Potassiu

mSu

lfur

Sodium

Chloride

0

10

20

30

40

50

60

70

80 Diet mineral % Ca – 1.60 P – 0.38 Mg – 0.41 S – 0.36 Na – 0.09 Cl – 0.50 DCAD - +0.3

77% Forage diet – 13.7 lb Corn sil + 8.3 lb Grass Hay DM

%

Minerals from Forages in Dry Cow Diets

• Forages can supply 20 to 70% a mineral• Accuracy on mineral concentration in forages

more important – less error tolerance Cation – Anion balance Metabolic problems – greater risk with mineral

imbalance• Wet chemistry analysis recommended for

minerals in dry cow forages

DCAD, mEq/100g = [(%Na 43.5 + %K 25.6) (%Cl 28.2 + %S 62.5)]

LACTATING COWS CLOSE-UP DRY COWS

DCAD, mEq/100g = [(%Na 43.5 + %K 25.6) (%Cl 28.2 + %S

62.5)]

Macro Minerals in Forage Summary

• Forages are an important source of most macro minerals in lactating and dry cow rations.

• Ration formulation needs to consider– Requirements– Sources– Amounts fed – excess as well as deficiencies– Interactions amongst minerals fed in excess

Macro Minerals in Forage Summary

• NIRS acceptable estimator of Ca, P, K, Mg and S in lactating rations.– Formulations usually exceed minimum requirements

• Forages are a greater proportion of dry cow ration and mineral formulation requires accuracy – Wet Chemistry mineral analysis recommended.

• Precision feeding lactation and/or dry cow diets require wet chemistry analysis of minerals.

THANK YOU!