Macro-Minerals in Forages and Dairy Cow Requirements

Report
Forage Macro-Minerals
(Ca, P, K, Mg, Na, Cl, S)
and
Dairy Cow Requirements
Jim Linn, PhD
Professor Emeritus – University of Minnesota
Milk Specialties Global
Waconia Farm Supply
Importance of Minerals
Animal
Health
Production/Reproduction
Ration cost
Lactating Cow
Close-Up Dry Cow
8 to 10% of total
$/cow/day
0.75 - 1.00
18 – 22% of total
$/cow/day
0.75 - 1.00
Nutrient Composition (% DM)
of Dairy Rations
100
90
5.5
5.5
3.5
7.0
17
14
80
70
60
Minerals
Protein
28
36
NDF
NonFiber CHO
50
40
30
Fat
44
20
39
10
0
Lactating Cow
Close-up Dry Cow
Forage Minerals
Forage minerals
Contribute to animal requirement
Variability – species, maturity, soils, fertilization
Animal – 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 Minerals
Haylage 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
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
Source – Dairyland Labs, Arcadia WI
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 Minerals
SGS Forage Summary - 2012
Mineral
Legume
Haylage
Grass
Haylage
Grass 2+
Haylage
Mixed
Haylage
Mix-Leg
Haylage
Corn
Silage
------------------------------- Mean / SD ---------------------------------------------
Ca
SD
P
SD
K
SD
Mg
SD
1.13
0.67
0.75
1.05
1.33
0.22
0.37
0.26
0.25
0.39
0.34
0.07
0.29
0.31
0.32
0.29
0.30
0.21
0.07
0.08
0.07
.07
0.06
0.03
2.46
2.57
2.65
2.45
2.41
0.88
0.54
0.78
0.58
0.63
0.54
0.24
0.27
0.25
0.30
0.26
0.31
0.18
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
L
b
F
e
e
d
D
M
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
52 lb DM
17% CP
1.18 Mcal ME/lb
32% NDF
25.5% Starch
61 % Forage DM
Macro Minerals for Lactating Cows
Requirements 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, 2013
Sodium Buffers
b Higher forage concentrations - legume
a
Calcium Contribution From Feeds
Lactating cow diet – 0.90% Ca
45.0
40.0
35.0
30.0
25.0
lb 20.0
or
15.0
%
10.0
5.0
0.0
lb Feed DM
% Ca contribution
Phosphorus Contribution From Feeds
Lactating cow diet – 0.40% P
25.0
20.0
15.0
lb
or10.0
%
5.0
0.0
lb Feed DM
% P contribution
Magnesium Contribution From Feeds
Lactating cow diet – 0.35% Mg
40
35
30
25
lb 20
or 15
%
10
5
0
lb Feed DM
% Mg contribution
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 Feeds
Lactating cow diet – 1.5% K
60
50
40
lb 30
or
% 20
10
0
% K contribution
Sulfur Contribution From Feeds
Lactating cow diet – 0.28% S
35
30
25
20
lb
or 15
% 10
5
0
% S contribution
Sodium and Chloride Contribution From Feeds
Lactating cow diet – 0.5% Salt
60
50
40
lb 30
or
% 20
10
0
Ration – 0.5% Na and 0.62% Cl
Minerals in Rations of Close-up Dry Dairy Cows
Close-up Dry Cow Diet
28 lb DM/day
•
•
•
•
•
•
Grass hay
Corn silage
Corn
Protein
Macro minerals
TM/Additives
lb/cow/day
8.3
13.7
0.8
3.8
1.04
0.64
Close-up Dry Cow Diet
% Macro Mineral from Forage
Diet mineral %
Ca – 1.60
P – 0.38
Mg – 0.41
S – 0.36
Na – 0.09
Cl – 0.50
DCAD - +0.3
80
70
60
% 50
40
30
20
10
0
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)]
DCAD, mEq/100g =
[(%Na  43.5 + %K  25.6)  (%Cl  28.2 + %S  62.5)]
LACTATING COWS
CLOSE-UP DRY COWS
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!

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