the final step: covering the bunker

Stepping Forward December 9 & 10 | Dairy Summit 2015 | Baraboo, Wis.

The Final Step: Covering the Bunker

Michelle Windle, PhD Forage Products and Dairy Technical Service Specialist


Topics • Fermentation 101

• Spoilage: A brief overview

• Silo covers – Plastic and beyond

• Preventing spoilage from happening


Silage Microbiology 101 • In the field, plants are covered in microorganisms. Per gram:

• Microorganisms have ideal environments for growth – Some need oxygen; some need a lack of oxygen

– Some need a low pH; some need a high pH

– Typically, the “bad guys” like a high pH and lots of oxygen

– Therefore, the goal of ensiling: a low pH and no oxygen

Aerobic bacteria >10,000,000

Lactic acid bacteria ~1,000,000

Enterobacteria ~1,000,000

Yeasts ~100,000

Molds ~10,000

Clostridia ~10,000


Aerobic Phase

Up-Front Fermentation

Storage Feedout

Phases of Ensiling:

Aerobic Aerobic

Begins once silage is exposed to oxygen;

Also known as “spoilage”

• Crop is still respiring, using sugars and proteins

• Aerobic bacteria are alive and well, and they use sugars and protein; produce heat

• Fermentation cannot begin until oxygen is gone

Begins once the silo is covered and oxygen is gone;

Continues so long as oxygen is absent

Oxygen

Anaerobic

pH acids


How does the initial aerobic phase affect feedout stability?

Prolonged aerobic phase

Less sugars for

fermentation

Less acetic acid;

Higher silage pH

More yeast More

spoilage


What does spoilage look like?


How spoilage occurs: A “Domino Effect”

Silage is exposed to air

Oxygen wakes yeasts up; they grow in numbers and degrade lactic acid raising pH

Highly degradable nutrients ($) are destroyed; loss of DM ($)

Heat is produced

The increase in pH “wakes up” molds/bacteria, causing massive spoilage


Spoilage changes the nutrient profile of feeds

Item Fresh TMR Spoiling TMR

pH 4.16 5.17

WSC (Sugars), % 2.46 1.85

Lactic acid, % 4.17 2.59

Acetic acid, % 0.97 0.64

Ethanol, % 5.82 6.07

Yeasts, cfu/g 107,151 66,069,345

2013 Windle and Kung


Summary of Negative Effects of Spoilage • DM losses

• Heated feed

• Nutrient losses

• Decreased digestibility

• Decreased feed quality/value

• Decreased palatability and intake

• Reproductive problems

• Sick animals (potential for toxins)

• Reduced milk production

• Lost money!


How to avoid spoilage: A cheat sheet

• Harvest at the proper moisture level

• Pack to achieve optimum density

• Cover promptly, with good quality plastic

• Manage the silo


How does moisture at harvest affect spoilage almost a year later, during feedout?

• Porosity: A measure of the air spaces

• A lower number (<0.40) is good

• Porosity increases…

– As density decreases

– As DM content of the crop increases


What is the ideal moisture content?

Crop DM Content Moisture Content

Corn Silage 32 – 35% 65 – 68%

Snaplage 58 – 64% 36 – 42%

High-Moisture Corn 64 – 72% 28 – 36%

Haylage 40 – 45% 55 – 60%

Baleage 45 – 55% 45 – 55%

Ryelage/Wheatlage 35 – 40% 60 – 65%

Note that these are dependent on the silo structure – For example, horizontal bag silos are typically drier than bunkers






• Manage the silo


• Pack tightly

• 6-8 inch layers

• Heavy tractors

• Keep tractor on the pile

Packing well excludes oxygen and jump-starts fermentation

Pack tractor wt ÷ 800 = tons/hr


Not enough weight!






• Manage the silo


Silos that are not promptly sealed….

• Have less silage in them once opened (poor DM recovery due to prolonged aerobic phase and inefficient fermentation)

• Have less sugars for fermentation

• Have a higher pH – More prone to Clostridia

• Have less total acids produced

– Silage acids are healthy! – Lactic acid has great DM recovery – Acetic acid prevents spoilage

• Have more spoilage yeasts

• Are more prone to spoilage upon opening


Silo Covers: What’s out there? • Plastic covers

– Standard Polyethylene (PE) – Oxygen barrier – Two-in-one

• One-step • Reinforced one-step • Both bonded together • Both rolled together

• Reusable tarps

• Edible covers


Polyethylene plastic: Background

• Use of black and white (PE) plastic probably originated in Europe as repurposed fumigation plastic

• Tires help to exclude oxygen and prevent it from spreading if there is a hole


What have we learned?

• Thicker is better (especially on baleage) – Less oxygen permeability

– More puncture resistant

• Color matters for UV purposes

• Oxygen-barrier technology is useful and worth the extra work – Oxygen barrier plastics have an additive – polyamide/EVOH

– Less oxygen gets through the plastic


0

5

10

15

20

Control Treated

%

DM Losses in Bunker Silos

0

2

4

6

8

10

Control Treated

%

DM Losses in Balage

02

4

68

10

12

Control Treated

%

Inedible Silage

0

50

100

Control Treated

ho

urs

Aerobic Stability

Oxygen barrier plastics: Meta analysis of 51 trials (Wilkinson and Fenlon, 2013)

B+W B+W with OB

B+W B+W with OB

B+W B+W with OB

B+W B+W with OB


Black and White Plastic with OB properties • Pros:

– Saves labor

– Thicker plastic

– May be reinforced with cross-hatching fibers

– Oxygen barrier

• Cons: – May be pricey

– May lack the “cling” factor that eradicates oxygen quickly

– May flap in the wind during feedout if face isn’t managed properly


Two-in-One Covers • May be physically connected, or simply

rolled together

• Appeal: Convenience

• If connected, do they actually separate?

• Research?

• Quality of the “oxygen barrier” film?


Not All “Oxygen Barrier” Plastics are Equal

23.2 84 154 545 650

2691

4039 4146 4304

6388

8303 8769

0

2000

4000

6000

8000

10000

OTR

, cc/

m2

/day


SiloStop (23 cc/m2/d)

KSI (154 cc/m2/d)

Plastic Comparison

Polydress (8769 cc/m2/d)

HiTec (8303 cc/m2/d) Clear Up North (6388 cc/m2/d)


Reusable tarps

• Woven or nonwoven

• Pros – Less waste – No tires (may be less labor) – Stronger than plastic, protecting

against animals/weather – Can save money

• Cons – Pricey up-front investment – In winter, can be a challenge – People may cut/ruin them

www.farmshow.com

www.securecovers.co.uk


Edible coverings

• Plastic covers are: – Convenient and effective

– Wasteful: Non-biodegradable plastics (including silo plastics) make up as much as 30% of municipal solid waste in the US

– Labor-intensive

– Expensive

• Edible covers may alleviate all of this; may bond to forage particles making tighter seal


Edible silo covers

• What are they made of? – Starch/salt mixture, covered with a thin layer of molten paraffin wax

– Fat

– Peanut butter

– Apple pulp

– Molasses

– Small grains

– Sod

– Sawdust

– Chopped Straw

– Composted manure solids

– Zein proteins


Reality of edible covers • Labor intensive (need to mix the components, heat them while

mixing, etc.)

• New equipment required (i.e. a commercial concrete pump)

• May require ingredients to be held/applied at high temperatures

• Uneven application

• Edible cover may be edible by pests, too (vermin and/or bacteria)

• Cost

• Ingredients may not be good for the rumen (i.e. unsaturated fats)

• Ingredients may take up room in the diet

• How resistant is it REALLY? – Weight of snow

– Slow drizzle over days may degrade it

– May get brittle in the cold and crack, letting oxygen in






• Manage the silo


Bagging tips

Check bags and covers regularly for holes

Kung, 2004


Face Management

• Keep face clean

• Knock down only enough silage to feed in a day

• Remove more for drier and poorly packed silages to stay ahead of spoilage


• Minimum 6”/d in winter and 12”/d in summer

• Recommended feedout rates for bag silos:

Feed Out at the Proper Rate

Bag Size Winter Rates (ft/d) Summer Rates (ft/d)

8’ 1 2

9’ 1 2.25

10’ 2 2.5

11’ 2.25 2.75

12’ 2.5 3

Ag Bag recommendations


Additives to help with spoilage:

• Managing already spoiled silage – Dilution (but this may decrease feedout rate and

exacerbate the problem)

– Probiotics/Yeasts?

– Binders?

• Prevention is the best route – After ensiling: Acids

– Before ensiling: Inoculants


It’s More Efficient to Treat at Ensiling Then at the Wagon

0

50

100

150

200

250

300

350

400

CS TMR

Hours of Stability

Ctrl LB TMR mate 5 lb/t TMR mate 10 lb/t

Added to TMR

Schmidt and Kung 2006


Recommendations from Limin Kung:

Should We Inoculate All Silages with L. buchneri?

No!

When is L. buchneri Most Useful?

• Silages with high starch:

HM corn, corn silage, cereal

grain silages

• Poor bunk life, heating TMR

issues

• Silages with slow feed-out

rates/big faces

• Silages with multiple faces

• Drier silages

• Silage that will be moved

• Summer feed

• Prolonged storage

• Silages that are poorly

packed

• Any silage with oxygen

challenges


In Summary, The Ideal Silo….


0

5

10

15

20

25

10 13 15 16 17 20

Is packed well… D

M lo

ss, %

Packing Density Lb/cu ft. (Ruppel, 1992)


Uses stretch

marks to help

with packing…


Has only one face…


Manages the plastic during feedout

• Keep the face down on the leading edge


Fits the Structure…


Can be driven over from all

directions


Summary

• Spoilage is best measured/identified by yeast counts and temperature

• To prevent spoilage, focus on – Limiting oxygen – Limiting yeast growth – Management – Using the best inoculant


Thank you!

the final step: covering the bunker

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