|
SI LARGE
.B. Becker, J. M.
NATIONS
BULLETIN 734
JANUARY 1970
IN FLORIDA
P. T. D. Arnold, J. T. McCall, and C. J. Wilcox
HUME LIBRARY
JAN 12 1971
Agriculture Epe re Stati nRe Ic
Institute of Food h ri fWaF
University i url, Gafinesville "
J. W. Sites, Dean for Research
CONTENTS
Page
INTRODUCTION 3
The history of Florida silage making 3
Research objectives 4
METHODS AND PROCEDURES 5
Types of silos 5
Ensiling and covering 5
Ensiling efficiency 7
Silage density and silo capacity 7
Silage additives 8
Silage digestibilities and consumption rates 8
Comparative feeding trials 8
RESULTS 8
Nutritive value of several silages 8
Silage consumption 9
Silage additives 9
Covering silage surfaces 13
Seepage losses 15
Silage grain losses 17
Silage density 21
DISCUSSION 23
CONCLUSIONS AND RECOMMENDATIONS 25
ACKNOWLEDGEMENTS 27
LITERATURE CITED 27
Cover page: Plastic silo covers require considerable weight to prevent billowing
by wind. Welded wire holds the cover against the surface of the
silage.
SILAGE INVESTIGATIONS IN FLORIDA'
R. B. Becker, J. M. Wing, P. T. D. Arnold, J. T. McCall, and
C. J. Wilcox2
INTRODUCTION
Many dairymen and cattlemen use home grown forages as
pastures, greenchop, hays, and silages. The dairy operations
with large herds are highly mechanized and depend much on
purchased feeds. This publication presents some of the findings
related to silage investigations at the Florida Agricultural Ex-
periment Station. Some material has appeared in technical
articles and abstracts, in mimeograph form at Dairy Conferences
and short courses, but much of it has not been published here-
tofore.
The history of Florida silage making. Ensiling as a method of
preserving forages was introduced into the United States about
1876, and Pennsylvania research on silage was published in 1884
(30)." Corn silage from a 16-foot pit silo compared favorably
with that from brick silos in Leon County, Florida, according to
an 1890 report (62). Clarkson (13) believed that corn made the
best silage and produced the most feed per acre in Pasco County,
Florida. Whetstone (64) made corn and sorghum silages even
before 1890. Their silos and possibly others (44) were in use
in Florida when a wooden silo was built (19) at the Florida
Agricultural Experiment Station at Lake City in 1889. A wood
stave silo (1) was built before moving the dairy herd from Lake
City in 1907.
In those days, corn fodder, cowpea vines, and grasses were
packed tightly without chopping. Experiment station recom-
'Certain determinations in this publication were taken from Master
of Science in Agriculture theses at the University of Florida and
from original records or materials. Acknowledgements are given to
C. A. Becker (3) and G. D. Heidelbaugh (26) for their contributions.
-Becker: Dairy Husbandman Emeritus, Florida Agricultural Experi-
ment Stations, Dairy Science Department, Gainesville.
Wing: Dairy Husbandman, Dairy Science Department.
Arnold: Associate Dairy Husbandman Emeritus, Dairy Science De-
partment.
McCall: Former Assistant Chemist, Animal Science Department.
Present address: Section of Biochemistry, Mayo Clinic, Rochester,
Minnesota.
Wilcox: Associate Geneticist, Dairy Science Department.
'Numbers in parentheses refer to Literature Cited.
N
Figure 1. The first silo on the Experiment Station form at Gainesville, an
8 x 20 foot wood stave structure, stood near this dairy barn built in
1906. The building became the nutrition barn in 1929. Digestion
trials with silages, forages, dried grapefruit and orange pulps were
conducted here.
mendations on construction of silos, methods of filling, and
approximate feeding values of several silages were available in
published form in 1905 (15).
More reliable feeding values for milk production soon were
available for corn (56), Japanese cane (53), sorghum (52),
and sweet potato silages (55). Corn silage had a high feeding
value, and sorghum ranked slightly lower (54, 56). Sweet potato
silage had a high feeding value, but low yield per acre rendered
it less practical. Japanese cane was lower in value since it con-
tained no grain.
LUnder prevailing weather conditions (37), silage was recom-
mended over hay as a method of preserving foragest (61). Mono-
lithic concrete silos of large capacity were built in 1914 as shown
in Figure 2.
Research objectives. Florida research has been concerned
with methods of ensiling, ensiling efficiency, additives, and gen-
eral management, with special emphasis on problems of particu-
lar interest to Florida dairymen. When possible, biological
evaluation of silage by digestion and /or feeding trials was con-
ducted. Nearly every crop of real or potential value as silage
and available at the time was investigated.
'U I_
B ---- .. -----" -. .-
, .... .. "
S... .' ,., ,, ;
Figure 2. A new dairy barn in 1914 had stanchions for 36 cows, two silos
16 x30 feet (one visible) and a silo 10x 20 feet for experimental
use. Corn was harvested with a binder, then chopped and blown into
the tops of the silos.
METHODS AND PROCEDURES
Types of silos. Concrete tower silos were available through-
out the investigation. Three semi-trench silos (partly above
ground level) were used for several years. Two sisalkraft silos
were found impractical because of bird and rodent damage.
Four pilot concrete silos were constructed in 1935 (43 inches
inside diameter by 71 to 84 inches depth) and replaced in 1952
with six concrete pit silos (48 inches diameter, 96 inches deep).
A concrete bunker silo of 400-ton capacity was available for use
in 1961.
Ensiling and covering. Several methods of covering top sur-
faces of silages were employed successively. In early years, top
surfaces of cut forages were packed by tramping as the silos
were being filled. Two-ply roofing paper was lapped at the
edges and up the side of the silo wall, and weighted with cut
forage. Edges were "walked" daily to keep the cover close
against the forage as the silage settled. Moist burlap was laid
over the surface in the pilot silos, covered with two-ply roofing
A
BB
Figure 3. Forages are now (a) chopped in the field, (b) distributed evenly
in bunker silos and covered with plastic to minimize surface spoilage,
and (c) removed with several types of mechanical unloaders.
paper and additional cut forage. Then about 2 feet of soil were
mounded over the surface flush with the surrounding ground.
When black polyethylene and black vinyl plastic films became
available, they provided more nearly air-tight covers (27) with
a thin layer of soil to hold the plastic against the forage. Poly-
ethylene-coated canvas, lined with a separate layer of vinyl film,
was used for silos which were 8 feet in diameter and 5 feet tall.
These were practically air-tight, except for a small pipe in the
bottom that provided drainage of silage juices. 'A minimum
ensiling time of 45 days was practiced throughout for all silos)
Ensiling efficiency. Total weights of forage in and silage
out were obtained whenever practical. Three 10-kilogram (22
pounds) samples of forage were placed into moist porous bags
which were distributed at intervals in the silos as filling pro-
gressed. A strip of moist burlap was placed slightly above each
sample bag as a precaution against damage at time of removal.
Corresponding 1-kilogram (2.2 pound) samples of freshly cut
forages were taken at filling for parallel proximate analyses.
Silage density and silo capacity. Densities of the settled
silages in the semi-trench silos (partly above ground) were
computed from depth, width, and length measurements. Depths
of settled silages were measured at four points on the wall of
the concrete pit and upright silos as silages were removed. For
10 seasons, density of prolific-type corn silage was determined
from a concrete monolithic silo 10 feet in diameter by 20 feet
in height.
Silage additives. Additives included dried citrus pulp, black-
strap and citrus molasses, citrolas, sodium metabisulfite, urea,
antibiotics, and ground snapped corn.
Silage digestibilities and consumption rates. Digestibility
coefficients of certain silages were determined by fecal collection
(24). Silages were fed consecutively from the larger pilot silos
(4 feet x 8 feet deep). The chromogen-ration technique (33,
48) was employed with grab fecal samples after a preliminary
feeding period. Consumption rates of silages were adjusted
linearly to a 1000-pound live weight basis (69) 'for the groups
of animals. Silages exerted a favorable influence on rumen diges-
tion in producing fatty acids needed for synthesis of milk fat
(4). The dry matter of silages from the same crop is slightly
less digestible than in fresh forages. (39, 67, 69).
Comparative feeding trials. Steers were fed continuously
with one of several silages in three consecutive winter fattening
trials from semi-trench silos. The double-reversal method of
feeding was followed with soybean silage and Crotalaria inter-
media silage versus No. 1 green federal grade alfalfa hay in
each of the three 90-day trials with milking cows.
RESULTS
Nutritive value of several silages. Early Florida trials showed
soybean silage to be equivalent to alfalfa hay on the dry matter
basis in rations of milking cows (9). Crotalaria intfcrmedi'
silage (42), harvested at the bud stage of maturity (27% dry
matter), provided 2.1K/ of digestible crude protein and 10.7%
of total digestible nutrients (TDN). At this stage, 107 pounds
of silage dry matter equalled 100 pounds of No. 1 green alfalfa
hay for feeding to milking cows (49). Plain C. intermedia, silage
had only medium palatability. The plants increased in fiber con-
tent early during growth, and yields of desirable forage per acre
were too low to recommend it over some other legumes. Dry
matter content and digestibility of 10 silages are listed in
Table 1.
Cattle gained less on sugarcane silage than on sorghum or
Napiergrass silage (59). This could be because the nitrogen-
free extract of sugarcane is high in soluble sugars, which break
down by fermentation to organic acids. With sorghum silage
rated at 100, based on average daily gains of steers, gains from
sugarcane rated 70. Shocked sugarcane excelled sugarcane silage
with carpet grass as roughage for wintering beef cattle (31).
TDN contents, on a dry matter basis, of fresh, shocked, and
ensiled sugarcane were 62.0';. 57.5' and 45.4; respectively
(41).
S'7 ... conisiuptiov. Bacteria that produce an acid-type fer-
mentation depend on readily available carbohydrates for their
development. When such compounds are present, acid-forming
bacteria are likely to predominate. Otherwise, putrefactive
(decay) bacteria may predominate. The latter attack protein
compounds, from which the end-products have largely objection-
able odors.
Adding readily available carbohydrate materials to grass
forages at ensiling had little additional favorable effect on con-
sumption rates. The aroma of plain saccharine grass-type silages
was mainly characteristic of a desirable acid-type fermenta-
tion. The amounts of silages eaten daily, adjusted to a 1000-
pound live weight basis, are listed in Table 2. When readily
available carbohydrates had been added to legume forages, it
was noticeable from increased consumption rates that produc-
tion of an acid-type rather than a putrefactive fermentation in
the legume silages rendered them more palatable to the animals.
Each of the green forages had been harvested on the same days
from the same fields.
Siloc additiirc.s. Grass-type forages investigated include
corn, Napiergrass, oat forage, Pangolagrass, pearlmillet, sor-
ghum, and. sugarcane. Legume silages included alfalfa, cowpea,
hairy indigo, soybean, sweet yellow lupine, and white clover.
One control silo in each series contained no additive, for com-
parison with one or more additives in the series harvested at
the same growth stage when ensiled. Average percentages of
nutrients preserved in the silages are assembled in Table 3.
Additives were dried citrus nulp. ground snapped corn, molasses,
sodium metabisulfite, urea, and antibiotics. Molasses and other
additives improved palatability and consumption rates of some
silages. Kenaf (68) is a recent introduction on trial as silage
in Florida.
Dried citrus pulp and ground snapped corn appeared to re-
duce seepage losses of nitrogen-free extract in the grass silages.
Table 1. Digestible nutrients of grass and legume silages with several additives.
Nutritive value on fresh basis
Number Digestible Total
of Dry crude digestible
Silages cattle Additives per ton matter protein nutrients
pounds % % %
Alfalfa, early bloom
Crotalaria intermedia,
bud stage
Hairy indigo, pre-bloom
Soybean, pre-bloom
Sweet lupine, pre-bloom
Napiergrass, nearly
mature
4 none
4 150 snapped corn
4 150 citrus pulp
4 8 sodium metabisulfite
4 none
4 none
4 150 citrus pulp
4 none
4 150 citrus pulp
4 8 sodium metabisulfite
4 none
4 125 citrus pulp
4 7 sodium metabisulfite
4 none
Oats, immature, wilted
Oats, mature
Pangolagrass, immature
Pangolagrass, mature,
wilted
Pearlmillet, pre-bloom
Sart sorgo, with seed
heads
3 none
4 150 citrus pulp
4 250 citrus pulp
4 none
4 5 g. zinc bacitracin
4 150 snapped corn
4 none
4 150 citrus pulp
4 250 citrus pulp
8 8 sodium metabisulfite
4 none
4 150 citrus pulp
4 250 citrus pulp
4 none
16 150 snapped corn
8 300 citrus pulp
12 none
Table 2. Daily consumption of legume and grass silages fed free choice to
dairy cattle.'
Number Additive at ensiling
of 150 lbs. citrus
Silages cattle None pulp per ton
Legume forages pounds pounds
Alfalfa, early bloom 4 62.2 81.1
Hairy indigo, pre-bloom 4 64.5 81.3
Soybean, pre-bloom 4 70.8 72.0
Sweet lupine, pre-bloomn 4 66.1 81.5
Grass forages
Oats, immature, wilted 4 55.9 55.6
Pangolagrass, mature, wilted 4 58.0 40.03
Pangolagrass, immature 4 59.6 54.2
Pearlmillet, pre-bloom 4 79.1 81.0'
'Daily consumption is computed per 1000 pounds live weight of aninm ls.
Sweet lupine was the only plain legume si:li'e without putrefactive odor. Only 12-
pounds of citrus pulp were added per ton at ensiling.
'Sand contamination.
'300 pounds of citrus pulp per ton of forage at ensiling; 8 cattle used in this trial.
Dried citrus pulp was similarly effective with legume silages
(10). These highly digestible added carbohydrates are major
sources of energy in grass silages and contribute substantially
to legume silages.
r Increased proportions of ether extract (crude fat) come
from breakdown of nitrogen-free extract (soluble sugars, etc.)
and possibly some crude protein by the ensiling fermentation.,,/
This action largely forms organic acids such as acetic, etc.,
which are soluble in ether. They appear increasingly in this
fraction of the dry matter. Little change took place in the crude
fiber compounds, and there was no migration downward. Slight
losses of mineral ash were in unmeasured seepage. The apparent
increase in crude protein retained with urea additive arose from
the customary computation of total nitrogen multiplied by the
factor 6.25, and listing the product as crude protein.
Fresh citrus pulp from a cannery, and citrus press cake,
were ensiled (6) to conserve food during World War II before
there were adequate facilities to convert much of it into dried
citrus pulp. The product ensiled satisfactorily, but dried citrus
pulp was considered more versatile as a feed and as an absorp-
tive ingredient with legume and high-moisture grass silages
(10). Citrolas was a commercial mixture of fine citrus pulp
particles and citrus molasses.
Cullison (16) found sorghum ensiled with 10 pounds of urea
per ton to be adequate for maintenance of beef cows over 76
days. This compared with an average loss of 47 pounds by cows
fed untreated silage. In the next year, sorghum was ensiled at
the Florida station (17) with 0, 10, 30, and 50 pounds of urea
per ton. Dry cows preferred the control silage and that with 10
pounds of urea per ton over the silage with 30 pounds of urea.
Some urea broke down to free ammonia. Cows refused to eat
sorghum silage containing 50 pounds of urea per ton until the
free ammonia had volatilized from it.
When 10 pounds of urea were added per ton of high-moisture
Gahi pearlmillet (66), cattle ate less of it than of the control
silage. Their blood-ammonia and blood-urea levels increased
above those observed while receiving the control silage. These
blood contents were even higher when 15 pounds of urea had
been added to the millet at ensiling, but did not reach the critical
ammonia level of 4.0 milligrams per 100 milliliters of blood
(18), and no animal was lost. Less of the silage that contained
the higher level of urea was eaten.' Since too much urea re-
duces palatability and intake of urea-sorghum silages, the prac-
tice has become widespread of adding only 0.5%7 to 1.0' of
urea when ensiling grasses to increase their protein equivalent
value.
Based on feeding trials with cattle, the present recommended
practice is to limit urea in grass-type silages to not over 10 to
15 pounds per ton of forage when filling the silo. This amount is
reduced when urea is fed also in the concentrates or mixed in
molasses which the animals consume. Urea is not added to
legume silages, which are already adequate in protein content.
Precaution is necessary to avoid urea toxicity (18) in animals
from too large an intake in a short time.
Six antibiotics, zinc bacitracin, chlortetracycline, oleando-
mycin, oxytetracycline, procaine penicillin, or streptomycin, were
added in water solution at 5 grams per ton of chopped Gahi
pearlmillet forage (70). Consumption by dairy cattle was de-
pressed with silage containing chlortetracycline and oxytetra-
cycline. Procaine penicillin and zinc bacitracin appeared pre-
ferable, if an antibiotic was to be used as an additive. Efficiency
of preservation of nutrients was not computed.
Digestibility of the silage was determined by the chromogen
ratio technique. Heifers consumed an average of 61 to 103
pounds of silage per 1000 pounds of body weight. Results of
these trials with Gahi pearlmillet silage containing antibiotics
are listed in Table 4.
Covering silage surface. Chopped waste forages were used
earlier to cover the good forages, so that mostly the less desirable
Table 3. Effect of additives on preservation of nutrients in grass and legume forages as silages.
Additive
None
Citrus pulp
Ground snapped corn
Molasses
Sodium metabisulfite
Urea (in sorghum)
None
Citrus pulp
Ground snapped corn
Molasses
Sodium metabisulfite
Number of Dry
observations matter
15 85.7
10 90.8
2 97.3
4 88.3
5 89.7
Percentage of nutrients preserved
Crude Crude Ether
protein fiber extract
Grass forages
86.0
82.5
73.0
88.3
73.2
113.0
80.0
89.5
83.3
93.6
83.6
94.6
91.0
85.6
93.4
95.0
99.0
Legume
92.6
96.5
81.8
98.4
97.9
123.4
143.1
115.6
112.8
159.8
166.9
forages
152.3
147.5
190.0
144.2
121.9
in silages
Nitrogen-
free extract Ash
77.6 92.1
81.9 91.4
74.2 86.5
80.4 96.8
80.3 98.9
Table 4. Use
of antibiotics in Gahi pearlmillet silage.
Antibiotics
Green forage
Zinc bacitracin
Chlortetracycline
Oleandomycin
Oxytetracycline
Procaine penicillin
Streptomycin
Dry Crude
matter protein
% %
8.1 74.2
10.1 76.9
12.2 70.7
13.8 66.3
12.3 77.4
10.4 79.1
13.2 69.5
Digestibility
Organic
1 matter
Nutrient value' Consumption
per 1000 lbs.
DCP2 TDN live weight
%
0.93
0.64
0.88
1.02
0.92
0.89
0.95
10.7
6.2
7.6
8.2
8.0
7.3
8.7
lbs.
102
93
61
102
67
103
89
10n the fresh basis as fed.
2Digestible crude protein.
top material would be lost by decay. Sometimes feeding began
as soon as the silo was filled, to avoid surface spoilage. Cows
accepted the freshly chopped corn well for two or three days.
They ate less while ensiling fermentation was continuing, until
finished silage was reached.
The top layers of forage were frequently tramped during
filling to reduce air content. Chemically treated kraft paper was
tested as a cover one season, with only partial success. Fermen-
tation products attacked the paper and caused it to disintegrate.
Two-ply roofing paper, lapped 6 to 8 inches at the edges and
upward on the silo wall, was reasonably effective in reducing
contact with the air. Rodents burrowed under the paper, causing
excessive spoilage. Roofing paper was unavailable once during
World War II. Over 5 tons of surface spoilage were removed
from the 10-foot tower silo without cover, in contrast with
around 1300 pounds or less around the sides of the silo under
the two-ply roofing paper.
Air did not penetrate black polyethylene and vinyl plastics,
nor were the plastics attacked by end-products of silage fer-
mentation. Such plastic covers were used to cover silages in 1954
and later. Surface spoilage under them occurred only when air
penetrated around the edge of the plastic or when the plastic
was torn by accident or carelessness. The material has been
used and recommended where it can be weighted down against
winds and protected from breakage by animals walking over
or chewing -les in it.
Seepage losses Seepage can carry away soluble nutrients,
especially from high-moisture silages. Shaw et al. (57) reported
8.66% of the dry matter from corn silage, mainly fermentable
carbohydrates and nitrogen compounds, lost due to seepage.
Ether extract gained in amount in the silage. Losses of crude
protein in seepage from alfalfa-molasses silage in New Jersey
(20) ranged from 0.88% to 2.44% of the dry matter ensiled,
excluding seepage between wood staves of the silo. Otis (43)
measured a loss of 6.5% (63/1 tons) as juice from alfalfa silage.
The juice carried away 6.4% of the crude protein, 5.5% of the
mineral ash, and 0.4% of other solids ensiled. The juices drained
away 1.6% of the total dry matter.
Archibald and Gunness (2) collected seepage from mixed
grass-legume silages during seven seasons. The seepage carried
away 0.54% of the dry matter of the forages. The seepage
contained 4.6% to 10.0% solids, including 2.1% ash, 0.3%
nitrogen (1.9% crude protein equivalent), soluble carbohydrates,
and some organic acids. There was less seepage when the crop
was wilted first, or when ground corn and wheat were added
as absorptives. Jones (29) added dried beet pulp at 60, 110,
and 160 pounds per ton of green forage. The pulp absorbed
twice its weight of juices. He estimated, from seepage measured
and analyzed, that this absorbent saved sufficient soluble nu-
trients that otherwise would have seeped away, to add $2 per
ton to value of the vetch-and-oat silage.
Virginia workers (46) compared seven preservative tech-
niques relative to seepage losses from chopped alfalfa silage, as
follows:
Corn & Brewers'
No Sulfur cob dried Beet
additive dioxide Molasses meal grains pulp Wilting
Seepage, Ibs 12.67 32.6 16.4 0.7 0.4 0 0
Seepage solids, % 7.6 7.7 10.0 16.9 14.1 0 0
Browning and Lusk (11) reported an 8.6%c dry matter loss
by fermentation and 1.2% seepage from RS-610 grain sorghum
silage in a gas-tight silo. The sorghum silage had 27.5% of dry
matter when fed. Miller and Clifton (35) analyzed seepage
records published for 38 silos. The percentage of dry matter
lost was equal to 17.614 (.538 x %9 dry matter of forage
ensiled). This formula may not apply when absorptive additives
are used.
Adding 200 pounds of dried beet pulp per ton (25) when
ensiling mixed Ladino clover and orchard grass conserved 38
pounds of dry matter per ton at a cost of 15.1 pounds of beet
pulp dry matter. Palatability and feeding value of the silage
were enhanced.
An attempt was made to observe the relation of additives to
seepage from certain silages. Weighed amounts of dried citrus
pulp were placed in burlap bags beneath the forage in 23 pilot
silos. The bottom area of a 4-foot pilot silo covered 12.54 square
feet. The upper surface of a bag with pulp extended less than
8.25 square feet, affording interception of gravitational moisture
directly from less than 65.7% of the cross section. Dried citrus
pulp in the bags was capable of absorbing and retaining up to
145% of its original weight. The increased weights of bag con-
tents, on a percentage basis, are assembled in Table 5. This seep-
age contained soluble nutrients that otherwise would have been
lost. Fermentation losses in the ensiled citrus pulp were not
measured.
Pearlmillet (70% to 75% moisture) released so much juice
that all bags of dried citrus pulp beneath it were saturated. The
pithy stalk of Sart Sorgo, of similar moisture content, released
little seepage that was absorbed. The bags of citrus pulp beneath
alfalfa, hairy indigo, Pangolagrass, and soybean forages (con-
taining 77.0'% to 88.7'( moisture when ensiled), increased an
average of 108.3% in weight from absorption of silage juices.
When 150 pounds of dried citrus pulp were incorporated with
the forage at ensiling, the seepage absorbed in the bagged pulp
beneath averaged 89.5% in increased weight. Slightly less seep-
age juice was absorbed under silage in which 250 pounds of pulp
had been incorporated at ensiling.
With no allowance for fermentation losses within the bagged
pulp, three such bags contained 32.6, 31.6 and 33.2 pounds of
dry matter when removed. This was an increase of 2.4% in dry
matter--mainly in ether extract (ether soluble fatty acids)
and crude protein. Any allowance for fermentation losses in the
original pulp would increase the estimate for dry matter ab-
sorbed with the juices. Cows preferred this bagged pulp to the
silages above it.
Since crude fiber was least subject to gravitational movement
in seepage, the ratios of other constituents to crude fiber of the
bagged citrus pulp were computed, and presented in Table 6.
As the amount of citrus pulp incorporated in the forage at en-
siling increased, less nitrogen-free extract and ether extract
seeped downward to be absorbed in the bagged pulp.
Silage grain losses. Grain losses in the silo are of interest.
Literature on this item has not been assembled previously.
Research by the senior author at the Oklahoma station in co-
operation with W. D. Gallup, and results at other stations, were
assembled in the interest of completeness. Less nutrients are
lost from the grains during ensiling than occur normally with
seed grains (36) due to respiration in dry storage. Florida
farmers mentioned in 1890 (44) that grain preserved in corn
silage was not subject to loss by birds, rodents, and weevils
that occurred in the field. Muntz (40) reported that oats lost
7.2% more dry matter in the atmosphere than in an air-tight
container, whereas corn lost 10% more in six months. Protein
losses were negligible. After death of the germ, loss was re-
duced from lowered enzyme activity. Ensiling of grains reduced
such depreciation. Dox and Yoder (21) and Russell (51) found
that starch of corn grain appeared unaffected by ensiling fer-
mentation. Shaw and Norton (58) determined that calves, year-
Table 5. Percentage increases in weight due to seepage absorbed by bags of dried citrus pulp beneath the forages, as affected
by additives, neglecting fermentation losses of bagged pulp.
Additive per ton
Forage Moisture of Ground Sodium
ensiled forage Citrus pulp snapped corn metabisulfite
None 150 lbs. 250 lbs. 150 lbs. 8 lbs.
------------------------------------- ---------------------------r ------------
Alfalfa, bud stage 86.78 114.29 -
83.56 72.86 -
83.01 111.43
82.32 81.40
Alfalfa, early bloom 82.85 103.41
75.76 72.861
Hairy indigo 74.02 105.71 -
77.37 100.00 -
77.97 104.29
Soybean, Jackson 83.84 148.57'
80.28 118.57 -
82.53 124.29
Pangola, long 79.97 89.25- -
77.57 77.24 -
64.65 68.18
Pangola, chopped, early bloom 80.78 88.57
77.57 78.57
76.61 50.00
Pearlmillet 70.83 151.43 --
75.50 145.71 -
74.01 -- -145.71
75.54 140.00
Sart sorgo 74.50 45.00 -
5Citrolas, a pelleted combination of citrus fines and molasses, replaced citrus pulp.
Water table may have affected weight of pulp beneath pearimillet and the untreated soybean forage, as the bags were saturated.
Table 6. Relation of the amount of additive incorporated with the forage at ensiling, to chemical analysis of citrus pulp in
burlap bags under the silages.
Additive Dry Crude Crude Ether Nitrogen
per ton Moisture matter protein fiber extract free extract Ash
lbs. ------------- .--------------------------- -
Citrus pulp
None ()heore ensiling) 12.90 87.10 6.46 11.50 5.12 59.27 4.92
150 50.65 49.35 3.58 6.85 3.34 32.80 2.79
250 47.88 52.12 4.17 7.30 2.78 34.83 3.02
Sodium mctabisulfite
S8 36.73 63.27 4.06 7.52 3.26 45.17 3.26
Original pulp' 11.95 88.05 7.35 11.98 3.24 59.87 5.61
Ratios of other groups to crude fiber
Citrus pulp
None (before ensiling) 7.57 0.61 1.00 0.45 5.15 0.43
150 7.20 0.52 1.00 0.49 4.79 0.36
250 7.14 0.57 1.00 0.38 4.77 0.41
Sodium metabisulfite
8 8.41 0.54 1.00 0.44 6.01 0.43
Original pulp 7.34 0.61 1.00 0.27 4.99 0.47
'The average of 14 samples analyzed.
lings, and cows voided 2.98%, 5.48%, and 10.06% of whole
oats and 6.28%, 10.77%, and 22.75% of shelled corn consumed,
respectively. Losses of whole grains when fed as silages were
less than when fed in dry form. At the Florida station (5),
dairy calves, yearlings, and cows utilized crimped oats with
losses of only 0.43%, 0.21%, and 0.50% in the feces, agreeing
with the trials at the New Hampshire (14) and Purdue Univer-
sity experiment stations (65).
Moore (38) computed the loss of whole grain from sagrain
sorghum silage at 25.7% of the grain dry matter consumed by
cows. The loss was 15.7% of the total dry matter in the silage.
In trials conducted at Clemson College (32), corn kernels and
sweet sorghum grain were separated by washing manure from
cows through screens. The grain recovered was calculated at
1.86'. of the dry matter in corn silage, and 27.55% of the sor-
ghum grain in silages eaten by four cows. Total manure outputs
of four cows over 10 days were separated with water and screens
at the Oklahoma station (7, 8). Those animals voided 8.47%
of the grain (4.36% as whole kernels from corn silage, 33.9%
of sweet sorghum and 49.44% of kafir grain consumed in the
respective silages). Similar losses in Kansas trials (23, 47)
were 42.9% of Kansas Orange cane seed and 30.4% of Atlas
sorghum seed from the silages eaten. Michigan workers (28)
recovered 2.7%, of whole kernels from feces of 12 cows that ate
corn ensiled in the early dent stage of maturity. In these trials
(7, 8, 23, 47), composition of the whole kernels had not been
changed significantly by passage through the digestive tract.
Browning and Lusk (12) found that the percentage of seed from
grain sorghum silage that heifers voided undigested in the feces
increased rapidly as maturity of the forage advanced.
Ward et al. (63) crushed sorghum seed heads (hard dough
stage) in a hammermill and returned them into the silos. They
noted differences of 4.5% and 8.7% in disappearance of whole
seeds in manure of cattle fed Dekalb FSla and White Sourloss
sorghum silages containing treated heads as compared with those
whole on control silages. Size, hardness, and stage of maturity
of seeds affected the proportion that passed undigested through
the digestive tracts of cattle.
An investigation begun by Eckles and continued by Ragsdale
and Turner (45) found dry matter losses of 15.12% in 16 pro-
tected corn shocks as compared with 4.01% in 20 silos, dis-
regarding surface spoilage. Milner (36) pointed out that grains
respire less when dry and at low temperature.
Woodward (71) held 29 kinds of weed seeds in corn, grass,
or alfalfa silages for over six months. Only hard seeds of bind-
weed, American dragonhead mint, L spedo: sccricea, and sweet
clover germinated after removal. The other kinds decayed and
disintegrated. The ensiling process devitalized kafir and sweet
sorghum seeds (23). A review concerning weed control (50)
stated that most weed seeds, except those with hard seed coats,
were destroyed during the ensiling process. Only 28 of 1100
seeds germinated after remaining in silage for 41 : years. Seeds
that remained viable included wild morning glories, garden
morning glories, velvet leaf, giant ragweed and water-grass
seeds. Ensiling reduced but did not exclude scattering of weed
seeds through fresh livestock manures.
Silage density. Densities of silages vary with moisture con-
tent of the forage, proportion of grain, character of the stalk
or stem, and depth (overhead weight) in the silos. This infor-
mation applies when (a) computing size of a silo with relation
to the herd to be fed, (b) length of the feeding period, and
(c) estimating the amount of silage remaining after a part has
been removed off the top. Computations at the Missouri and
Kansas stations (22) were b-s-ed oi records of settled corn and
sorghum silages. These were computed from cubic feet of silage
sampled at different depths when being taken from the silo.
McCalmont (341) computed silo capacities from the green
forage required to fill five silos during several years at the Dairy
Research Center, Beltsville, Maryland. Method of computing
densities was not stated.
Silage densities in Florida were calculated from total amounts
of silage removed and the averages of measurements on the silo
wall. Changes in densities were interpolated between the upper
and lower quantities and listed upward from the bottom of each
upright or pit silo. Capacities of three semi-trench silos were
computed from measurements of the face of the silage and linear
dimensions.
Three semi-trench silos 35 feet long, 8 feet wide at the
bottom, and 10 feet at the top. were used in comparison of
Napiergrass, Texas Seeded Ribbon Cane sorghum, and Cayanna
10 sugarcane silages (59) used in rations for fattening steers.
Densities were computed from the total volume of settled silages
fed out over two seasons of 177 and 172 days. Some edge
spoilage occurred despite covering with two-ply roofing paper,
weighted with a layer of soil. Volumes and weights per cubic
foot of settled silage are listed in Table 7. The Napiergrass and
Table 7. Density of settled silage in semi-trench silos.
Crop and year
Napier grass
First year
Second year
Sorghum
First year
Second year
Sugarcane
First year
Second year
Silage removed
Ensiled Sound
Ibs. Ibs.
Volume Weight per
Spoiled occupied cubic foot
lbs. cubic ft. lbs.
103,840 68,425 20,358 2,564.5 34.62
142,720 82,846 32,144 3,173.6 36.23
149,380 95,836 12,961 3,016.2 36.07
120,900 83,800 10,683 2,408.3 34.80
126,120 89,218 16,340 3,558.3 29.67
107,000 51,480 38,594 3,286.3 27.41
sorghum silages were about equally dense at around 35 pounds,
and sugarcane silage around 28.5 pounds per cubic foot.
The average density of prolific-type corn silage over 10
seasons at the Florida station (Table 8), based on total weights
of silage removed, varied less than 10% from determinations
at the Missouri and Kansas stations (22) from cubic feet of
silages sampled at different depths. The silages at Beltsville
(60) may have had higher moisture contents than the prolific-
type corn silage in Florida.
Table 8. Weight per cubic foot of settled silage in upright silos.
Corn silage at
Mo. and
Kans. (22)
pounds
32.0
32.7
33.4
34.1
34.8
35.4
36.0
36.6
37.4
38.0
38.4
38.8
39.2
39.6
40.0
40.2
40.4
40.6
40.8
41.0
42.0
43.0
Corn silage at
Beltsville
(60)
pounds
17.7
29.2
33.9
37.2
39.8
41.8
43.6
45.0
46.1
47.1
47.9
48.7
49.3
49.9
50.5
50.9
51.3
51.7
52.1
52.4
53.7
54.4
Silage from 10 ft. silo
Corn Soybean (11)
pounds pounds
28.6 28.2
29.6 30.4
30.6 32.7
31.0 35.1
32.1 37.3
33.0 39.1
33.9 41.5
34.8 42.8
35.7 44.2
36.6 46.2
37.5 47.5
38.3 49.41
39.2 52.41
58.01
'Values at the greater depths were influenced by gravitational moisture. Sorghum and
kafir silages did not differ widely from corn silage.
Depth in
silo
feet
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
25
30
Friction on the walls of small diameter silos may permit
less settling of silages than would occur where this is not a
factor. The pilot silos from which densities in Table 9 were
computed were 43 and 48 inches in diameter. Wilting oats and
white clover prior to ensiling permitted those forages to settle
more than when not wilted. However, two operations during
harvest caused mechanical contamination with sand. Relative
densities of six legume and seven
silos are presented in Table 9.
Table 9. Weights per cubic foot
different depths in pilot silos.
Number
of silos
Legumes
Alfalfa
Cowpea
Hairy indigo
Soybean, Jackson
Sweet
yellow lupine
White clover
White clover,
wilted
Grass-type forages
Napiergrass
Oats
Oats, wilted
Pangolagrass, long,
wilted
Pangolagrass,
chopped
Pearlmillet
Sart sorgo
Sorghum,
Texas Seeded
Ribbon
Sugarcane,
Cayanna 10
mn grass-type forages in 63 pilot
of settled grass and legume silages at
Depths in silos, feet
1 2 3 4
pounds
35.2 41.6 46.6 47.
46.7 47.8 49.1 50
45.3 47.8 50.3 52
42.9 44.3 45.9 47
3 49.4 52.7 56.1 59.9
3 35.6 36.6 37.6 39.3
3 46.4 47.7 48.6 49.5
25.7 27.2 28.7 30.2
43.5 50.6 53.7 54.1
29.5 31.0 32.5 33.2
9 34.2 35.3 36.0 37.6 37.8
1 33.8 34.2 34.6 37.7 39.0
DISCUSSION
Larger dairy herds and increasing mechanization of feeding
operations are changing dairy facilities. A tendency toward
larger silos is entailed. Field choppers are used to harvest
forages, and bunker or large-diameter silos are adapted for
mechanical loading, unloading, and feeding of the forage part
of the rations.
Ensiling does not increase the total value of a forage, but
Crop
forages lose less nutrients when stored as silage than as hays.
Less shattering and loss of leaves occur during harvest for the
silo, so that food nutrients are preserved more efficiently than
as hays or fodders. Only sun-cured hays contain more vitamin
D. Also, forages can be ensiled when near optimum nutritional
value, almost irrespective of weather conditions.j
,Ensiling forages may reduce the amount refused by animals.
Less whole grains are voided in manure from silages than from
the same kinds of whole grains fed in dry form.
Corn and the sorghums have made silages highest in feeding
value.
Silage was satisfactory in preventing or correcting sub-
normal butterfat percentages in milk (4). Slight feed flavors
of milk can be avoided by feeding silages after milking rather
than just prior to or during the milking period.
Density tables and consumption rates of silage provide some
information for calculations. Dimensions of a silo need to be
planned in advance according to the number of animals that
will be fed and length of the feeding period.
Plastic covers over the silage reduce surface spoilage and
total fermentation losses. The forage saved more than offsets
cost of the plastic cover.
Additives have been incorporated with forages at ensiling
for several purposes: to facilitate desirable acid-type rather
than a putrefactive type of fermentation, reduce or retard fer-
mentation losses, decrease seepage of soluble nutrients, increase
palatability, and enhance nutritive value of the silage to be fed:
The acid-type silages have been more acceptable, favoring
increased consumption by cattle, Saccharine plant juices in the
forage favor desirable acid-type rather than putrefactive fer-
mentation. Addition of readily fermentable carbohydrates such
as molasses, ground cereal grains, absorbents such as corn-and-
cob meal, dried beet pulp, citrus pulp, and brewers' dried grains
contribute to acid-type fermentation.
Dilute phosphoric acid was used at several experiment sta-
tions. Sodium metabisulfite was tested extensively. It produced
sulfur dioxide in contact with moisture (sulfurous acid) which
attacked metal machinery, masonry and metal silo walls, and
could harm workmen while filling the silo. This product has
been largely discontinued because of injurious side effects.
Seepage losses of soluble nutrients can be reduced with ab-
sorptive additives such as dried beet and citrus pulps, ground
snapped corn or similar products.
Some dry matter is lost during the ensiling process. Most
recoveries will be close to the average of 87.6c as found in
these trials. Additives had slight influence on preservation of
nutrients, but some decreased seepage losses and influenced the
type of ensiling fermentation. Preservation of protein varied
more than that of other nutrients. Citrus pulp and molasses
were most effective. and ground snapped corn was the least
effective additive. Unless putrefaction took place, loss of nitro-
gen would be confined largely to gravitational movement of the
soluble compounds. Slight loss of mineral constituents may have
been mainly in gravitational movement of seepage juices down-
ward.
Limited additions of urea have enhanced the crude protein
value of silages. Silage may well be a safer carrier of this
additive than are mixed concentrates.
Crude fiber underwent little loss. Nitrogen-free extract,
mostly starches and sugars, decreased from biological and en-
zymatic action in the silage. Losses paralleled those of the dry
matter. The largest part of ether extract resulted from con-
version of soluble carbohydrates into ether-soluble organic acids.
Soluble sugars apparently were the main part of the nitrogen-
free extract lost.
Some carbon monoxide and nitrogen oxide gases are pro-
duced early in the ensiling fermentation. These are toxic. Work-
men should n)ot attempt to enter a frecshly-filled silo because
of some toxic gases and lack of oxrygen. Some silage gases are
harmful in confineement.
CONCLUSIONS AND RECOMMENDATIONS
The silage investigations warrant the following conclusions
and recommendations based on experimental results and obser-
vations:
1. Any forage acceptable to cattle in green form can be
preserved satisfactorily as silage when harvested prop-
erly and stored above the water table with air excluded.
2. Feeding value of the silage depends directly upon the
quality of forage ensiled. Crops growing rapidly are
preferred. Exceptions are oats in the early bloom stage,
and corn or sorghum in the dent or hard dough stage.
The lower leaves have begun to turn brown and sugars
are changing to starch in the plants.
3. Chopped forage is easier than long forage to place in,
and remove from, the silo.: Chopped forage tends to
pack closer and reduce contact of air. Forages wilted
before ensiling occupy less space, but require two oper-
ations to harvest. Some forages may become contami-
nated with soil in the pick-up operation.
4. Plastic covers allow less air leakage than other covers,
and can reduce surface spoilage and fermentation losses.
5. Good methods of harvesting, ensiling, and covering silos
should preserve S"1 to 90%' of nitrogen-free extract.
Some mineral ash leaches downward. Ether extract in-
creases by formation of ether-soluble fatty acids from
breakdown of sugars and some nitrogen compounds.
6. Cattle generally eat more of the desirable acid-type than
of the putrefactive-type silages. Saccharine plants such
as corn, sorghums, etc., naturally favor desirable acid-
type fermentations. Addition of molasses or dried beet
and citrus pulps can provide sugars to facilitate activity
of desirable acid-forming bacteria when ensiling legumes
and non-saccharine grasses. Sixty pounds of molasses
per ton of chopped grasses or 80 pounds with legumes
proved satisfactory for this purpose.
7.'- Dried citrus pulp or beet pulp and similar absorptive
products reduced seepage by taking up more than their
weight of silage juices, retaining sufficient soluble nu-
trients to more than offset their ensiling losses.- They
add to feeding value and palatability of the silages, and
increase efficiency of preservation slightly. When 250
rather than 150 pounds of dried citrus pulp were incor-
porated per ton of forage, absorption increased but at
a lesser rate.
8. Although 10 to 15 pounds of urea added per ton of corn
or sorghum at ensiling resulted in only slightly reduced
palatability, silage with 30 pounds of urea was eaten in
slightly smaller amounts. Urea is broken down to am-
monia. Cattle avoided silage containing 50 pounds of
urea per ton until free ammonia had volatilized from it.
9. Of six antibiotics tested, procaine penicillin and zinc
bacitracin appeared to give desirable results. Additional
experimentation may be needed before antibiotic addi-
tives may be found practical.
10. Grains respire less in silage than in dry storage, and
only hard-coated seeds were viable from the manure later.
Less whole grains from silage passed through the diges-
tive tract of cattle than when fed in dry form. Little
change in composition was noted after such passage.
11. Dry matter is digested as efficiently from silages as from
the same crop as hay.
12. Sugarcane is used more efficiently when freshly chopped
or as chopped fodder than as silage.
ACKNOWLEDGEMENTS
Drs. A. L. Shealy and E. L. Fouts were chairmen of the Animal Hus-
bandry and Dairy Science Departments, respectively, when many of the
silage investigations were conducted. Henry Zeigler and A. L. Sanchez
produced forages used in the silos from 1929 and 1949. E. I. DuPont de
Nemours Company contributed urea for sorghum silage in 1943-1945.
Drs. G. K. Davis and C. L. Comar cooperated particularly with urea as a
silage additive. Analyses of these forages and silages were supervised 1)y
Drs. W. M. Neal, L. L. Ru-itf, and J.. T. McCall. H. L. Somers. J. K.
Warrington, and many other individuals aided with records of digestibility
and feeding trials. Sincere acknowledgements for their cooperation and
contributions are given to them. Figure 3A was used by Dr. J. M. Wing
as Figure 8-1 in "Dairy Cattle Malnagement." The Reinhold Publishing
Corporation granted permission to re-use this copyrighted picture.
LITERATURE CITED
1. A new dairy barn and silo. 1907. Fla. Agr. Exp. Sta. Ann. Rpt.
Page xv.
2. Archibald, J. G., and C. I. Gunness. 1945. Seepage losses from a silo.
J. Dairy Sci. 28:321-324.
3. Becker, C. A. 1956. Ensiling efficiency, densities, and methods of
preservation of several silages. Master of Science in Agriculture thesis.
Univ. of Fla.
4. Becker, R. B., P. T. D. Arnold, C. J. Wilcox, W. A. Krienke, L. E.
Mull, and E. L. Fouts. 1965. Subnormal milk-cause and correction.
Fla. Agr. Exp. Sta. Bull. 692.
5. Becker, R. B., P. T. D. Arnold, J. M. Wing, J. T. McCall, and G. K.
Davis. 1957. Crimped oats for dairy cattle. J. Dairy Sci. 40:1550-
1553.
6. Becker, R. B., G. K. Davis, W. G. Kirk, P. T. D. Arnold, and W. P.
Hayman. 1946. Citrus pulp silage. Fla. Agr. Exp. Sta. Bull. 423.
7. Becker, R. B., and W. D. Gallup. 1927. Utilization of grain in kafir
and cane silage by dairy cows. J. Agr. Res. 35:279-282. Okla. Agr.
Exp. Sta. Bull. 164.
10. Grains respire less in silage than in dry storage, and
only hard-coated seeds were viable from the manure later.
Less whole grains from silage passed through the diges-
tive tract of cattle than when fed in dry form. Little
change in composition was noted after such passage.
11. Dry matter is digested as efficiently from silages as from
the same crop as hay.
12. Sugarcane is used more efficiently when freshly chopped
or as chopped fodder than as silage.
ACKNOWLEDGEMENTS
Drs. A. L. Shealy and E. L. Fouts were chairmen of the Animal Hus-
bandry and Dairy Science Departments, respectively, when many of the
silage investigations were conducted. Henry Zeigler and A. L. Sanchez
produced forages used in the silos from 1929 and 1949. E. I. DuPont de
Nemours Company contributed urea for sorghum silage in 1943-1945.
Drs. G. K. Davis and C. L. Comar cooperated particularly with urea as a
silage additive. Analyses of these forages and silages were supervised 1)y
Drs. W. M. Neal, L. L. Ru-itf, and J.. T. McCall. H. L. Somers. J. K.
Warrington, and many other individuals aided with records of digestibility
and feeding trials. Sincere acknowledgements for their cooperation and
contributions are given to them. Figure 3A was used by Dr. J. M. Wing
as Figure 8-1 in "Dairy Cattle Malnagement." The Reinhold Publishing
Corporation granted permission to re-use this copyrighted picture.
LITERATURE CITED
1. A new dairy barn and silo. 1907. Fla. Agr. Exp. Sta. Ann. Rpt.
Page xv.
2. Archibald, J. G., and C. I. Gunness. 1945. Seepage losses from a silo.
J. Dairy Sci. 28:321-324.
3. Becker, C. A. 1956. Ensiling efficiency, densities, and methods of
preservation of several silages. Master of Science in Agriculture thesis.
Univ. of Fla.
4. Becker, R. B., P. T. D. Arnold, C. J. Wilcox, W. A. Krienke, L. E.
Mull, and E. L. Fouts. 1965. Subnormal milk-cause and correction.
Fla. Agr. Exp. Sta. Bull. 692.
5. Becker, R. B., P. T. D. Arnold, J. M. Wing, J. T. McCall, and G. K.
Davis. 1957. Crimped oats for dairy cattle. J. Dairy Sci. 40:1550-
1553.
6. Becker, R. B., G. K. Davis, W. G. Kirk, P. T. D. Arnold, and W. P.
Hayman. 1946. Citrus pulp silage. Fla. Agr. Exp. Sta. Bull. 423.
7. Becker, R. B., and W. D. Gallup. 1927. Utilization of grain in kafir
and cane silage by dairy cows. J. Agr. Res. 35:279-282. Okla. Agr.
Exp. Sta. Bull. 164.
8. Becker, R. B., and W. D. Gallup. 1929. Grain losses in feeding corn
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9. Becker, R. B., W. M. Neal, C. R. Dawson, and P. T. D. Arnold. 1932.
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12. Browning, C. B., and J. W. Lusk. 1967. Effect of stage of maturity
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