Corn Silage Inoculants Review

1
Corn Silage Inoculants Review

• Gbola Adesogan
• Department of Animal Sciences
• IFAS, University of Florida

2
Outline

• Silage fermentation process
• Chemical additives
• Organic acid additives
• Ammonia (urea)
• Inoculants
• Definition
• Roles
• Types
• Effectiveness
• Take home messages

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Chemical changes during fermentation

• Anaerobic bacteria ferment sugars to volatile
  acids
• e.g. lactic, acetic butyric acids
• Acids pickle the forage and inhibit undesirable
  microbes
• Protein is partially degraded into ammonia
• These processes can cause DM losses (effluent /
  seepage)

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Chemical changes during fermentation

• Pickling / fermentation of the forage

Scale ()
20
15
10
5
1
21
Days
CROP
SILAGE
5
Fermentation pathways
Product
Nutrient Losses
Substrate (Microbe)
Fermentation
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Organic acids

• Role
• Rapidly reduce pH hence inhibit undesirable
  microbes
• Antifungal hence enhance aerobic stability
• Types
• Pure acids e.g. formic, propionic, acetic
  benzoic acids.
• Effective but caustic hazardous
• Buffered organic acids Ca Na salts of pure
  acids
• Less caustic safer to handle

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Ammonia (urea)

• Role
• Alkaline and antifungal in nature
• Improves aerobic stability
• Contributes CP
• Concerns
• Narrow harvest window
• If lt 60 moisture volatilization
• If gt70 moisture N loss in effluent
• May hinder fermentation increase DM losses
• V. caustic, protective clothing required
• Ammonia poisoning

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Inoculants

• DefinitionAdditives containing bacteria selected
  to grow quickly and dominate the bacterial
  population in the silage
• Types
• Traditional (homofermentative) inoculants
• e.g. Lactobacillus plantarum
• ? lactic acid ? pH, acetic butyric acids
• ? losses of DM (1-3), sugar and protein
• May increase fiber digestion animal performance
  (3-5)
• Newer inoculants (heterofermentative)
• Aerobic stability enhancers
• e.g. L. buchneri

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Effectiveness of inoculants
n 221
233
148
60
34
82
39
40
35
Positive trials
20
0
pH
Ammonia
DM loss
Lactic/Acetic
Bunk Life
DM digestibility
Fiber digestibility
(Muck Kung, 1997)
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Effectiveness of inoculants in different silages
Fermentation 60
Intake 28
Gain 53
Milk production 47
(Muck, 2002)
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Effectiveness of inoculants in different silages
60
40
trials with lower pH
20
0
Alfalfa
Grass
Corn
Sm. Grain
(Muck and Kung, 1997)
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Epiphytic bacteria on Standing Crops
(Andrieu Gouet, 1990)
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Contrasting views on inoculants

• Results from over 200 laboratory-scale silo
  studies, indicated bacterial inoculants were
  beneficial in over 90 of the trials. A
  good-quality, effective inoculant should be
  applied to every load of forage ensiled!
• (Bolsen, 1997)
• Reviewed corn silage inoculants articles for 5
  years
• We dont see enough benefits to recommend
  inoculants for corn silage (Muck, 2001)

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Forage factors affecting inoculant action

• Forage epiphytic microbial population
• Forage sugar content
• Forage buffering capacity
• Forage maturity stage
• Forage hybrid / variety

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Inoculant factors affecting inoculant action

• Bacteria strain and composition
• Bacteria viability
• Inoculant application rate
• gt 100,000 live bacteria (cfu)/g or gt 90 billion
  bacteria / ton
• Inoculant form
• Liquid inoculants act faster more evenly
  distributed
• Must use within 24h inactivated by chlorinated
  water
• All inoculants are not created equal

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Inoculants are most effective for corn silage for

• Fermentation enhancement when epiphytic bacteria
  are compromised -
• Immediately after frost
• Dry crop
• Immature crop
• Use traditional homofermentative inoculants
• Aerobic stability enhancement
• Homofermentative inoculants reduce acetate and
  propionate, hence are less effective
• Use L. buchneri (heterofermentative)

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QUESTIONDoes anyone know if I can re-bag corn
silage? We need more pavement and the bag is in
the way. Would it work better to put it in a
bunker silo?

• ANSWERS
• No problemo re-bagging. Would very much
  recommend it.
• We rebagged some corn silage two years ago and
  were left with a horrible pile of garbage.  The
  excellent corn silage had become inedible. Right
  now we're using it as part of our compost
  program.   

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Bunk /Aerobic spoilage

• More prevalent in corn small grain silages
• Can cause lt 50 of losses in silage DM
• Spoilage of the top 1m 500 to 2500 (Bolsen,
  1997)
• Causes
• Air entry into good silage
• Air pockets in poor silage
• Untidy silo faces
• Slow feedout
• Effects
• Reduce intake
• Reduce nutritive value
• Produce mycotoxins

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Effect of inoculants on aerobic stability of corn
silage (Ranjit Kung, 2000)
Inoculant Application rate (cfu/g) Acronym
Control 0 Control
Lactobacillus buchneri 100,000 LB Mod
Lactobacillus buchneri 1,000,000 LB High
Lactobacillus plantarum 1 1,000,000 LP 1
Lactobacillus plantarum 2 1,000,000 LP 2
Storage-mate NA Store-mate
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Effect of inoculants on composition
10
7.5
5
DM
2.5
0
21
Effect of inoculants on aerobic stability
gt900
Aerobic stability (hours)
38
36
33
32.8
27
LP-2
LP -1
Store- mate
Control
LB x Mod
LB x High
(Ranjit Kung, 2000)
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L. Buchneri Summary

• Benefits
• Enhanced aerobic stability
• No adverse effects on intake (observed so far)
• Limitations
• More nutrient losses than homofermentative
  inoculants
• Future work
• Combining front (homofermentative) back end
  (heterofermentative) inoculants

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Silage Additive Regulators

• Countries with pre-market screening of additives
• UK UKASTA ?
• Canada Ag. Canada ?
• USA None ?

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Take Home Messages

• Only use inoculants with
• Independent research-attested track record
• gt90 billion live bacteria / ton
• L. plantarum for fermentation enhancement
• L. buchneri for bunk life enhancement
• Dont choose by cost (35 cents to 1 per ton)
• Use only corn silage inoculants for corn silage
• Apply at chopper, not into wagon or at bunker
• Store in a cool, dry place
• Once diluted, use within 24 h.

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Silage producers have long recognized the
positive effects of using an inoculant to insure
the proper transformation of forage into a
palatable and digestible feedstuff
Recent quote

• Beware, inoculants are useful but they are
  neither
• A substitute for bad management
• magic potions

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Take Home Messages

• Harvest promptly (35DM or 1/3-2/3 milk line)

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Take Home Messages

• Fill bunker promptly
• Pack, pack and pack again
• Seal immediately properly tires

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Take Home Messages

• Manage the silo face
• Feedout quickly (6 inches/day)
• The narrower the bunker, the better
• Minimal disturbance
• Heat loss production volatilized

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Grass silage protein fractions
Silage
Grass
120
100
ammonia
80
nitrate
amines
60
peptides
Nucleic acids
Free amino acids
40
True Protein
20
(Jones, 99)
0
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Effect of delayed sealing on fermentation (Uriate
et al., 2001)
Day Control Control Additive-treated Additive-treated
Control Immediate seal Delayed (48h) seal 0h seal Delayed (48h) seal
pH at opening 3.7 3.7 3.5 3.6
pH 4 days later 3.6 8.0 3.7 8.2
Lactic acid at opening ( DM) 4.5 4.9 4.1 4.5
Lactic acid 4 days later 4.4 0.3 3.9 1.5
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Effect of delayed sealing on stability yeasts
(Uriate et al., 2001)
Day Control Control Additive-treated Additive-treated
Control Immediate seal Delayed (48h) seal 0h seal Delayed (48h) seal
Lactate utilizing Yeasts at opening 4.9 5.7 5.0 5.5
Lactate utilizing Yeasts 4 days later 8.2 9.4 9.0 8.7

Aerobic stability (hours) 113 65 137 89
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Ensiling losses-
Source Net Energy lost
Respiration 1-2
Wilting 2-5
Heterofermentative bacteria 4
Secondary Fermentation 0-5
Effluent 5-7
Aerobic spoilage in the silo 0-10
Aerobic spoilage at feedout 0-15
(McDonalds et al., 1991)
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How does buchneri work

• Uses heterolactic fermentation
• More acetate produced
• Acetate is an anti-fungal agent
• Inhibits-spoilage causing yeasts moulds
• Disadvantages of heterolactic fermentation
• Depressed lactate production higher nutrient
  losses
• Depression in intake if excess acetate is
  produced

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Chemical composition of corn silage
Composition
pH 3.7 4.2
Lactic acid () 4 - 7
Acetic acid () 1 - 3
Propionic acid () lt0.1
Butyric acid () lt0.1
Ethanol () 1 -3
Ammonia N ( of total N) 5 - 7
(Kung, 2002)
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Effect of temperature on corn silage pH
37OC
Target pH
28OC
(Weinberg et al., 2001)
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Effect of temperature on corn silage pH
Inoc, 41OC
Inoc, 24OC
Control 24OC
(Weinberg et al., 2001)
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Temperature matters!

• Inoculated silages may spoil more than respective
  control silages at high temperatures which
  inhibit the growth of inoculant bacteria.
• Special care should be taken during silage making
  and unloading in warm climates
• Florida corn silage producers must do better than
  average.

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Fermentation vs. stability

• Traditional view
• Conventional inoculants (homofermentative)
  enhance fermentation but often reduce bunk life
• Cause Reduced acetic propionic acid
• Emerging view
• L. buchneri (heterofermentative) inoculants can
  improve bunk life