forage fermentation: how to make good silage
DESCRIPTION
Dr. Limin Kung of the University of Delaware presented this information for DAIReXNET on February 17, 2014. The recorded webinar can be found at http://www.extension.org/pages/15830/archived-dairy-cattle-webinars#.UwPQJc4gvZc.TRANSCRIPT
Forage Fermentation: How to Make Good Silage
Limin Kung, Jr.Dairy Nutrition & Silage Fermentation Lab
Definition of a high quality silage/forage
Nutrient recovery High nutritive
concentration (CP, starch, etc.)
High digestibility
by rumen microbes
Poor quality forage from field->Poor harvest and silo management ->
= Poor quality silage at feedingPoor quality forage at harvest ->
Excellent harvest and silo management ->= Poor quality silage at feeding
High quality forage at harvest ->Poor harvest and silo management ->
= Poor quality silage at feedingHigh quality forage at harvest ->
Excellent harvest and silo management ->= Excellent quality silage at feeding
Harvest Quality and Silo Management Have Profound Effects on Silage Quality at Feeding
Kung, 2001
Value of Potential Forage Loss in the Silo –$35/t for Corn Silage
----- DM Losses-----Tons of Silage/yr <10% 15% 20%
1,000 3,500 5,250 7,000
2,000 7,000 10,500 14,000
3,000 10,500 15,750 21,000
Good Poor Management
Expect losses in milk production and/or greater concentrate costs when feeding poorer silage
L. Kung, Jr., University of Delaware
Challenges with Alfalfa Silage High buffering capacity -> slow fermentation Difficult to wilt quickly Easily goes clostridial when DM is low (<30%) Substrate for fermentation can be limiting during
cloudy weather, heavy rains, prolonged wilts Difficult to pack when dry Easily heat damaged at higher DM (>50%)
L. Kung, Jr., University of Delaware
Help with Alfalfa Silage
Minimize wilting time (wide swath?) Maximize dry down hours during daylight Wilt to at least 35% DM Avoid excessive DM (not more than 50% DM) Avoid being rained on Avoid mowing and harvest under cloudy
conditions
L. Kung, Jr., University of Delaware
Consequences of Extreme DM on Alfalfa and Grass Silages
Too Wet (<30%) Too Dry (>45-50%)
-Clostridia -Tough to pack
protein degradation -Poor stability
DM/energy loss -Heat damage CP
low digestibility leading to low
butyric acid/amines digestibility
-SeepageL. Kung, Jr., University of Delaware
Consequences of Harvesting Corn for Silage at Extreme DMs
Too Early Optimum Too Late
(<28-30% DM) (>40% DM)
Low [starch] Low starch digestion
Low [energy] 32-36% DM Low acid production
Excess [acid] Tough to pack
High acetic acid Poor aerobic stability
Seepage
L. Kung, Jr., University of Delaware
Optimum Harvest Time for Corn Silage
~32 to 36% whole plant DMGood starch content and digestibility
Good fiber digestionGood packing in the silo
L. Kung, Jr., University of Delaware
Effect of Corn Silage Maturity on Starch Digestion in the Total Tract
adopted from Shaver, 2002
65
70
75
80
85
90
95
100
3031
.232
.433
.634
.8 3637
.238
.439
.640
.8 4243
.244
.445
.646
.8 48
Dry Matter %
Sta
rch d
ig. %
Unprocessed
*Based on data of Bal et al., 2000; Dhiman et al., 2000; Rojas-Bourrillon et al.1987
30 35 40 45 Whole Plant Corn DM%
100
90
80
70
% StarchDigestion
½ milk line black layer
Set Chop Length at Harvest!!
Item C. Silage* Processed**
Top 3-8% 5-15%
Middle 45-65 >50
Lower 20-30 <30
Pan <5 <5
*Heinrichs, PSU **Hutjens, UI
Processing for Corn Silage
Cracks the kernel open to expose starch -> + digestion
Reduces TMR sorting
Improves silage packing
L. Kung, Jr., University of Delaware
Fecal Starch and Digestibility
(Ferguson, 2006)
Goal is to have less than 3-4% fecal starch1%-unit decrease in fecal starch ~ 1 pound more milk
Range in starch: 2.3 – 22.4%
Corn Silage Processing Score
% of starch passing through a coarse screen
(>4.75 mm)
Processing Rank
Greater than 70% Optimum
70% to 50% Average
Less than 50% Inadequately processed
Mertens, 2003
4.75 mm is 1/5 of an inch
Thumb Rules for Assessing the Degree of Processing
> 95% of kernels cracked (70% equal to or smaller than 1/3 to ¼ kernel size)
Nicking and crushing are not enough
Cob should be broken to >8 pieces These pieces would
Not pass through a 4.75 mm hole….
Thus, they are not processed enough!
4.75 mm diameter hole
L. Kung, Jr., University of Delaware
Separate Kernels from Forage in a Bucket of Water to Assess Kernel Processing
Kung, 2001
Post Processor?
L. Kung, Jr., University of Delaware
The Goals of Making Silage
Rapid preservation for maximum recovery of nutrients
Continued preservation of nutrients and excellent “shelf life”
Front-end
Back-end
Microbes at work in silage – silage making is like a war – good bugs must win!
“Good bugs” Lactic acid bacteria
heterofermentative homofermentative “Bad bugs”
Yeasts Molds Clostridia EnterobacteriaKung, 2001
Ideal Fermentation and Good Storage Conditions
sugars
lactic acid
pH
Days of Ensiling
acetic acid
No AirStable, high quality
No Air
Kung, 2001
Front end fermentation Back end storage
> 45 C
35 C
However… A good front end fermentation does not
automatically lead to stability during storage and feed out (backend)
A high concentration of lactic acid and/or low pH alone does not automatically equate to a stabile if silage is exposed to air
Ideal Fermentation but Poor Storage Conditions
sugars
lactic acid
pH
Days of Ensiling
acetic acid
No air
Kung, 2001
Front end fermentation Back end storage
Exposure to Air
>120 F
105 F
The “Domino Effect” From Air on Aerobic Spoilage – Bad BugsSilage is exposed to air
Yeasts ‘wake up’ and degrade lactic acid
Numbers of yeasts increase
Highly degradable nutrients are destroyed
Heat is produced
pH increases
Molds/bacteria ‘wake up’ causing further spoilage
More heating
Massive spoilageL. Kung, Jr., University of Delaware
The Negative Relationship Between Number of Yeasts and Aerobic Stability
0
40
80
120
160
200
1000 10000 100000 1000000
Yeast, cfu/g
HoursOf
StabilityBefore
Spoilage
o
oo
o
o
oo
o
o
o
oo
o
o
o
Kung, University of Delaware
Changes in DMI When Heifers are Fed Aerobically Spoiling Feed
a
b
Der Bedrosian et al., 2012
107,151 yeast/g
Undesirable Clostridial Fermentation
sugars
lactic acid
pH
Days of Ensiling
Poor quality forageHigh NH3 and butyric acid
butyric acid
Forage too wetLow sugarsClostridia
>120 F
105 F
Front end fermentation Back end storage
acetic acid
•Fill quickly
•Pack tightly
•14-16 lb DM/ft3 CS
(225-260 kg DM/m3)
•15-17 lb DM/ft3 AS
(240-270 kg DM/m3)
•6-8 inch (15-20 cm) layers
•Heavy tractors
Silo Filling
Plastic on the Sidewalls
Greenfield, 2003
Cover With Plastic and Tires Immediately
White plastic better than black
6 is better than 4 mil Small bunks – consider 2
layers? (thin layer on bottom is best)
More weight on seams/edges
L. Kung, Jr., University of Delaware
Oxygen Barrier Plastics
Kung and McDonell, 2005
No Chia-Pet Covers!!!
Kung, 2007
Check the teeth on your baggersSharp teeth = -faster and tighter bagging-cleaner cuts on forage (less juicing)
L. Kung, Jr., University of Delaware
Keep Plastic Down at the Feeding Face
Kung, 2006 Kung, 2006
Face Management - Remove a minimum ??? inch/d- Remove more in hot weather and for
drier/poorly packed silages- Keep face clean, minimize face damage- Knock down only enough silage to feed
Face Shavers
(+) Most useful when density is low and/or feed rate is slow
May save 3% in DM
Savings in animal performance?
(-) Longer feeding time
“The Management Disconnect”This farm was so happy that they were using a face shaver!
L. Kung, Jr., University of Delaware
Microbial Inoculants Can Improve Silage Fermentation and Aerobic Stability
Help at the Front – Homolactic acid bacteria Faster fermentation Reduce clostridia Improved DM/energy recovery
Help at the Back – Lactobacillus buchneri Improved aerobic stability Fresher feed Less spoiling
Dual purpose – Combination of the above
Approaches For Using Silage Inoculants – Tools For Maintaining Good Fermentations
1. Preventing a clostridial fermentation- wet alfalfa and grasses- quick attainment of a low pH- conventional homolactic acid bacteria
2. Improving aerobic stability- HMC and corn silages- L. buchneri products
3. Making a good fermentation better - improvements in DM recovery
Modified from Muck 2008
General Inoculant Recommendations
By crop Alfalfa and grasss -> Ho* (>40% DM -> LbC**) Corn silage -> Ho or LbC (if aerobic challenges) HMC -> LbC
By DM < 30% DM -> Ho (avoid LB) > 40% DM -> LbC
*Ho = homolactic acid bacteria based additive
**LbC = L. buchneri + homolactic acid bacteria
Managing Your Inoculants Calibrate applicators frequently Optimize distribution Liquid applied is better in drier (>40% DM)
forages Do not mix inoculants with hot water Keep water temp in tanks < 95-100 F
Numbers of Viable Bacteria Were Lower in Tanks with High Water Temperatures
r2 = 0.39P < 0.01
16 27 38 49
Windle and Kung, University of Delaware, 2013
Summary Forage quality and silo management have
profound effects on net farm income Harvest forage crops at optimum maturity Follow best management practices for
processing and storage Use tools available to measure standards Use inoculants best suited for your needs
