Across the Capital Region of Southcentral Pennsylvania, corn silage harvest is begin
ning. If it weren’t for unusually wet soil conditions earlier on, harvest would be farther
along.
At the beginning of the harvest season, let’s take a few moments to discuss why har
vesting and filling of any type of storage structure is so important to the end product.
Each season, seed companies and agronomists are working to develop better and bet
ter com silage hybrids. However, even the best genetics and crop production system will
not be able to overcome poor management at harvest and storage.
The Silage Process
Talk to many silage producers and you quickly learn that getting an end product of
high quality silage is not always a simple task. Ensilaging any forage involves a series of
biological events that are uncontrollable after the forage enters the silo. The key factor is
eliminating oxygen in the pile.
There are four phases of ensilaging: aerobic phase, lag phase, fermentation phase, and
stable phase.
• Aerobic phase. In the aerobic phase the natural respiration of plant cells continues
in the pile. In this step plant cells, still living after chopping, continue to consume oxy
gen and release carbon dioxide. The goal is to use up all of this remaining oxygen in the
pile as quickly as possible and convert the pile to an oxygen-free or anaerobic condition.
Plant moisture, particle size, and rate of fill can greatly affect the speed of this occur
rence. If too much oxygen remains molds can quickly become established.
As plant cells continue to respire and use up oxygen, heat is released. Ideal tempera
ture in a silage pile is 80 to 100 degrees. Too much oxygen can lead to higher tempera
tures and can reduce the nutritional value of the ensilage forage.
• Lag phase. The lag phase is when the plant cell membranes are digested by bacteria
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ITT
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SEPTEMBER 21-25, 2003
FARM SHOW COMPLEX
2300 NORTH CAMERON ST.
HARRISBURG,
PENNSYLVANIA 17110-9443
PHONE (717) 787-2905
Commercial Exhibits
& Trade Show
Eastern Elite All Breeds Sale
Silage Harvest Season Is Here
Paul H. Craig
Regional Agronomy Team
Penn State
All-Dairy Antiques
& Collectibles Show
Sat. 9 a.m -5 pm; Sun 10 a.m -5 p.m ;
lues. & Wed. 8 a.m.-5 p.m ; Thurs 8 a.m.-3 p.m.
Wednesday
Eastern National Red
& White Show
7 p.m , Wed , September 24
ARY
SCHEDULE
Saturday, September 20
9:00 am to 5:00 pm - All-Dairy Antiques & Collectibles Show,
Dairy Activity Center
6:30 pm - Pennsylvania Dairy Princess Pageant,
Radisson Penn Harris Hotel
Sunday, September 21
10:00 am to 5:00 pm - All-Dairy Antiques and Collectibles Show,
Dairy Activity Center
1.00 pm - Youth Showmanship Contest, Large Arena
5:00 pm - Senior Division Fitting Competition, Sale Arena
6:00 pm - Pennsylvania Junior Guernsey Breeders Meeting & Social,
Exhibition C (Honey Room)
7:00 pm - Pennsylvania Ayrshire Youth Meeting & Social,
Mac lay Street, West Lobby
7:00 pm - Pennsylvania Junior Jersey Meeting, Exhibition C
(Vegetable Room)
7:00 pm - Careers and Opportunities Night, Dairy Activity Center
Monday, September 22
8:00 am to s‘oo pm - All-Dairy Antiques and Collectibles Show.
Dairy Activity Center
8.00 am - Invitational Youth Dairy Cattle Judging Contest
(4-H, FFA and Collegiate), Sale Arena
8:00 am - Pennsylvania Junior Dairy Show, Large Arena
7:00 pm - Judging Contest Awards Banquet, Hamsburg-Hershey
Marriott
I\iesday, September 23
8:00 am to 5:00 pm - All-Dairy Antiques and Collectibles Show,
Dairy Activity Center
8:00 am - Mid-Atlantic National Ayrshire Show, Equine Arena
9:00 am - Pennsylvania Fall Holstein Championship Show,
Equine Arena
9:00 am to 3:00 pm - “Meet a Cow” Day, Maclay Street Lobby
9:30 am - Junior Dairy Management Contest, Banquet Hall
10:00 am - Pennsylvania 4-H and FFA Dairy Judging Forum,
Sale Arena
12:00 Noon - All-American Milking Shorthorn Show, Large Arena
12:00 Noon - Eastern National Brown Swiss Show, Bulls, Calves
and Heifers, Large Arena
Wednesday, September 24
8:00 am to s'oo pm - All-Dairy Antiques and Collectibles Show,
Dauy Activity Center
B'oo am - Eastern National Brown Swiss Show, Cow Classes,
Large Arena
9:00 am - National Guernsey Show, Large Arena
12:00 Noon - Red and White Show, Equine Arena
12-00 Noon - Eastern National Holstein Show, Calves and Heifers,
Equine Arena
5 30 pm - All-Amencan Buffet, Banquet Hall
7'oo pm - Eastern Elite All-Breed Sale, Sale Arena
Thursday, September 25
8:00 am to 3:00 pm - All-Dairy Antiques & Collectibles Show, Dairy
Activity Center
B'oo am - Mid-Atlantic Regional Jersey Show, Equine Arena
10.00 am - Eastern National Holstein Show - Cow Classes,
Equine Arena
****Youth Supreme Champion and Open Supreme Champion
(selection immediately following the Holstein and Jersey
shows). Equine Arena
and release cell contents which result in additional bacterial development. It is usually
only one or two days in length and sets the stage for the next critical period.
• Fermentation phase. Since the beginning of this process the pH of the forage mass
has been decreasing from 6.7 to 5.5 as the anaerobic bacteria in the pile produce acetic
acid. At about pH 5.5, these bacteria stop growing and new bacteria that produce lactic
acids begin to grow and reduce the pH of the pile further to a pH of 3.8 - 4.2. This phase
lasts about two weeks and, eventually, the temperature of the pile drops to about 80 de
grees.
• Stable phase. Eventually the pile becomes too acidic and bacteria stop growing and
the silage stabilizes. If not enough lactic acid is formed other types of bacteria can re
form in the pile. These include listeria and Clostridia. This will not occur unless the pH
of the silage is above S.O-5.S and the moisture is high. Then butyric acid is formed in the
pile.
Creating a dense silage mass is critical to ensuring a quality feed product. Packing re
duces air space and results in rapid fermentation that reduces dry matter and nutrient
losses. Researchers at the University of Wisconsin and the USDA Dairy Forage Center
conducted bunker silo density studies in the late 19905. They determined that the min
imum density for bunker silo com silage density should be 14 pounds of dry matter per
cubic foot to minimize dry matter losses. What they found on core samples from 81 silos
was that the density ranged from 7.8 to 23.6 pounds/cubic foot. At densities of less than
10, silage dry matter losses exceeded 20 percent in 180 days. At a density of 22, losses
were 10 percent. Densities at the low end suggest little packing. Densities at the high end
are typical of many upright silos.
To ensure proper bunker silage densities, spread silage in 6-inch layers and pack with
heavy tractors, adding weights if possible. Dual wheels and tire pressures did not adver
sely affect packing. What did affect densities the most was the delivery rate layer thick
ness and the amount of packing time per ton of silage. The greater the time spent pack
ing each layer, the denser the silage. Too
frequently, packing time is determined by the
chopper and the distance to the bunker. In many
instances, producers would benefit by using sever
al packing tractors at the same time. Research has
found that the size of the equipment needed to
properly pack a bunker silo can be determined by
multiplying the tons per hour of delivery rate by
800 to get the weight of the packing equipment
necessary. For instance, if silage is delivered at 40
tons per hour, 32,000 pounds of packing tractor is
needed.
Another benefit of increasing silage density is
the increased silo capacity. Increasing density
from 12 to 14 pounds dry matter/cubic foot in
creased storage by 17 percent. Think of what 20
pounds of dry matter/cubit foot would do.
Covering Silos
Lancaster Farming, Saturday, September 13, 2003-A35
Filling a Bunker
Covering of bunker silos is a no-brainer. It is es
timated that 2S percent of the silage is in the top
three feet of most bunkers. By not sealing the si
lage, 50 percent or more of this silage will be lost.
In a 1,000-ton capacity silo this will be 75 tons of
silage, valued at more than $2,000. When properly
sealed, losses can be reduced to less than 15 per
cent.
Recent silage work with high cutting heights
have shown that by increasing harvest height from
6 to 18 inches, growers will produce a higher quali
ty silage but at a yield loss of about S percent. For
dairy fanners, milk production/acre estimates
show that when com silage yields are high, storage
space limited, and hauling distances great, in
creasing harvest height should be considered.
However with newer hybrids and better silage di
gestibility, this might not be true in all situations.
Another consideration of raising cutting height
is in silage that is too wet or high in nitrates. More
moisture and nitrates are found in the lowest por
tion of the stalks and leaving them in the field will
reduce levels in the harvested portions.
. Processing
Processing of com silage has increased in popu
larity in recent years as equipment for processing
at harvest becomes more common. Processing re
fers to squeezing the silage through two rollers on
the harvester to crush the material as it goes
through. This frequently produces greater starch
digestibility, better packing, a more uniform prod
uct at the feed bunk and allows for harvesting at a
theoretical length of cut (TLC). When using a pro
cessor the recommended TLC should be set at } A
inch and unprocessed silage cut at Vs inch TLC.
With the extremely poor planting conditions
this spring, many com fields have the risk of being
frosted this fall prior to harvest. Frosted com can
present many challenges to producers. If the frost
is light and leaves on the com crop remain green,
the plant will continue to grow and accumulate
dry matter and dry down somewhat normally.
This crop should be left in the field until proper
harvest moistures are reached.
Plants that are killed by a frost and are still im
mature will most likely contain too much moisture
for immediate harvest. This crop will dry down
slowly and lose dry matter as dead leaves are lost.
In addition, soluble plant nutrients will leach from
frosted leaves. The best option would be to leave
the crop in the field to dry to the maximum har
vest moisture level unless dry matter losses become
too great. In that case, producers can set their har
vesters to cut plants as high as possible or antici-
Cutting Height
Frosted Corn