Subject: SILAGES FROM TROPICAL FORAGES: NUTRITIONAL QUALITY AND MILK PRODUCTION
Aminah A., Abu Bakar C. and Izham A.
MARDI, Malaysia
E-mail: aminahal@mardi.my
Introduction
There is a need for silage making technology under local
conditions, especially in those areas experiencing drier months or
where monsoonal conditions restrict the routine cutting of forages. The
need for silage making is even more significant in dairy cattle
feeding, where the demand for uniform and high quality feed is of great
importance. The tedious daily harvesting of green forages throughout
the year also posed problems with smallholders, particulary when family
labour is not sufficient.
The objective of this paper is to evaluate the performance and
suitability of six tropical grasses and three forage crop for silage
making and a feeding trial for milk production.
Methods
Six grasses viz. setaria (Setaria sphacelata var. splendida),
signal (Brachiaria decumbens), humidicola (B.humidicola), MARDI Digit
(Digitaria setivalva), Napier (Pennisetum purpureum) and three crops
viz. (Zea mays) forage sorghum (Sorghum vulgare x S. bicolor) and S.
almum were planted. The grasses were cut at 6 weekly intervals. Corn
was harvested at 75 days, forage sorghum at 70 days and S. almum at 63
days after planting.
Fresh samples were taken for DM% and water-soluble carbohydrates
(WSC) (Dubois et al. 1956) and for silage making in the laboratory.
The silage samples were analysed for pH, lactic acid analysis (MAFF
1973) and physical characteristics. In the second experiment, six
multi-parous Sahiwal-Friesian cows in mid-lactation were used to test
three dietary treatments in a double switch over experiment (Cochran et
al. 1941). Treatments were levels of silage in the diet in direct
substitution for cut fodder as follows a) fodder ad libitum, b)
fodder+silage (50:50) ad libitum and c) silage ad libitum. In addition
each animal received six kg of concentrate once daily. Feed samples
were taken once weekly and composited by cow-period. Feed intake and
milk production were recorded daily.
Results and Discussion
The mean value of the WSC and the DM% in the crops and quality of
silage produced (pH and lactic acid content) are shown in Table 1. Corn
and forage sorghum produced good silage with pH <4.0 and lactic acid
level with the values of 2.72 and 3.7%, respectively (Table 1). For
the grasses, it was found that without additives, setaria and Napier
can be turned into acceptable silage with pH of 4.07 and 3.96,
respectively. The pH of the grass silage was reduced with the addition
of 4% molasses (Table 1).
The nutritional composition of sorghum silage and guinea grass used
in the second experiment are shown in Table 2. Treatment means for feed
DMI, milk yield and feed efficiency are in Table 3. Intake of DM from
roughage was higher (P<0.05) on treatment B than either A or C. The
higher roughage intake of treatment B appears to be attributable to a
stimulatory effect of silage on intake. The difference in the total
DMI reflects differences in roughage DMI. Expressed as percent body
weight, total DMI on the respective treatments were within the range
2.0 to 2.4%. Average daily milk yield was higher (P<0.5) for cows fed
sorghum silage compared with control. The difference in milk yield was
13% between treatments C and A. Mean feed efficiency value of cows on
the silage-based diet was nearly twice as good as either treatment B or
the control group A (Table 3).
Of the crops, forage sorghum and corn can be made into excellent
silage without additives. Grasses are suggested to be cut at about 6
weeks regrowth. Napier and setaria can be ensiled into reasonable
silage, but the quality can be improved with the addition of 4%
molasses before ensiling. As for the second experiment, sorghum silage
appears to be a better feed than the average guinea grass commonly fed
to lactating cows in this country. This is reflected in its effect on
milk yield and feed efficiency.
Table 1. Silage Made from Tropical Grasses and Forage Crops
======================================================================
Crop Species Silage Silage 4 % Quality
molasses
----------- ------------- --------------------------
DM% WSC pH lactic pH lactic
% acid (%) acid (%)
----------------------------------------------------------------------
Grasses
S. splendida 15.30 6.17 4.07 2.47 Good 3.64 1.96
B. decumbens 20.37 8.64 5.07 1.08 Poor 3.37 1.87
B. humidicola 20.85 2.35 5.32 1.26 Poor 3.31 2.03
D. setivalva 18.21 1.26 4.32 1.46 Poor 3.31 2.83
P. purpureum 15.77 9.88 3.96 2.53 Good 2.98 nd
P. maximum 19.35 3.03 4.71 1.84 Moderate 3.27 2.74
Crops
Z. mays 21.20 22.99 3.72 2.72 Very good
S. vulgare x 21.35 11.69 3.68 3.75 Very good
S. bicolor
S. almum 18.40 nd 4.40 nd Moderate
----------------------------------------------------------------------
nd: not done
Table 2. Chemical composition of feedstuffs (%)
======================================================================
Feedstuff DM CP TDN CF EE NFE Ash Ca P
----------------------------------------------------------------------
Guinea grass 24.1 11.7 61.6 33.6 2.4 46.1 6.2 0.57 0.27
Sorghum silage 29.4 8.7 60.1 33.4 2.6 51.0 4.2 0.47 0.17
Concentrate 91.2 23.5 77.2 5.5 11.6 54.7 4.7 0.57 0.36
----------------------------------------------------------------------
Table 3. Feed intake and efficiency and milk yield for the different
treatments
======================================================================
Variables A B C
----------------------------------------------------------------------
Feed DM Intake (kg/d)
Roughage 4.95b 6.22a 4.50b
Concentrate 5.40 5.40 5.40
Total 10.35b 11.63a 9.90b
DMI Per 100 kg BW 2.1 2.4 2.0
Milk Yield (kg/d) 7.01c 7.54ab 7.93a
Feed Efficiency (kg total DMI/kg milk) 2.16b 2.65b 1.37a
----------------------------------------------------------------------
The values within rows with different letters are significantly
different (P<0.05)
References
Dubois, M., Gilles, K.A., Hamilton, J.K., Rebers, P.A. and Smith, F.
(1956). Calorimetric method for determination of sugars and related
substances. Anal. Chem. 28(3):350-356.
MAFF (1973). The determination of lactic acid in silage juice. Manual
of Analytical Methods. Technical Bulletin 27, Ministry of
Agriculture and Food, United Kingdom.
Cochran, W.G., K. M. Autrey and C.Y. Cannon. (1941). A double change-
over design for dairy cattle feeding experiments. J. Dairy Sci.
24:937-951.
POSTER: Silage quality and losses due to ensiling of Napier grass,
Columbus grass and maize stover under small holder conditions in Kenya
P.J.M. Snijders and A.P. Wouters
E-mail: p.j.m.snijders@pr.agro.nl
Introduction
On behalf of the National Dairy Development Project, several
ensiling experiments were conducted at the National Animal Husbandry
Research Centre (NAHRC) at Naivasha, Kenya, in the period 1983-1989.
The aim of the experiments was to develop methods and techniques
suitable for smallholders for the ensiling of Napier grass, Columbus
grass and maize stover to overcome feed shortages during the dry
season.
Materials and methods
The following six series of ensilage experiments were conducted:
Series A: 2 silages of chopped, wilted Napier grass with or without
addition of molasses, ensiled in an number of netted nylon
bags and placed inside a larger silage clamp
Series B: 6 pits of wet long or chopped Napier grass with addition of
3.5% or 6% or without molasses
Series C: 4 pits of wet long or chopped Napier grass with addition of
3.5% molasses or MUM (molasses/urea mixture)
Series D: 6 pits of wet long or chopped Napier grass with addition of
3% molasses
Series E: 4 pits of wet long or chopped Columbus grass with addition of
3% molasses
Series F: 3 pits of chopped maize stover or maize stover mixed with
lablab, without additive.
Silages were made in small earthen pits in quantities varying from
1000 to 2000 kg fresh material, thus more or less representing
conditions for small-scale farmers. Sides and top of the pit were
covered with 2 m wide polyethylene plastic sheets covered with a layer
of about 50 cm of sand on top and sides
Results
Percentage non-edible silage (mouldy and rotten silage) varied from
0 to 2.5%, indicating that sealing with polyethylene sheet and soil
cover was good. Levels of butyric acid and contents of ammonia nitrogen
often were below 0.3% and 12 respectively for silages of wilted Napier
grass and wet chopped Columbus grass with the addition of molasses and
for silage of maize stover. These fermentation characteristics indicate
good silage quality. Smell was good as well. For some wet Napier grass
silage and for silages made with addition of MUM of unchopped Columbus
grass, results were less good.
Long, unchopped Napier grass wilted for one or two days to about
30% dry mater and with the addition of molasses and with proper
compaction, often resulted in good silage as well.
Dry matter losses due to ensiling of Napier grass averaged 15.2
4.2%. Losses were lower for silages made of grass wilted for one or two
days and higher for silages made of wet unchopped grass and grass with
the addition of MUM. For wet Columbus grass, there was also a clear
positive effect of chopping. Average dry matter losses for ensiled
maize stover were 8.1%.
Losses of crude protein averaged 16.9%, but variation was large,
partly due to sampling errors. Losses were lower for wilted silages and
much higher for silages with the addition of MUM.
In vitro organic matter digestibility decreased due to ensiling and
was more than 10 units lower in case of poor quality silages. For well-
preserved silages, the decrease in digestibility was often limited to 5
units or less. Losses of digestible organic matter for Napier silages
averaged 28.57.9%. Losses were lower for wilted silages and much higher
for wet silages of series D and silages made with the addition of MUM.
Results show that under smallholders' conditions, good silage can
be made. Poor quality silages of poorly digestible Napier grass
however, will not meet maintenance requirements of animals.
Conclusions and practical recommendations
1. Under small farmer's conditions, good silage can be made, provided
that air-tight sealing with plastic polyethylene sheets is applied,
with at least a cover of 50 cm of soil on top and sides of the pit,
and with good drainage of rain water. Ensiling and covering has to be
completed within one day.
2. As shown by good fermentation characteristics and smell, wilting one
or two days to reach a dry matter content of 30% often results in
good silage, especially when molasses is added. Wilting to a dry
matter content of more than 30%, or wilting of old stemmy material is
not recommended, because of the higher weather risks and difficulties
with compaction.
3. Dry matter losses due to ensiling of wilted or wet, chopped Napier
grass with the addition of molasses could be limited to 15%.
4. Dry matter losses of silages made of wilted, un-chopped long Napier
grass are probably slightly higher than from chopped Napier grass.
Provided proper compaction, addition of molasses, air-tight sealing
and covering with at least 50 cm soil, making silage of long, wilted
Napier grass may be a good alternative for smallholder conditions.
5. Although it is not very clear from the limited experience provided
by these experiments, addition of 3% molasses to wet and long wilted
Napier grass will probably be sufficient to obtain good quality
silage, especially when hand-mixed through chopped silage. To
increase chances for good quality silages addition rates of up to 6%
are suggested when molasses is applied in the silage pit on layers of
grass. For chopped, wilted Napier grass and for chopped Columbus
grass, addition of molasses can be lower.
6. MUM as an alternative additive for molasses does not produce good
silages.
7. Silages of chopped Columbus grass with molasses and chopped maize
stover without molasses made good silage. Dry matter losses appeared
to be lower compared to Napier grass.
8. Because of a higher risk for leaching, dilution of molasses with
water in order to ease application should not exceed a 1-to-1 ratio.
A relatively small quantity of molasses should be used at the bottom
layers of the pit, and more to be added to the middle and top layers.
9. Losses of crude protein and digestible organic matter were not
accurately measured in these experiments, because of the limited
number of samples and because of sampling errors. Based on good
quality silages in these experiments, losses are about 15% and 25%
for crude protein and digestible organic matter respectively.
10. Poor silages of overgrown Napier grass will at best supply
sufficient energy for maintenance. Feeding overgrown Napier grass as
standing hay, or mulching might be a better alternative then. Proper
storage and utilisation of crop residues like maize stover and
preserving feeds like sweet potato vines, fodder beets, cassava or
fodder trees may prove better in those situations.
POSTER: Wet Season Silage Production at Taminmin High School
Chris Regan
Northern Territory Department of Primary Industry
and Fisheries (NT DPIF), Darwin, Australia
E-mail: Chris.Regan@DPIF.nt.gov.au
1. Feed Resources in the Wet Tropics
The main limiting factor for ruminant production in the Tropical
Top End of Australia is the lack of good quality feed throughout the
year. Seasonal rainfall provides a period of abundant herbage at its
peak nutritional value during the wet season, followed by a period of
lower quality mature herbage in the dry season. It makes sense to try
and conserve the abundance of good quality vegetation when it is
available in the wet, and use it later in the dry season when plant
growth is severely restricted, natural feed is in short supply, and
commercially available feed is relatively expensive.
This is exactly what has been done at Taminmin High School, which
is located near Humpty Doo, approximately 40 km South East of Darwin,
Northern Territory, Australia. The precise location is 12° 24' S, 131°
15' E.
2. Taminmin's Silage Program
As a regular part of their farm management strategy, Taminmin makes
baled silage during late January or early February each year. Making
hay at this time is not an option because it is too difficult to dry
the plant matter to the required 85%DM or more.
Fig 1. Baled Silage being transported on the Taminmin Trailer
[Figure 1 available in PDF and HTM files]
On the other hand, wet season pasture can be baled at lower dry
matter (DM) content and higher moisture than hay, wrapped in plastic
film and allowed to ferment into silage.
Almost any pasture can be made into silage, but the best silage is
made from the best pasture. At Taminmin, silage is regularly made from
Pangola grass, Cavalcade legume, and Wynn Cassia legume.
The trick is to watch the weather, then cut only enough pasture
that you can comfortably wilt, bale, wrap and stack in a single day
without any rainfall.
3. A Typical Day of Making Silage
As long as we are confident of getting a rain free day we go ahead.
Trial and error has taught us to process no more than 1.5 hectares.
Check with the Weather Bureau. They regularly track tropical storms
by radar and are very competent predictors of storm incidence, arrival
times, and intensity/duration. We have found their accuracy decreases
as distance inland increases, but for the cost of a phone call they are
a terrific advisory service.
Pasture is cut at 0900 hours. Sunrise is usually just after 0700,
and the two hours is enough time to get most of the free water
evaporated from the pasture.
A second tractor forms up the windrows almost immediately. This is
usually done by 10.30. We turn the windrows over just once, starting at
11.00. This is usually done by 12.30. We sample the windrows and
estimate the dry DM content. This is easily done in 10 mins using a
microwave oven, but we are lucky enough to have a probe (Farmscan 2180)
to do this in the field. We start baling as soon as the DM content is
40% or more. (Actually, the last two seasons the contractor has made
this process much more efficient: he has used a mower/conditioner to
cut, condition, and windrow in one operation. This has also allowed the
cut pasture to dry out quicker.)
We get about 60 bales, and baling is normally finished by 1730. We
start wrapping as soon as the bales are formed. This takes longer than
baling, but is completed just before 1900.
We do not provide any additives such as molasses, urea, or lactic
acid bacteria inoculant. Our research has shown that the cost of the
additive cannot be justified. Weight increases of stock being fed
silage with or without additives are not significantly different.
However, it is extremely important to wilt the material to about 40%DM
before baling. Ensiling wet material (e.g. less than 30% DM) will
almost certainly result in production of poor quality silage, high
amounts of wastage, and a high degree of stock rejection.
It is a very busy day that we usually repeat, weather permitting,
two or three times in 7-10 days. The end result is a harvest of between
70-80 tonnes of reasonable quality feed stored away for use later in
the dry season.
After baling, we spread fertiliser. Late wet season rains give us a
good regrowth which can be grazed or harvested a second time. The
second harvest is usually made into hay as per normal practice for our
area.
4. The Benefits
* Fodder conservation from our improved pastures has increased by more
than 40%.
* We get two harvests instead of one (and a grazing period).
* The same small areas previously were only lightly grazed and turned
into hay during May: although it was good quality hay, it is
nutritionally lower than the silage made in February.
* Weed control is improved. Small amounts of weed that are present are
ensiled before they head out. Consequently we spend less time and
money on weed control, whilst continually giving our pastures a
competitive advantage.
* The process manages Wynn Cassia really well. Wynn Cassia makes good
silage, but very poor hay (see section below).
* Our feed costs during the dry season are dramatically reduced. We
still buy supplements, but the vast bulk of the feed is provided by
the conserved silage.
* Conserved forage is a cash crop: we have always sold our excess hay,
but also having baled silage for sale improves our management options
as well as our annual income.
5. The Disadvantage
The major difficulty with the program is the need to use a
contractor. The making of silage is not difficult, but the program
depends on having the equipment readily available. Although late
January / early February is a time of inactivity for baling
contractors, most do not have wrapping machines, and anyhow it is
costly to move the equipment about in order to process a relatively
small amount of forage.
Hopefully, as more people try this management strategy, costs will
reduce, and efficiencies due to processing larger amounts of forages
can improve.
6. Special Benefit: Wynn Cassia
This vigorously growing tropical legume has a positive benefit for
soil nitrogen content, and is an excellent ground cover for weed
control. However,
* cattle and buffalo only eat Wynn Cassia reluctantly under normal
grazing conditions, and
* it is extremely difficult to make into hay. This is because the plant
is very leafy. The leaves shatter easily as they dry out. They also
shatter and drop off when moving through a baler. If you are
successful at all in making a bale of Wynn Cassia hay, it will be
nearly all stem.
The positive benefit is that Wynn Cassia silage is easy to make:
the higher moisture leaves do not shatter, and the bale is much easier
to form. Silage made from a mixed Wynn Cassia / grass pasture is even
easier to make, and usually better quality. Secondly, stock love Wynn
Cassia silage: they accept it immediately, and eat it all when it is
presented.
7. For the Technically Minded
A summary for the silage quality, including nutrition data is shown
in the table.
Table 1. Harvest Summary: Baled Silage
-----------------------------------------------------------------------
Pangola Cavalcade Wynn Cassia
-----------------------------------------------------------------------
Dry Matter (%) 42 45 52
Digestibility (%DM) 57 55 58
Metabolisable Energy
(MJ kg^-1DM) 8.5 9.0 8.8
Crude Protein (%DM) 9.1 13.5 12.0
Mean Bale Weight (kg) 383 430 390
No Bales Produced 57 75 45
Estimated total
DM conserved (kg) 9169 14513 9126
Productivity
tonnes DM ha^-1) 6.1 7.3 6.1
-----------------------------------------------------------------------
Total fresh: 71.6 tonnes Total DM: 32.8 tonnes