Heating & Dry Matter Loss in Maize Silage

Delayed harvest has meant that maize silages are reaching or exceeding 35% DM
Get the latest Free Silage Density Calculator based on over 160 core samples

Take home Messages

Losses due to poor rolling and packing of Maize silage can exceed £2000 / 100 acres - many of these
losses are invisible and take place before moulding is seen.
The minimum feed out rate in cool weather is 4" per day, 6" in warm but Clamps should be designed for
a minimum feed out rate of 1ft per day where bulk density is (normally) inadequate.
As the dry matter of maize silages rises beyond 28-30% DM so it is more prone to heating and losses.
DM density - hence loss - is greatly influenced by the frequency, number & weight of the rolling / packing
tractor(s) AND THICKNESS OF PACKING LAYERS - MAX 4 INCHES
Careful sheeting of sides and the top of the clamp with tires touching is essential
A clean feed face and floor are essential - brush up and feed any fallen silage immediately.
5kg Urea /t applied between 30-40% DM can help to reduce heating  - and adds protein
Propionic acid at 2-3L /t  costs - £2-3 per ton and can reduce heating.  Urea and propionic acid may be used
together, as may some inoculants and urea.
MaizeCool by Biotal has received favourable reporting for high DM maize.
Propionic acid to spray the clamp face or infeed EcoTMR from Ecosyl Products & similar materials may help if feed out rates are a problem.
There is a good report on the effectiveness of inoculants from the USDA Forage Centre

 

Dry Matter Loss as Influenced by Silage Density

This example worked on Lucerne clamp silage - (Ruppel, 1992)

Density

 

Loss Per 100 acres silage

Lbs DM/CuFt

Kg/CuM

%

£

 

10

160

20.2

5656

 

14

224

16.8

4704

 

15

240

15.9

4452

 

16

256

15.1

4228

 

18

288

13.4

3752

 

22

352

10

2800

 

 

Maize Silage Density

Recommended minimum density of 14 lbs DM/ft 225kg/m

Core sample density from 81 maize clamps (Holmes & Muck 1999)

 

 

Average

 

Range

Dry Matter

%

34

 

25

-

46

 

Average Particle size

Inch

0.43

Kg

0.28

Kg

0.68

Kg

Wet Density

Lbs/CuFt

43

689

23

368

60

961

Dry Matter Density

Lbs/CuFt

14.8

232

7.8

125

23.6

378

 From this work most of the variation in silage density was accounted for by packing. DM loss is greatly
 influenced by the frequency, number & weight of the rolling / packing  tractor(s) & depth of packing layer.
Maximum packing layer should be 4".

400 hp self propelled: 100t per hour 35% DM delivered to 9ft clamp

9ft Deep Clamp Loading 100t per hour 35% DM fresh forage

 

DM Density

Base

14t

Loader tractor 6 inch layer

Kg DM/CuM

Add

9t

Tractor 50% of time

204

Add

9t

Tractor 100% of time

211

Add

2t

Weights to 14t tractor - do not use 9t tractor

208

Add

2t

Weights to both tractors 100% of time

226

Reduce to

4 inch

Filling layer

233

Reduce to

4 inch

Filling layer and use both tractors 100% time

251

Reduce to

4 inch

Filling layer and use both tractors + weights 100% time

274

 

Face Management

A minimum feeding rate of 4 inches in winter and 6 inches in summer must be maintained while feeding to minimize dry losses in typical 13lb DM /cu ft.  Clamps however should be designed to achieve twice these rates as density in UK
clamps is often sub optimal.

Feed Losses 

Silage Dry Matter

During Filling

Effluent

Gas

Top Surface

At Feeding

Total

%

%

%

%

%

%

%

Clamp - walled (incl earth)

20

2-5

4

9

2*

3** -10

20-30

30

2-5

1

7

3*

3** -10

16-23

40

3-6

0

6

4

5** -15

18-31

Clamp - no walls

20

3-6

5*

8*

2*

3** -10

21-31

30

3-6

0*

7*

4*

3** -10

17-27

40

4-7

0

6

6

5** -15

21-34

**Loss at feeding is 3-5% with good management on concrete floor. Use 4-6% for asphalt, 6-8% for macadam (har core), and 8-20% with earth floor assuming good face management. With less than good management, add up to 7% additional
 loss.

Loader Buckets versus shear grabs

Using a loader bucket to lift silage up loosens the whole face, causing cracks to penetrate deep into the silage - if there isn't a shear grab,

Scrape down the face with the bucket edge
Shear across the face with the side of the bucket
Undermine the face and use the bucket to scrape silage down onto the floor

Whatever is used, the silage face should remain tight and smooth.

Care should be taken to remove only that needed for a given feeding. Feed accumulated at the base of the feed out face will heat before being used in the next feeding.

Using the Silage Density Calculator

Preview the calculator if you do not have MS Excel Installed -  get the free viewer before downloading the calculator.

Calculations used in the clamp consider:

Height of settled silage
Dry Matter % of Fresh material
Tons per hour Fresh Weight delivered to the clamp.
Number & weight of tractors / loaders and time spent rolling / packing
Thickness of silage spread pre packing.

Key Factors in determining Dry Matter Density at the clamp are tractor  weight and thoroughness of rolling thin layers.
Twin wheels do not make a lot of difference - the bigger and heavier the tractors / loaders the better.  There would
need to be a fleet of 5ton tractors to make any real contribution to density.  At High delivery rates there needs be two
to heavy weight loader tractors.  In earth bank pits - Industrial vibrating hard core rollers can make a real difference.