U.S. Dairy Forage Research Center, USDA Agricultural Research Service

United States Department of Agriculture

Harvesting and Storing Dry Hay:

Cautions and Consequences

Alfalfa and Forage Workshop

March 28, 2018

Maricopa, AZ

Wayne Coblentz

USDA-ARS

US Dairy Forage Research Center

Marshfield, WI

≠

Experimental (Weather) Conditions in Arizona Can’t Be

Duplicated in Wisconsin!

Outline/Objectives

TOPICS

1. Rain Damage

2. Spontaneous Heating/Forage Quality

3. Preservatives

?Rain Damage

0

2

4

6

8

10

12

0.5 1.0 1.5 2.0 2.5 3.0

DM

Lo

ss

(%

)

Simulated Rainfall (inches)

76.1% (Q = 0.01)

40.0% (L = 0.01)

13.0% (Q < 0.01)

Scarbrough et al., 2005

0

2

4

6

8

10

12

0.5 1.0 1.5 2.0 2.5 3.0

DM

Lo

ss (

%)

Simulated Rainfall (inches)

67.4% (L = 0.01)

15.3% (Qu = 0.01)

4.1% (C = 0.03)

Dry Matter Losses

8

Orchardgrass

Bermudagrass

Effects of Natural Rainfall1,2,3 on Alfalfa for Silage

Coblentz and Muck, 2012

1 Initial Moisture, ~80%; Final Moisture, ~55%2 Moderate Rainfall, 1.1 inches (total exposure = 47 to 52 hours)3 Severe Rainfall, 1.9 inches (total exposure = 189 to 191 hours)

Work with Tall Fescue -

Effects of Rainfall on

Voluntary Intake by Steers

Treatment Bale

Moisture Rainfall Events

Rainfall MAX1

% no. inches oF

High Moisture (HM) 22.5 0 0 122

Low Moisture (LM) 9.9 0 0 109

H-Rain (HM-R) 24.6 1 0.9 123

L-Rain (LM-R) 9.3 3 2.9 89

Anim. Feed Sci. Technol. 109: 47-63 (2003)

1 Maximum internal bale temperature within small rectangular bales.

65

70

75

80

HM LM HM-Rain LM-Rain

Before Storage

After Storage

Neutral Detergent Fiber (%)

Anim. Feed Sci. Technol. 109:47-63 (2003)

Voluntary Intake (% of BW)

Anim. Feed Sci. Technol. 116:15-33 (2004)

Effects of Natural Rainfall, and Spontaneous Heating on

NDF and Voluntary Intake of Tall Fescue Hay by Steers

Hay producers in humid environments constantly must choose between

subjecting their valuable hay crops to rain damage, or accepting

inadequate desiccation and spontaneous heating.

Characteristics of Spontaneous Heating

• initially, result of plant and microbial respiration (plant sugars → CO2, H2O, and heat)

• occurs in consistent patterns across forages

• many contributing factors

• moisture**

• bale density and/or size

• environmental factors

• storage site

• preservatives

• Measures of heating are very good predictors of (negative) changes in forage quality!

Traditionally, hay research has been conducted with 80-lb rectangular hay bales that are relatively easy to replicate.

Y = 56.3 x - 891r² = 0.902

0

200

400

600

800

1000

1200

1400

15 20 25 30 35 40

He

ati

ng

De

gre

e D

ays

> 8

6oF

Moisture at Baling (%)

conventional 80-lb bales

Alfalfa

Bermudagrass

Coblentz et al. (2000)

Coblentz et al. (1994)

conventional 80-lb bales

Source: Oklahoma State University

DM Recovery vs.

Spontaneous Heating

plant sugars → CO2, water, and heat

(Various Sources)

Wisconsin Round-Bale Studies

• alfalfa-orchardgrass hays from 3 harvests

• 3 bales/interactive treatment (3, 4, or 5-ft diameter)

• moisture ranged from about 10 to 45%

• storage was outdoors on wooden pallets

• bale temperatures monitored daily

• rigorous sampling on a pre- and post-storage basis

Maximum Internal Bale Temperature vs.

Initial Bale Moisture

Coblentz and Hoffman (2009)

4-ft bales

Y = 1.5x + 91.5

r2 = 0.943

3-ft bales

Y = 1.6x + 86.2

r2 = 0.955

5-ft bales

Y = 1.9x + 87.1

r2 = 0.971

100

110

120

130

140

150

160

170

180

5 10 15 20 25 30 35 40 45 50

Bale Moisture, %

Ma

xim

um

Ba

le T

em

pe

ratu

re,o

F

Coblentz and Hoffman (2009)Source: Oklahoma State University

Coblentz et al. (2010)

Crude Protein (CP)

N = 32 baling treatments

Mean = 1.0 ± 0.67 percentage units

Initial = 18.1%, which corresponds generally to

∆CP = 0 on the y-axis

NDF

N = 32 baling treatments

Initial = 46.5%, which

corresponds generally to

∆NDF = 0 on the y-axis

Wisconsin Round Bale Study (2006-07)

-1.0

1.0

3.0

5.0

7.0

9.0

11.0

0 600 1200 1800 2400 3000 3600

∆N

DF,

Pe

rce

nta

ge

Un

its

of

DM

Heating Degree Days > 86oFCoblentz and Hoffman, 2009

Van Soest, 1982

Bermudagrass Hay (Small Square Bales)

(Coblentz et al., 2000)

Heat Damaged Protein (ADICP)

-2.0

0.0

2.0

4.0

6.0

0 400 800 1200 1600 2000

Heating Degree Days > 30oC

ΔH

EM

I, P

erc

en

tag

e U

nit

s

■ Y = (0.000030x2) + 1.8

R2 = 0.801

● Y = 187.3*(1/√x) - 4.6

R2 = 0.733

Wisconsin Round

Bale Study (2006-07)

Hemicellulose

N = 32 baling treatments

Initial = 15.1%, which

corresponds generally to ∆HEMI

= 0 on the y-axis

Intersection of regression lines

occurred at 347 HDD > 30oC

-2.0

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

0 400 800 1200 1600 2000

Heating Degree Days > 30oC

ΔH

EM

I o

r Δ

AD

ICP

, P

erc

en

tag

e U

nit

s o

f D

M o

r C

P

(●) ADICP

Y = 14.9 – (15.7 * (e- 0.0000019*x*x

))

R2 = 0.934

Acid Detergent Insoluble Crude

Protein (ADICP)

N = 32 baling treatments

Initial = 6.3% of CP and 15.1% of

DM, which correspond generally

to ∆ADICP = 0 and

∆Hemicellulose (gray line) = 0,

respectively, on the y-axis

Coblentz and Hoffman, 2009

Coblentz et al. (2010)

Effects of Heating on

Digestibility of

Alfalfa/Orchardgrass Hays

Coblentz and Hoffman, 2009

Coblentz and Hoffman, 2009

● Charred Areas

Internally

TDN

N = 32 baling treatments

Initial = 57.9%, which corresponds generally

to ∆TDN = 0 on the y-axis

-13.0

-11.0

-9.0

-7.0

-5.0

-3.0

-1.0

1.0

3.0

0 600 1200 1800 2400 3000 3600

ΔT

DN

, P

erc

en

tag

e U

nit

s o

f T

DN

Heating Degree Days > 86oFCoblentz and Hoffman, 2010

Most Energy Losses Are Associated With

Respiratory Losses Of Sugars

Coblentz and Hoffman, 2010

Use of Propionic Acid-Based Preservatives:

A Success Story

≠

A Word of Caution

Research almost always is conducted on

individual bales, or on very small stacks –

please interpret results accordingly!

Source: Oklahoma State University

Summary of 10 Experiments

Rotz et al. (1991)

• each experiment contained:

- small rectangular bales

- positive (dry) hay control (10 to 20%)

- treated hays (20 to 37%)

- untreated hays (19 to 40%)

• application rates ranged from 1.0 to 2.3% of

bale weight (50% dilution)

• some experiments contained more than one

treated vs. untreated comparison

Conclusions

• results were inconsistent across studies

• spontaneous heating was reduced, but not

eliminated within treated hays

• regardless of treatment, HDD > 86oF were

positively related to initial bale moisture

• losses of DM were positively related to HDD

> 86oF accumulated during the first 30 to 45

days of storage

Group Moisture Volume

Wet

Weight

Dry

Weight

DM

Density

% ft3 lbs lbs lbs DM/ft3

High 27.4 40.7 644 467 11.5

Medium 23.8 40.7 626 476 11.8

Low 19.6 42.1 613 494 11.7

SEM 0.80 0.39 9.3 10.4 0.20

Application of Propionic Acid Preservative1 to Large Square

Bales2 of Alfalfa-Orchardgrass Hay

1 Rates: 0, 0.6, or 1.0% of fresh weight.

2 Large square bales were 3 x 3 x 6 ft.

Coblentz et al. (2013)

Coblentz et al. (2013)

0

100

200

300

400

500

600

700

800

HD

D >

86

oF

High (27.4%) Medium (23.8%) Low (19.6%)

Moisture, %

1.0% 0.6% 0%

80

90

100

110

120

130M

ax

imu

m T

em

pe

ratu

re,

oF

High (27.4%) Medium (23.8%) Low (19.6%)

Moisture, %

1.0% 0.6% 0%

Effects of a Propionic-Acid-

Based Preservative on

Heating Characteristics of

Large-Square Bales of

Alfalfa Hay

N = 9 baling treatments

Prestorage NDF = 53.7%, which

corresponds generally to ∆TDN = 0 on

the y-axis

Coblentz et al. (2013)

55

57

59

61

63

65N

DF

, %

High (27.4%) Medium (23.8%) Low (19.6%)

Moisture, %

1.0% 0.6% 0%

45

47

49

51

53

55

TD

N,

% o

f D

M

High (27.4%) Medium (23.8%) Low (19.6%)

Moisture, %

1.0% 0.6% 0%

N = 9 baling treatments

Prestorage TDN = 55.3%, which

corresponds generally to ∆TDN = 0 on the

y-axis

Use of Propionic Acid Preservative on Round Bales of

Alfalfa Hay: A No Success Story

Bale Diameter = 5 ft.

Bale Weight = ~ 1200 lbs

Coblentz and Bertram (2012)

Maximum Internal Bale Temperature vs. Bale Moisture for

Large-Round Bales of Alfalfa Hay Treated with a Propionic-

Acid Preservative

Coblentz and Bertram (2012)

Propionic Acid on Round

Bales of Alfalfa Hay

Heating Degree Days > 86oF

vs. Initial Bale Moisture

0

500

1000

1500

2000

2500

10 15 20 25 30 35 40

Hea

tin

g D

eg

ree

Days

> 8

6oF

Initial Bale Moisture, %

0

1000

2000

3000

4000

5000

6000

7000

10 20 30 40

Hea

tin

g D

eg

ree

Days

> 8

6oF

Initial Bale Moisture, %

○ Untreated ● Treated (0.5% of wet weight)

First 28 Days

Entire Storage

Period

○ Untreated ● Treated (0.5% of wet weight)

Coblentz and Bertram (2012)

Pre-storage Concentrations:

ADICP = 6.9% of CP

TDN = 61.2%,

which correspond generally to

∆NDF, ∆ADICP, and ∆TDN = 0 on

the y-axis

Coblentz and Bertram (2012)

So Why Were Responses Different?

● Some of this discrepancy might be explained by application strategy/system.

● Is bale size a significant factor?

● During 2016, we initiated a long-term project1 assessing the effect of bale size

(round-bale diameter) on the effectiveness of propionic-acid-based preservatives

applied with the Harvest Tec 647C application system.

1 Project funded in part by the generosity of the Midwest Forage Association

Interaction of Bale Size and Acid Application Strategy 1

---------- Moisture ----------

Treatment Diameter Lab

Mean

Baler

High

Baler

Acid

Rate

Baling

Time

Baling

Rate

Wet

Weight

Dry

Weight

DM

Density

-------------- % --------------- % sec tons/hr lbs lbs DM lbs DM/ft3

Control 4 21.5 20.0 23.0 0 58 20.6 654 514 9.9

Fully

Automated

4 20.0 23.0 25.7 0.60 61 19.8 666 533 10.0

Constant

Bale Rate

4 18.7 19.3 22.7 0.29 64 18.8 661 538 10.3

Control 5 21.4 21.0 29.0 0 117 14.7 926 728 10.5

Full

Automated

5 20.5 22.0 26.0 0.51 87 19.3 923 735 10.5

Constant

Bale Rate

5 21.6 24.0 28.7 0.60 91 18.6 932 731 10.3

SEM 1.05 1.88 1.65 0.058 6.7 1.07 8.3 11.5 0.26

1 Project funded in part by the generosity of the Midwest Forage Association

Maximum Bale Temperature and HDD > 86oF

341 Project funded in part by the generosity of the Midwest Forage Association

Concentrations of NDF, 48-Hour

NDFD, and TDN after a 75-Day

Storage Period

Project funded in part by the generosity

of the Midwest Forage Association

Three Field Replications of 5-ft Bales

● Control

● Fully Automated

● Constant Bale Rate

Replication 1 Replication 2

Replication 3

Project funded in part by the generosity

of the Midwest Forage Association

Summary

● As hay packages become larger, the risk of spontaneous heating

increases, and the target bale moisture for satisfactory storage

becomes drier.

● Dry matter losses and negative changes in forage quality are closely

and directly associated with spontaneous heating.

● Propionic acid-based preservatives will not completely eliminate

spontaneous heating, and their effectiveness will decline as bale

moisture increases.

● When preservatives are ineffective, they will likely reduce maximum

bale temperature, but may prolong less-intense heating, possibly due

to retention of moisture.

● It should never be assumed that propionic-acid preservatives will be

as effective within large stacks of bales as they are within individual

bales!

Q U E S T I O N S ?

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