Cassava hay : A new strategic feed for ruminants during the dry season

Cassava hay: A new strategic feed for ruminants
Livestock Research for Rural Development
1997, Volume 9, Number 2
Cassava hay: A new strategic feed for ruminants during the dry
season

M Wanapat, O Pimpa, A Petlum and U Boontao

Department of Animal Science, Faculty of Agriculture
Khon Kaen University, Khon Kaen 40002, Thailand

Abstract
Dry season feeding is critical in terms of both quantity and quality especially for productive ruminants
such as dairy cattle. Cassava (Manihot esculenta, Crantz) a tuber crop can be grown as foliage in the dry
season producing first cut yield after three months of 20,40 kg/ha (fresh) or 10,200 kg/ha (dried) and
estimated combined yield of second and third cut of 40,820 kg/ha (fresh) or 20,400 kg/ha (dried) or 5,102
kg crude protein/ha. Cassava hay (CH) contained high level of crude protein (25%) and low levels of NDF
and ADF. Voluntary intake of CH was 3.1% of live weight and the dry matter digestibility was 71%.
Ruminal DM digestibility of CH was relatively high while protein ruminal degradability was low
indicating it would be a good source of bypass protein.
Key words: Cassava, hay, feed, dry season, ruminant, dairy cattle.

Introduction
Cassava or tapioca (Manihot esculenta, Crantz) is an annual tuber crop grown widely in the tropics and
sub-tropics. It can easily thrive in sandy-loam soil with low organic matter, receiving low rainfall and high
temperature. It is therefore a cash crop cultivated by small-holder farmers within the existing farming
systems in many countries. Cassava tuber contains high level of energy and minimal level of crude protein
and has been used well as readily fermentable energy in ruminant rations. However, cassava leaves
contain high level of crude protein (25%) some of which can apparently by-pass the rumen since it is in
the form of a tannin-protein complex (Wanapat 1995).
The objectives of this study were to assess the feasibility of using cassava whole crop as hay when
harvested in the dry season after 3 months of cultivation.

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Cassava hay: A new strategic feed for ruminants
Materials and Methods
Cassava cultivation and hay making
Cassava was grown in rows using stems as plant material. Sowing date was September and harvest was in
December (3 months) by picking the whole crop at 6 inches above the ground. Fresh yield was measured
immediately and the biomass was left in the field to be dried for 3 days before being collected. The dried
cassava biomass can either be stored in a stack or made into a bale for later storage and feeding. Cassava
hay can easily be prepared in a simple square-wooden-box to obtain a 15-kg bale. A finished bale is
recommended to be further sun-dried to secure dry matter of at least 85-90% and to reduce hydro-cyanic
acid content.
Nutritional evaluation
Cassava hay was fed ad libitum to 4 rumen fistulated Holstein-Friesian steers, weighing approximately
350 kg, for two consecutive weeks before a metabolism trial was imposed for 5 days to measure voluntary
intake, digestibility and pH, NH3-N and VFA in rumen fluid. In addition, various parts of the cassava hay:
leaf, branch, stem and whole crop were studied for rumen degradation at 0, 24, 48 and 72 hours post
feeding using the nylon-bag technique (Orskov and Shand 1997). Samples of feeds and faeces were
analysed for DM, N and NDF by conventional methods (AOAC 19).

Results and discussion
Yield of cassava hay:
The whole cassava crop can be harvested in the dry season, three months after planting for the first cut
and two times thereafter. The first cut at three months yielded 20,410 kg/ha (fresh) or 10,200 kg/ha
(dried). The combined second and third cuts were estimated to be equal to the first cut. Therefore
estimated total yield of cassava whole crop (fresh) and cassava hay were 40,820 kg/ha and 20,410 kg/ha,
respectively. The practical use of cassava hay for ruminant feeding could be planned and fed in the dry
season as shown in Figure 1. This feeding method would well follow recommendations previously given
by Preston and Leng (1987).
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Cassava hay: A new strategic feed for ruminants


Cassava hay preparation:
Cassava crop can be harvested about 6 inches above the ground and sun-dried for 3-5 days before being
collected in bundles or made into a square bale prior to feeding or storage for later dry season feeding. A
short drying period (2-3 days) is essential to secure leaf attachment and higher quality. However, a longer
period (4-6 days) is necessary for drying the stem and branches which contain higher content of moisture.
The drying process is not only to reduce moisture but also to decrease hydrocyanic acid to a safe level for
ruminants.
Nutritive value study:
The chemical composition of cassava hay is presented in Table l. All parts of the cassava foliage contain
high levels of crude protein; 32.3, 14.6, 8.9 and 24.9 % for leaf, stem, branch and whole crop hay,
respectively. Moreover, NDF, ADF and ADL contents were relatively low. A comparison between
cassava hay (CH) and alfalfa hay (AH) is presented in Table 2. CH has a higher level of CP and lower
levels of NDF, ADF and ADL. These data are in agreement with previous reports by Maaruf et al (1995).
With natural sun-drying, the hydro-cyanic acid was remarkably lowered to 0.38 mg% in CH which
suggested a safe level for ruminants.

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Cassava hay: A new strategic feed for ruminants

Table 3 presents data on intake and digestibility. Cassava hay was fed to steers as a sole source of feed
and it was well consumed at 11.2 kg/hd/d or 3.20 % of live weight.This intake was relatively higher than
other sources of roughage as a sole feed. Ruminal pH measured before and post-feeding was relatively
high (pH 6.95-7.11) which could possibly be due to high level of NH3-N. DM digestibility by the total
collection method measured on four steers was 71.0 1.23 %.

Table 4 and 5 present data on rumen degradation rates using the nylon-bag technique at 0, 24, 48, and 72
hr post feeding. Ruminal DM degradability of all parts showed linear increases as time progressed to 72
hr. Highest degradabilities were shown for leaf, whole crop and stem, while the branches resulted in the
lowest value. These high ruminal degradabilites supported high intakes as shown in Table 3.
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Cassava hay: A new strategic feed for ruminants
Rates of protein degradation of all parts were studied to relate to their by-pass protein characteristics since
tannin was reported to be high especially in the leaf portion. As clearly shown, leaf protein exhibited
highest "b" and "c" values, followed by whole crop hay.

Conclusions and recommendations
Based on this study, it can be concluded that cassava is highly recommended to be grown as foliage for
dry season feeding since it can easily grow in low-organic matter soil, at high ambient temperature and
with minimal management. Biomass production for first and subsequent harvests proved the potential of
this crop since this timing coincides well with the harsh dry season period when natural feeds are limited.
The high quality in terms of protein and content of digestible nutrients, together with high consumption
rate, prove that it is an excellent feed either for full feeding as cassava hay or as a supplement in crop-
residue based diets (eg: urea-treated straw, or sugar-cane tops). This new approach of using whole crop
cassava as hay needs to be implemented as a strategic feeding system during the dry season in a
sustainable livestock production system particularly in small-holder dairy farming.

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Cassava hay: A new strategic feed for ruminants
Acknowlegements
The authors wish to acknowledge support from the FAO/TCP project and Khon Kaen University and
express sincere thanks to all personnel engaged in this work, MS degree students and technicians.

References
AOAC 1990 Official Methods of Chemical Analysis. Association of Official Agricultural Chemists (15th ed)
Washington DC
Gohl B 1981 Tropical Feeds. FAO animal Production and Health Series No.12, FAO Rome.
Maaruf K D A, Christensen G L and Campbell 1995 Comparison of protein and cell wall degradation of
selected tropical and temperate roughages. Proceedings of The Second International Conference on Increasing
Animal Production with Local Resources (Editor: Guo Tingshuang). China Forestry Publishing House, Ministry of
Agriculture, China.
Orskov E R and Shand W J 1997 Use of the nylon bag technique for protein and energy evaluation and for
rumen environment studies in ruminants; Livestock Research for Rural Development. Volume 9, Number 1: 8-12
Preston T R and Leng R A 1987 Matching Ruminant Production Systems with Available Resources in the
Tropics and Subtropics. Penambul Books, Armidale, NSW, Australia.
Wanapat M 1995 The use of local feed resources for livestock production in Thailand. Proceedings of the
International Conference on Increasing Animal Production with Local Resources (Editor: Guo Tingshuang). China
Forestry Publishing House, Ministry of Agriculture, China.
Received 1 February 1997
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