JOURNAL OF THE SCIENTIFIC AGRICULTURAL SOCIETY OF FINLAND
Maataloustieteellinen A ikakauskirja

229

Vol. 51:229-237, 1979

Maize for silage
I. Conservation of whole maize plant for silage with treatment

of preservatives and urea before ensiling

Setälä, J.1), Seppälä, J. 1), Pulli, S. 2 ) and Poutiainen, E. 1)

x ) Department of Animal Husbandry, University of Helsinki, 00710 Helsinki 71
2 ) Department of Plant Husbandry, University of Helsinki, 00710 Helsinki 71

Abstract. Maize was harvested with a precision chopper and ensiled in five plastic
tower silos, 1 500 kg fodder/silo. The silages and the ensiling methods were: 0.5 %

urea per fresh weight (A), 1.0 % urea per fresh weight -(- Viher-acid 4 1/1 000 kg of
silage (B), 0.5 % urea per fresh weight + Viher-acid 4 1/1 000 kg of silage (C). Viher-
acid 4 1/1 000 kg of silage (D) and silage without urea or preservatives (E).

The dry matter content of the whole maize was 21 % and the crude protein content
was 10.8 % in DM. The addition of urea increased the crude protein (N x 6.25) content
in A- and C-silages to 17.7 percent and in B-silage to 24.9 percent.

The quality of the silages was good, and some marks of butyric acid was found only
in the silage ensiled without Viher-acid or urea. The addition of Viher-acid lowered
the fermentation rate so that the sugar content of the corresponding silages was higher.
The sugar content was higher (P < 0.01) and the content of lactic acid lower (P < 0.001)
in the silage ensiled only with Viher-acid.
Urea increased the content of lactic acid and the content of acetic acid of the
silages. In the silages ensiled with urea the use of Viher-acid tended to lower the
fermentation rate.

The use of urea increased the NH 3-N (P < 0.05) and the soluble N contents
(P < 0.001) in the silages. In spite of the low dry matter content of the silages some
enrichment of the urea in the lower parts of the silos was only found in the silage
ensiled with 1 % of urea (P > 0.05) and Yiher-acid. This was due to the larger
effluent amount from the silo.

The fermentation losses of dry matter were smallest in the silage D (3.9 %) and
highest in the silage E (11.6 %) (P < 0.05). The losses in A-, B- and C-silages were
7.6 %, 4.7 % and 9.2 %, respectively. The use of urea decreased the fermentation
losses.

Introduction
Because of the rich content of soluble sugars maize could be ensiled without

preservatives. In spite of careful ensiling an intense secondary fermentation
was found in sorghum, corn and corn stover silages (Setälä et al. 1979).

According to Morvarid et al. (1973) and Woolford et al. (1978) secondary
fermentation is caused by the great number of yeasts and moulds, which are

https://www.c-info.fi/en/info/?token=Za59nj0d_jHc8ral.4HA4BLht1YxyI2P3mG1Jgw.JXKFrLqQcv1iGnZLnpK4OsJbC1aXPIWrJuTrMp2POIOYJi5yu4s5Zigt5ZcEchrdaID5WO75jakEojBEbPdYmxNqAKUxiwzKw7UjEvkrWUWbkFuXzVOUxnIYJcnnlpnRUhKfZD5_c-Iz2xPEWwfUT9oW4TwYUvZ6Xpsnx13Y9BqDmmTun_pGYOIwwKoHcGdPtBB1nN1R9eJfqsACwh33qmCs-cNKgz9qw6PNaqZ2EYWpSD_4eThJbA


230

typical for maize and sorghum plants. The low dry matter content and the
high sugar content form a favourable base for the growth and function of the
micro-organisms.

Because of the low content of crude protein in the feeding of ruminants
maize silage must be supplemented by some N-source. In this respect urea
can be used providing that it is added to the silage before ensiling (Huber
et al. 1968).

in this trial were studied the quality and composition of the silages treated
with acid preservatives and urea before ensiling.

Materials and methods
Maize was harvested with a precision chopper and ensiled in plastic tower

silos (2.7 m 3). The dry matter content of the raw material was about 21
percent. Exactly 1 500 kg of fresh fodder mass was ensiled in each silo ac-
cording to an experimental design shown in Table 1. The pressure used was
400 kg/m 2 .

The preservative used was a mixture of sulphuric acid, formic acid and
formaldehyde (»Viher-acid»). The preservative and urea were added to the
fodder in a water solution after each 50 kg of fodder mass ensiled in the towers.
The total amounts were 4 litres acid mixture and 500—1 000 grams urea/
1 000 kg of silage.

Fermentation losses were determined by subtracting the amounts of the
silage and the effluent from the amounts of the fodder ensiled in the tower
silos. The additions of water solutions when Viher-acid and urea were added
to the silages were also considered in the calculations. The amounts of so-
lutions added were about 30, 100, 70 and 50 litres in A-, B, C- and D-silos,
respectively.

The samples for the analyses of the raw materials and of the silages were
taken from every 50 kilogram lots. In addition to drying the samples in vacuum
at +6o° C for two days, 100—150 grams of silage was frozen for the quality
analyses.

Table 1. Experimental design, crops and their ensiling.

Silages
A B C D E

Fodder kg/ tower silo 1 500 1 500 1 500 1 500 1 500
Urea, % of the wet weight 0.5 1.0 0.5
Acid mixture,* 1/1 000 kg of fodder 4.0 4.0 4.0

* Viher-acid: 45 % sulphuric acid, 20 % formic acid, 10 % formaldehyde.

The analycital methods used were those described by Setälä et ai. (1979).
Urea was determined colorimetrically (Anon. 1973).

The results were tested statistically by analysis of variance. The sig-
nificances of the differences between individual means were tested with
Tukey’s procedure.



231

Results and discussion

The chemical composition of the raw material and the silages
The dry matter content of the present material was only 21 percent and the

grains in the cobs were near milk stage. This growth stage is considered early
for making corn silage, because there is always a danger of a faulty fermen-
tation producing acetic acid and alcohols and because the fermentation losses
could be very high (Nehring and Hoffmann 1960, Becker and Nehring

1969, Giardini et al. 1976). However, silage of fairly good quality can be
made also at this growth stage (Setälä et al. 1979).

The amounts of sugars and crude protein in raw materials were 16—17 %

and 10.5—11.0 % in dry matter, respectively (Table 2). The addition of urea
increased the crude protein content 6.5 %-units when 0.5 % of urea in silage
fresh weight was included, and 11.3 %-units when 1 % of urea was used.

The sugar content decreased significantly (P < 0.01) in silages ensiled
with urea, urea + Viher-acid and without preservatives. The silage ensiled
only with Viher-acid had the highest content of sugars and there was no
statistical difference (P > 0.01) in the sugar content between the raw material
and this silage.

The content of sugars in silages reflects the strength of the fermentation.
In corn silage the fermentation takes place mostly during the first ten days
after ensiling. After that the fermentation is finished if no secondary fer-
mentation takes place (Schaadt and Johnson 1969, Britt and Huber 1975).

The quality and the fermentation losses of the silages
The quality of all silages was good as judged by colour, odour and analyses

(Table 3). The pH values were very low in all silages.
The use of acid preservative decreased the fermentation in the silages (also

Gross and Beck 1970). The content of lactic acid was significantly (P < 0.001)
higher in silages which were ensiled without acid supplement (also Britt et al.
1975). The same trend could also be seen in the content of acetic acid (Fig. 1).

The use of urea increased the content of lactic acid and the content of
acetic acid in the silages, although the changes were not significant (P > 0.05).
Changes of this kind after addition of urea before ensiling have been noted
also by Gross et al. (1969) and Shirley et al. (1972).

Urea is hydrolyzed to NH 3 during ensiling. The rate of hydrolysis is the
more vigorous the lower is the dry matter content of the silage (Polan et al.
1967). In spite of differences in the contents of organic acids no statistical
differences were found in the pH values of the silages. Ammonia is a strong
buffer and affects the pH values so that more organic acids are needed to lower
the pH to the desired level (Shirley et al. 1972).

The addition of urea increased the content of NH 3-N and soluble N in the
silage (Fig. 2). The content of NH 3-N is higher (P < 0.05) in A-silage com-
pared to C-silage, which was supplemented also with Viher-acid. It is possible
that the use of preservatives prevents the degradation of urea to NH 3 and the
ammonia exists in the form of NH4

+-ion.



232

Table
2.

Chemical
composition
of
raw

material
and
silages.

Silages

Raw
material

A

B

C

D

E

P
<

0.01

x

s
-d*

x

s.d.

x

s.d.

x

s.d.

x

s.d.

x

s.d.

Dry
matter,
%

20.9
0.26

19.3
0.36

19.4
0.41

19.1
0.87

19.2
0.32

19
0

0
95

ns

%

in
DM

Ash

6.7

0.35

6.5

0.41

6.9
0.24

7.3
0.58

7.1

0.22

6.5

0.71

ns.

Crude
protein

10.7
0.20

17.7
0.80

24.9
2.32

17.7
0,99

11.3
0.38

11.3
0.35

R*-A,
B,
C

A-B,
D,
E

Crude
fibre

24.8
0.78

26.3
0.86

26.8
1.33

26.6
0.84

26.0
1.49

26.7
1.34

ns.

Ether
extract
1.3

0.10

1.8

0.24

1.5

0.06

1.4
0.07

1.4
0.08

1.6

0.10

R*-A,
E,

A-B,
C,
D,
E

D-E

N-free
extracts
56.3

1.31

47.6
1.46

39.8
2.85

46.7
1.95

54.3
1.81

53.7
1.51

R*-A,
B,
C

B-A,
C

Su
S
ars

16.10
1.09

8.6

1.44

11.2
2.93

10.9
1.21

14.2
0.52

10.4
1.06

R*-A,
B,
C,
E

D-A,
B,
C.
E

R*
=

rawmaterial
A

=

0.5
%

urea,
no

Viher-acid
B

=

1.0
%

urea,
Viher-acid

C

=

0.5
%

urea,Viher-acid
D

=

Viher-acid
E

=

no
preservatives



233

Table
3.

Quality
of
corn
silages
ensiled
without

preservatives,
with

Viher-acid
and

different
amounts
of

urea.

Silages

A

B

C

D

E

x

s.d.

x

s.d.

x

s.d.

x

s.d.

x

s.d.

P
<

0.001

P
<

0.05

Dry
matter,
%

....

19.3
0.37

19.4
0.41

19.1
0.87

19.2
0.32

19.0
0.95

-
ns.

pH

3.6

-3.6-3.6

3.5-3.6--
ns.

%

in
DM

Lactic
acid

7.98
0.98

4.58
0.63

4.28
0.93

2.98
0.15

7.88
1.08

A-B,
C,
D

E-B,
C,
D

D-A,
B,
E

Acetic
acid

0.83
0.07

0.46
0.07

0.45
0.14

0.58
0.18

0.73
0.14

A-B,
C

E-B,
C

Propionic
acid

0.32
0.06

0.31
0.09

0.29
0.12

0.46
0.05

0.31
0.05

ns.

Butyric
acid

0.10

NH3
-N

0.11
0.01

0.14
0.08

0.08
0.01

0.07
0.01

0.08
0.01

-
A-C,
D,
E

B-A,
C,
D,
E

Soluble
N

1.85
0.09

2.88
0.18

1.77
0.10

0.79
0.08

0.79
0.12

A-B,
D,
E

C-B,
D,
E

B-D,
E

A

—E
see

Table
2.

V,



234

Some signs of the butyric acid was found in the silage ensiled without
preservatives or urea. This is quite unusual for the corn silage (Andrieu
1976) and has not been stated earlier (Setälä et ai. 1979).

The fermentation losses in dry matter were smallest (P < 0.05) in the
silage ensiled with Viher-acid and greatest (P < 0.05) in the silage ensiled
without any additives. (Table 4). The corresponding losses were 3.9 % and
11.6 %. In the A, B and C silages the fermentation losses were 7.6 %, 4.7 %

and 9.2 %, respectively. It seems that urea had lowered the fermentation
losses during ensiling (also Gross etal. 1969).

The urea concentration of the silages in different parts of the silos
In spite of the low dry matter contents particularly urea-rich layers were

not found in the silages (Fig. 3). This can be explained by the small effluent
amounts flowed from the silos (Table 4). Urea can be easily dissolved in the
effluent and then be concentrated in the bottom layers of the fodder in a tower
silo. Because of this it has been advised to add urea before ensiling only when
the dry matter content of the fodder is over 25 percent (Böttger 1969, Kirch-
gessner 1973).

Figure 1. The contents of lactic and
acetic acids in the silages. A—E
see Table 1.



235

Table 4. The amounts of effluents per 1 500 kg fodder, soluble N content of the effluents and

the fermentation losses in dry matter of the corn silages.

Silages
A B C D E P < 0.05 P < 0.001

Silage effluent, kg 1.6 56.0 19.0 1.0 - C-A, D, E B-A, C, D, E
Soluble N, %in effluent 1.10 4.30 2.10 0.94 - C-A, D. E B-A, C, D, E
Fermentation losses in DM,
%in raw material 7.6 4.7 9.2 3.9 11.6 D—A, B, C, E

E-A, B, C

Because of the greater effluent amount from the B-silage, urea concentration
was slightly higher in samples taken after 180 fermentation days from the
bottom of the silo (Fig. 3). However, the increase was not statistically signifi-
cant (P > 0.05). The greater amounts of effluents in C- and especially in
B-silages could be partly explained by the fact that both urea and Viher-acid

Figure 2. The contents of NH 3-N
and soluble N of the silages. A—E
see Table 1.



236

were added to the silages in water solutions. The amounts of the solutions
were about 100 and 70 litres in the silages of B and C, respectively.

The soluble N content was highest (P < 0.001) in the effluent of the silage
ensiled with 1 % of urea. The losses of urea in the form of soluble N were,
however, quite small. The average urea contents (% in silage DM) were in
A-, B- and C-silages 2.4 % (s.d. 0.30), 3.9 % (s.d. 0.67) and 2.2 % (s.d. 0.63)
and the highest contents found were 2.9, 4.8, and 2.8 %, respectively.

The use of the greatest amount of urea (1 % per fodder fresh weight) could
be too high in practise, if the silage is going to be used for a long time. More-
over the use of 0.5 % of urea already raises the crude protein content of the
corn silage at the same level with an ordinary grass silage.

REFERENCES

Andrieu, J. 1976. Factors influencing the composition and nutritive value of the ensiled
whole-crop maize. Anim. Feed. Sci. Technol. 1: 381 392.

Anon. 1973. The determination of urea in feeding stuffs. Ministry of Agriculture, Fisheries
and Food. Tech. Bull. 27.

Becker, M. & Nehring, K. 1969. Handbuch der Futtermittel I. p. 296 305. Hamburg.
Britt, D. G. & Huber, J. T. 1975. Fungal growth during fermentation and refermentation

of non-protein nitrogen treated corn silage. J. Dairy Sci. 58 (11): 1667 1671.
, Huber, J. X. & Rogers, A. L. 1975. Fungal growth and acid production during
fermentation and refermentation of organic acid treated corn silages. J. Dairy Sci.
58(4): 532-539.

Böttger, C. 1969. Harnstoff zur Eiweisserganzung im Maissilage. Mitt. DLG. 35: 1083 1086.
Giardini, A., Gaspari, F., Vechiettini, M. & Schenoni, P. 1976. Effect of maize silage

harvest stage on yield, plant composition and fermentation losses. Anim. Feed. Sci.
Xechnol. 1: 313-326.

Figure 3. The variability of the urea concentration in the silages ensiled
with urea. The samples are taken in the connection of emptying the silos
during 100 180 days after ensiling.



237

Gross, F., Koch, G. & Koller, G. 1969. Harnstoff im Maisgärfutter. Wirtschaftseigene
Futter 15: 210-227.
& Beck, T. 1970. Untersuchungen fiber die Hemmung von aeroben Abbauprozessen
durch Propionsäure bei der Auslagung von Gärfutter. Wirtschaftseigene Futter 16:
1-14.
& Riebe, M. 1974. Gärfutter. 283 p. Stutgart.

Huber, J. T,, Polan, C. E. & Hillman, D. 1968. Urea in high corn silage rations for dairy
cattle. J. Anim. Sci. 27; 220 226.

Kirchgessner, M. 1973. Tierernährung. 406 p. 2th Ed. Frankfurt am Main.
Morvarid, A., Koch, G. & Kirchgessner, M. 1973. Chemische und mikrobielle Veränderungen

instabiler Maissilagen. Wirtschaftseigene Futter 19: 5 14.
Nehring, K. & Hoffmann, M. 1960. Der Einfluss des Vegetationsstadrums auf die Gärverluste

bei der Maisensäuerung. Dt. Landw. 9: 441 —444.
Polan, C. E., Huber, J. T. & Miller, C. N. 1967. Recovery of nitrogen from urea treated

silage. Abstract. J. Dairy Sci. 50: 616.
Schaadt, H. Jr. & Johnson, R. R. 1969. Effect of ensiling time on distribution and losses

of nitrogen in corn silage treated with limestone and NPN. J. Anim. Sci. 29: 57 61.
Setälä, J., Seppälä, J., Pulli, S. & Poutiainen, E. 1979. Preliminary studies on the con-

servation of whole sorghum and corn plant and sugar corn stover for silage. J. Scient.
Agric. Soc. Finl. 51: 222-228.

Shirley, J. E., Brown, L. D., Thomas, F. R., Stroube, W. H. 1972. Influence of varying
amounts of urea on the fermentation pattern and nutritive value of corn silage. J.
Dairy Sci. 55: 805-810.

Woolford, M. K., Honig, J. & Fenlon, J. S. 1978. Mikrobiologische, physikalische und
chemische Veränderungen während der aeroben Abbaus von Maissilage. Wirtschafts-
eigene Futter 24: 125 139.

Ms received May 28, 1979.

SELOSTUS

Maissi säilörehun raaka-aineena I. Viherhapon ja urean käyttö maissisäilö-
rehun säilöntäaineena

Setälä, J., 1) Seppälä, J., 1 ) Pulli, S. 2) ja Poutiainen,E. 1)

*) Helsingin yliopiston kotieläintieteen laitos, 00710 Helsinki 71
2) Helsingin yliopiston kasvinviljelytieteen laitos, 00710 Helsinki 71

Maissia säilörehun raaka-aineena käsittelevän tutkimuksen ensimmäisessä osassa keski-
tyttiin säilönnällisten kysymysten selvittämiseen. Säilörehut tehtiin käyttämällä säilöntä-
aineena Farmoksen Viherhappoa sekä lisäämällä rehuihin ureaa 0.5 % tai 1.0 % rehun tuore-
painosta. Lisäksi valmistettiin painorehua ilman säilöntäaineita.

Vaikka säilörehut tehtiin hieman liian varhaisella kasvuasteella olevasta raaka-aineesta
(ka-% 21), rehut olivat hyvälaatuisia. Merkkejä voihappokäymisestä esiintyi vain paino-
rehussa. Säilöntäaineen käyttö alensi rehuissa tapahtuvaa käymistä ja käymistappioita. Käy-
minen oli kuitenkin voimakas kaikissa rehuissa ja säilörehujen pH oli hyvin alhainen.

Urean lisääminen rehuun nosti NH3 -typen ja liukoisen typen määrää säilörehussa. Koska
urea liukenee helposti puristenesteeseen, sitä saattaa kerääntyä haitallisia määriä alimpiin
rehukerroksiin. Kun ureaa käytettiin 1 % rehun tuorepainosta, urean kerääntymistähavait-
tiin, mutta se ei ollut tilastollisesti merkitsevää. Puristemehun merkitys kerrostumisriskiä
lisäävänä tekijänä tuli selvästi esille. Urean lisäys säilönnän yhteydessä pienensi käymistap-
pioita.