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TITLE PAGE
EFFECT OF FEEDING UREA TREATED MAIZE
STOVER AND CENTROSEMA PUBESCENS ON
GRAZING N’DAMA CALVES
BY
EGBU, CHIDOZIE FREEDOM
REG NO: PG/M.Sc/11/58363
DEPARTMENT OF ANIMAL SCIENCE
FACULTY OF AGRICULTURE
UNIVERSITY OF NIGERIA, NSUKKA
FEBRUARY, 2014
ii
CERTIFICATION
EFFECT OF FEEDING UREA TREATED MAIZE
STOVER AND CENTROSEMA PUBESCENS ON
GRAZING N’DAMA CALVES
BY
EGBU, CHIDOZIE FREEDOM
REG. NO: PG/M.Sc/11/58363
A PROJECT SUBMITTED TO THE DEPARTMENT OF ANIMAL SCIENCE,
FACULTY OF AGRICULTURE, UNIVERSITY OF NIGERIA, NSUKKA IN
PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE
MASTER OF SCIENCE DEGREE IN ANIMAL NUTRITION AND BIOCHEMISTRY
(M.Sc) IN ANIMAL SCIENCE.
------------------------------------ --------------------------------
DR. A. E ONYIMONYI ESQ (JP) DR.A.E ONYIMONYI ESQ (JP)
PROJECT SUPERVISOR HEAD OF DEPARTMENT
-------------------------------------
EXTERNAL EXAMINER
iii
DECLARATION
The experimental work was carried out in the Department of Animal Science, Faculty of
Agriculture, University of Nigeria, Nsukka, under the supervision of Dr. A. E. Onyimonyi
Esq (JP).
These studies represent original work by the author and have not otherwise been submitted in
any form for any degree or diploma to any other University. Where use has been made of the
work of others, it has been duly acknowledged in the text and listed in reference and all help
by others have been duly acknowledged.
Egbu, Chidozie Freedom
iv
DEDICATION
I dedicate this research work to my loving parents Mr Egbu, Sunday and Mrs Egbu, Ijeoma
for their unwavering support for my education.
v
ACKNOWLEDGMENT
I wish to express my sincere and profound gratitude to my supervisor, Dr. Anselm Egoyibo
Onyimonyi Esq (JP) for his useful guidance, discussions, constructive comments, help in
getting the experimental animals and valuable sources of information he provided for me
throughout this study. His devoted interest is one of the qualities I most admire.
I sincerely appreciate the help received from the staff at the Cattle Unit of the Department of
Animal Science Research and Teaching Farm, University of Nigeria, Nsukka where most of
the practical work was conducted, the laboratory staff of the Department of Animal Science,
University of Nigeria, Nsukka for the analysis of feed samples, and the 2012/2013 fourth year
students of the Faculty of Agriculture for helping in harvesting, gathering and chopping of
the Centrosema pubescen.
Finally, I appreciate my friends and all postgraduate students from Department of Animal
Science, University of Nigeria, Nsukka for their support and encouragement throughout my
thesis.
I owe profound gratitude to my parents, Mr. and Mrs. Sunday Egbu, my uncle and his wife
Mr and Mrs Okolichukwu, my aunty Mrs Ezenwa, I. and to my sister and brothers, my
cousins for their diverse and invaluable assistance accorded to me during my period of study.
vi
TABLE OF CONTENTS
Title page - - - - - - - - - i
Certification - - - - - - - - - ii
Declaration - - - - - - - - - iii
Dedication - - - - - - - - - iv
Acknowledgment - - - - - - - - v
Table of contents - - - - - - - - vi
List of tables - - - - - - - - vii
Abstract - - - - - - - - vii
CHAPTER ONE - - - - - - - - 1
1.0 Introduction - - - - - - - - 1
1.2 Justification - - - - - - - - 2
1.3 Objectives of the Study - - - - - - 4
CHAPTER TWO:
2.0 LITERATURE REVIEW - - - - - - 5
2.1 Rumen Ecosystem - - - - - - - 5
2.2 Utilization of Crop Residues - - - - - - 6
2.3 Management of crop residues - - - - - - 8
2.4 Chemical composition of crop residues - - - - 8
2.5 Limitations of crop residues - - - - - - 9
2.6 Improvement of crop residues - - - - - 11
2.7 Principles of urea treatment - - - - - - 13
2.8 Effects of urea treatment on chemical composition of crop residues - 15
2.9 Effect of urea on voluntary feed intake of crop residue - - 17
2.10 Performance of animals fed urea treated crop residues - - 18
2.11 Effect of supplementing crop residues with legumes - - - 21
2.12 Effect of legume supplementation on nutrient utilization - - 23
2.13 Anti nutritional factors found in tropical legumes - - - 25
2.14 Mineral content of tropical legumes - - - - - 26
CHAPTER THREE:
3.0 MATERIALS AND METHOD - - - - - - 29
3.1 Location of study - - - - - - - - 29
3.2 Experimental diet - - - - - - - - 29
3.3 Experimental animals and management - - - - - 29
vii
3.4 Experimental design and data collection - - - - - 30
3.5 Chemical and data analysis - - - - - - 31
CHAPTER FOUR
4.0 RESULTS AND DISCUSSION - - - - - - 32
4.1 Results - - - - - - - - - 32
4.2 Discussions - - - - - - - - 33
CHAPTER FIVE
5.0 SUMMARY AND CONCLUSION - - - - - 36
REFERENCES - - - - - - - - 37
APPENDICES - - - - - - - - 51
viii
LIST OF TABLES
Table 2.1: Mineral content of tropical legumes - - - - - 27
Table 3.1: Percentage composition of the dietary treatments - - - - 31
Table 4.1: Proximate analysis of the experimental diets - - - - 32
Table 4.2: Growth performance of N’dama calves fed urea treated maize stover
and Centrosema pubescens - - - - - -- 32
Table 4.3: Linear body measurements of N’dama calves fed urea treated maize
stover and Centrosema pubescens - - - - - 33
Table 4.4: Blood parameters of N’dama calves fed urea treated maize stover and
Centrosema pubescens - - - - - - - 33
ix
ABSTRACT
Effects of urea treatment on chemical composition, feed intake, linear body measurements,
feed cost/kg gain, blood urea and ammonia of maize stover and the growth performance of
calves were investigated using 8 N’dama calves of 5 to 8 months of age and an average initial
live weight of 92.5 kg. The animals were divided into two groups each of which were
individually fed experimental diets of either untreated maize stover and Centrosema
pubescens (Diet A) or 5 % urea treated maize stover and Centrosema pubescens (Diet B) for
90 days. The calves were allowed free access to mineral/vitamin blocks and drinking water
ad libitum. Urea treatment increased the CP content of maize stover in Diet B by 22.12%
over the untreated stover in Diet A. Compared with the untreated stover, urea treatment
brought an improvement of 28% in daily feed intake. These improvements in terms of
chemical composition, daily feed intake led to a highly significant (p<0.01) live weight gain
of animals fed urea treated stover diet compared with those fed untreated stover diet. There
was no significant (p>0.05) difference in blood urea levels, feed cost/kg gain and linear body
measurements between the animals fed Diet A and those fed Diet B.
Therefore, urea ammoniation of maize stovers significantly (p<0.01) improved the chemical
composition of Diet B, daily feed intake and live weight gain of N’dama calves fed Diet B.
x
CHAPTER ONE
1.0 INTRODUCTION
The problems of ruminant feeding have received considerable attention in the tropics and
sub-tropics (Tesfayohannes, 2003). Most of the research has focused on treating roughage in
the late dry season when the quality and quantity of food supply from natural pastures
become limiting. Moreover, ruminant animals have evolved the ability to utilize and digest
fibrous materials. In contrast to the situation in the tropics and sub-tropics, in many
developed countries, foods that are suitable for human consumption are very often used for
feeding both monogastrics and ruminant animals. It has been suggested that ruminants should
be fed, as much as possible, roughage based diets and other feeds that are not directly used by
humans (Orskov, 1998). Thus, maize stover is becoming an important and staple feed for
ruminants in most parts of the developing world. This is because of an increase in animal
population density and failure to modify traditional grazing practices, especially in the arid
tropics and subtropics, which have caused serious deterioration of natural vegetation cover. In
many parts of the world today crop residues makes up 60 to 90 per cent of the bovine diet
(Verma and Jackson, 1984).
Though maize stovers is the most abundant of all agricultural residues and has a great
potential as a feed-stuff for ruminants, it appears that 1ivestock production based on these
stovers are rather low (Tesfayohannes, 2003). Verma and Jackson (1984) reported that nearly
half of the world's bovine population is reared and maintained on diets composed of 50% or
more stovers. Thus, these animals are the worlds least productive in terms of annual output
per animal. The reasons for this low level of production are the low digestibility and intake of
the maize stover based diets. Coxworth et al. (1977) reported that the voluntary intake and
digestibility of maize stovers are limited by its high lignin content, the manner in which this
indigestible material is bound to the digestible cellulose and hemicelluloses and its low
nitrogen concentration. Kamstra et al. (1958) and Van Soest (1967) reported that poor
digestibility is related to the extent of lignifications of the cell wall components of the low
quality roughages. The degree of fill in the reticulo-rumen has also been suggested as the
dominant factor limiting voluntary intake of poor quality roughage diets because they have
relatively long rumen retention times (Grovum and Williams, 1979). However, decreasing the
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retention time by increasing the rate of passage tends to decrease the extent of fiber digestion
in the rumen (Van Soest, 1982).
Chemical up-grading of maize stovers by means of ammoniation with gaseous or liquid
ammonia has received considerable attention in many countries (Sundstol and Coxworth,
1984). An alternative method of ammoniation, using urea as the source of ammonia has been
reported by several research workers (Saadullah et al., 1981; Hadjipanayiotou, 1982; Cloete
and Kritzinger, 1984; Dias-Da-Silva and Sandstol, 1986). According to Davis et al. (1983), of
all the alkalis tested, ammonia is the most preferred because it provides both the alkaline
effect and a source of nitrogen. However, alkali treatments are generally expensive and the
chemicals are not readily available in many parts of developing countries (Tesfayohannes,
2003). Consequently, urea has been studied as a source of ammonia for treating roughages
(Hadjipanayiotou, 1982; Cloete et al., 1983; Khanal et al., 1999). Many of the factors
influencing the effectiveness of crop residue treatment with urea (Cloete and Kritzinger,
1984, 1985), like type and level of chemical reaction, period, ambient temperature and
amount of water (moisture level), are closely related to the economics of maize stover
treatment (Hadjipanayiotou, 1989). With the increase in human and animal populations, and a
consequent reduction in the cropping and grazing land, it is possible that this strategy will be
attractive to many farmers in the future. However, unless adequate feed resources are made
available, grazing animals will continue to be undernourished with consequent low
productivity (Tesfayohannes, 2003).
Urea-ammoniation of maize strovers generally results in increased digestibility and intake
(Cloete and Kritzinger, 1984; Djajanegara and Doyle, 1989; Flachowsky, et al., 1996). There
is a view that urea-ammoniated diets such as barley, maize stovers, oat, wheat straw and oat
hay may not be adequate for production functions like growth, pregnancy and lactation
(Brand et al., 1991). Therefore, addition of legumes to urea-ammoniated diets could give
better results in the production function of animals. This is due to the fact that legumes based
diets are more digestible (Orskov and Ryle, 1990) and therefore more volatile fatty acid,
(VFA) are produced per unit weight than from forage. Evidence from the literature suggests
that the inclusion of protein at low levels may improve fiber digestibility (Williams, 1984).
For instance, it has been shown that tropical legumes are higher in protein and lower in fibre
than their grass counterparts, and thus could serve as valuable supplements to straw or stover-
based rations (Van Soest, 1994).
xii
1.2 JUSTIFICATION
Among the breeds of cattle domesticated in the tropics, the N’dama is the most common in
the South Eastern part of Nigeria. N’dama is hardy, trypano-tolerant and is best suitable for
the environmental condition of the South Eastern part of Nigeria. The N’dama is gradually
going into extinction and to preserve its genetic stock, one factor critical to its survival is
nutrition. During rainy season there is abundant pasture for them to feed on but as dry season
sets in feeding N’dama becomes problematic.
The problem of dry season livestock feeding, has directed research efforts towards harnessing
and enhancing the utilization of abundant arable by-products and crop residues. Maize is the
most common grain cultivated in the South Eastern part of Nigeria. During harvest, farmers
are only interested in the maize cob and large quantities of maize stovers produced on private
and government farms in Nigeria are wasted year after year. Some are left to rot in the field,
which may improve soil fertility anyway, but most are burned (Onyeonagu and Njoku, 2010).
Since, N’dama cattle are ruminants, they can feed on these maize stovers converting it to
meat for the teeming population of the South Eastern Nigeria.
Maize stovers are generally low in nutrients (Owen, 1994). In other to make maize stovers
useful to N’dama cattle, they need to be processed. Cereal crop residues are low in nutritive
value because of their relatively low digestibility, low crude protein content and low content
of available minerals and vitamins (Owen, 1994). Ani (2012) cited various strategies that
have been adopted in improving crop residue nutrients and utilisation and they include;
physical method (brisquetting, pelleting, extrusion, chopping, grinding), chemical method
(treating with Sodium hydroxide, wood ash, ammonia) and biological method (using fungi to
degrade lignin in crop residue and using solid state fermentation system). Efforts to improve
the nutritive value of the cereals residues through treatment with urea and other chemicals
have not been very popular because technologies are often at the ‘high tech’, for application
by small holder subsistence farmers (Owen and Jayasuriya, 1989).
The abundant supply of crop residues and agro-industrial by-products at reasonable prices
could enhance production and reduce cost of compounded feeds while not adversely affecting
the performance of the animals. Because of increases in human population and consequent
high cost and demand for conventional feedstuffs such as groundnut cake and soya bean
meal, it has become increasingly necessary that alternative feed ingredients be found to
reduce the competition between man and livestock (Iyeghe-Erakpotobor et al., 2002).There is
xiii
evidence that livestock fed with crop residues and agro-industrial by-products could achieve
substantial weight gains (O’Donovah, 1979).
The trend has changed from the situation in which maize stovers were considered as waste
and are now being converted to animal protein for human consumption (Singh et al., 2004
and Singh et al., 2011). There has been growing policy recognition of the role of non-
conventional feed resources in livestock production (FAO, 1999). Ruminants depend on two
major feed resources: these are crop residues and agro-industrial by-products and they play a
significant role in the nutrition of ruminant animals (Agarwal and Verma, 1983).
There is very little information on the actual availability and usage of crop residues and agro-
industrial by-products in the South Eastern Nigeria compared to the northern part
(Onyeonagu and Njoku, 2010). Inspite of the increasing importance of crop residues, there is
paucity of information available on crop residue in the South Eastern Nigeria.
1.3 OBJECTIVES OF THE STUDY
The objectives of this study were as follows:
1. To determine the improvement in chemical composition due to urea treatment of
maize stover as compared with the untreated stover and Centrosema pubescens.
2. To determine the potential of urea treated maize stover for growth and fattening
performances of N’dama calves during dry season in humid tropics.
3. To evaluate the economics of feeding urea treated maize stover as compared with
feeding untreated maize stover and Centrosema pubescens to N’dama calves.
4. To determine blood urea and ammonia levels of N’dama calves fed urea treated maize
stover as compared with feeding untreated maize stover and Centrosema pubescens.
xiv
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 RUMEN ECOSYSTEM
Ruminants offer an advantage over monogastric animals in that the rumen is well equipped
with a wide range of symbiotic organisms which, under favourable conditions, break down
otherwise indigestible roughage (Konimba, 1996). The microbes require a receptive
environment for desirable fermentation patterns. Rumen microbial populations consist of
three main groups- bacteria, protozoa and fungi. Although the type of substrate entering the
ecosystem will mainly determine the population (Orpin, 1983), several of the bacteria,
protozoa, and fungi species have been described in detail (Hungate, 1966). Microbial
population and fermentation patterns vary with changing rumen environment. A continual
supply of substrate, and salivary buffering salts and the removal of end products and residues
will result in a relatively stable rumen environment, thus promoting high microbial
populations and increased biomass (Konimba, 1996).
Rumen Bacteria
Several hundred species of bacteria have been found in the rumen and about 109-10
10 bacteria
per ml of rumen fluid have been estimated (Hungate, 1966). Among the different functional
groups - cellulolytic, amylolytic, and proteolytic bacteria, those which ferment cellulose are
the most important. Cellulolytic and amylolytic bacteria both require ammonia (NH3) and
branched chain fatty acids as growth factors. Dietary urea can provide NH3 and so promote
efficient utilization of fibrous roughage, if the rumen pH does not fall below about 6.0
(Orskov and Ryle, 1990). Microbial efficiency is also associated with the availability of
carbohydrates contained in the fibre (Konimba, 1996). For instance, it has been shown that
tropical legumes are higher in protein and lower in fibre than their grass counterparts, and
thus can serve as valuable supplements to straw or stover-based rations (Van Soest, 1994).
Rumen Protozoa
Rumen fluid contains up to 106/ml protozoa (Konimba, 1996). The cilia of these organisms
are restricted to tufts located mainly near the oesophagus; their function is the propulsion of
xv
food particles into the oesophagus. Two major groups of ciliate protozoa have been isolated,
Holotrichs and Entidiniomorphs (Hungate, 1966). The main substrates for the Holotrichs are
sugars and other soluble components, while the Entidiniomorphs survive on fibrous food
particles or bacteria (Konimba, 1996). The positive effect of rumen defaunation on the
digestibility of fibrous feeds and the live weight gain in sheep offered straw diets has been
reported (Soetanto, 1986; Bird and Leng, 1989).
Rumen Fungi
It was only when Orpin (1983) discovered rumen fungi that they were considered as a
functional group of microorganisms. Most of the fungal biomass is present as rhizoids
infiltrating fibrous plant tissue. Orskov and Ryle (1990) reported that this group of
microorganisms may be particularly important for the degradation of the plant structural
materials which predominate in coarse roughage, although lignin does not appear to be
susceptible to attack by rumen fungi.
2.2 UTILIZATION OF CROP RESIDUES
Large quantities of crop residues are used as animal feed in many countries, but much is still
wasted for various reasons or used for other purposes (Tesfaye, 2006). According to Timothy
et al. (1997), in south Asia, crop residues are used as compost and mulch for crop production,
bedding for livestock, as substrate for growing mushrooms, fiber for paper manufacture and
as fuel. In semiarid sub-Saharan Africa, they are used to control wind erosion and in the
construction of roofs, fences, granaries, beds and doormats.
With regard to the use of crop residues for animal feeding, Kossila (1985) reported that in
both developed and developing countries, crop residues account for about 24% of the total
feed energy suitable for ruminant livestock. The author further stated that if all crop residues
were considered, the total production would on average give 3.4 tons and 6166 Mcal
metabolizable energy (ME) per year in the whole world. Sandford (1989) reported that in
various parts of semiarid sub-Saharan Africa, cattle derive up to 45% of their total annual
feed intake from crop residues, and up to 80% during critical period. In a village survey
carried out in western Maharashtra, India, Thole et al. (1988) found that sorghum stover
contributed between 20 and 45% of the total dry matter feed provided to dairy animals by
small scale farmers.
xvi
Although crop residues are known to have such a significant contribution to the livestock
feed requirements, there are varying opportunities for their use as animal feeds (Thole et al.,
1988). The greatest potential for the use of crop residues as animal feeds exists in the mixed
crop/livestock systems (Kossila, 1985). Where crop and livestock production are segregated,
most crop residues are wasted or they are used for non-feed purposes (Kossila, 1985).
Generally, as production systems become more specialized, crop residues are likely to be
included in ruminant diets in lower proportions or only at phases of production with lower
nutritional requirements (Sandford, 1989). This is because, the specialized systems require
animals of highest genetic potential and feeds of better quality to achieve higher milk yields
or animal growth rates (Klopenstein and Owen, 1981). On the other hand, it was found that
crop residues can be a suitable feed in specialized beef (Klopenstein et al., 1987) and dairy
(Klopenstein and Owen, 1981) enterprises, particularly during phases when animal nutritional
demands are lowest.
Timothy et al. (1997) stated that the pattern of crop residue use is often dictated by
population density, herd management practices and level of transport and marketing
infrastructure. In areas with low population densities and where animals are herded
communally, they observed open access to residues to occur as opposed to densely populated
and heavily stocked areas in which restricted access to residues is practiced. Anderson (1978)
reported that the extent to which crop residues are utilized also varies with geographic
locations. In drier climates, the small amount of residues available makes it uneconomical to
gather and remove it, whereas in areas where the topography is steep it is essential to leave
residues on the soil to prevent water erosion and to allow adequate moisture penetration.
Moreover, as residues must be collected and transported for efficient utilization, the financial
capacity of the farmers to undertake such activities also becomes a major factor regulating
their extent of utilization.
The reliance on crop residues for livestock feeding increases as farm sizes decreases. In the
case of Eastern Kenya, Fernandez-Rivera et al. (1995) reported that farmers with only two ha
of land barely covered two-thirds of the feed needs of their livestock and are forced to exploit
their crop residues to the full, to herd their cattle along road side and on waste lands, to rent
grazing lands from other farmers or as a last resort, to purchase feed. Kayouli (1996) also
stated that as pasture production declined, ruminant animals in the Sahel have become more
dependent on crop residues which assumed progressively greater proportion of the total diet
being mainly used during the dry season.
xvii
In summary, the use of crop residues for animal feeding not only improves animal production
but it also increases the overall utilization efficiency of crops such as maize whose utilization
efficiency is low (Tesfaye, 2006). In this regard, Alemu et al. (1991) stated that when only
the grain is used for human consumption or for livestock feed, only about 39% of the energy
and 20% of the protein are utilized.
2.3 MANAGEMENT OF CROP RESIDUES
The practices used in crop residue management (harvesting, handling, collection and storage)
have effects on both the quantity and quality of the residues (Tesfaye, 2006). Owen and
Aboud (1988) stated that as straws and stovers comprise leaf and leaf sheath (the more
nutritious parts), the harvesting, handling and storing systems should minimize the loss of
these parts. They further warned that delayed harvesting or relay harvesting in an
intercropped field would be expected to cause greater loss of leaf and leaf sheath, with a
consequent reduction in nutritive value. Emphasizing the importance of crop residue
collection, Dyer et al. (1975) stated that the energy required to produce the world’s protein
needs through ruminant animals could be provided if only 5% of the waste cellulosic
materials could be economically collected and processed. According to Hilmerson et al.
(1984) and Owen and Aboud (1988) and, even if the effects of residue management are
acknowledged, the difficulty of handling and storing of crop residues have not been given
adequate attention by researchers.
The farmers’ decision as to whether or not to collect and store crop residues depends on many
factors which include the farmers’ capacity in terms of having means of transportation
(labour, capital, draught animal, etc.), availability of other feed resources, livestock
population and market availability (Tesfaye, 2006). The availability of labour, large livestock
population and easy access to markets encourage farmers to collect their residues from fields.
Once collected and stored, due attention must be given also as storage problems such as pest
infestation, moulding and fire may result in losses of the residues. Timothy et al. (1997)
stated that combined with seasonal nature of their production, storage problems can create an
annual cycle of brief peaks in crop residues availability followed by long periods of scarcity.
2.4 CHEMICAL COMPOSITION OF CROP RESIDUES
The chemical composition of roughages (DM basis) is variable. For instance, the crude
protein content may range from as little as 30 g kg-1
in mature herbage plants to over 300 g
xviii
kg-1
in young heavily fertilized grasses (McDonald et al., 1995). Fiber forms the bulk of most
tropical roughages and is considered as the sum of cellulose, hemicelluloses (xylans,
mannans, glucomannans, arabino-galactans) and pectin and all are inversely related to the
crude protein content. Crude fiber may vary from 200 to as much as 450 g kg-1
in mature
plant materials. In straws, the digestible cell contents constitute usually less than 250 g kg-1
of
the total dry matter (FAO, 1982) and therefore, it makes a minor contribution to the
evaluation of feeds depending on their nutritive value and nutritional importance. Generally,
cellulose content falls within the ranges 200 - 300 g kg-1
DM and hemicelluloses within the
range of 100 - 300 g kg-1
DM (McDonald et al., 1995). These polysaccharide components
increase with the maturity of the plant. The lignin concentration increases in the same manner
and adversely affects the digestibility of nutrients, except soluble carbohydrates (Akin and
Benner, 1988).
In a review by Butterworth and Mosi (1985) the mean crude protein percentage for good
quality hay was 7.7% (N content 12.3 g kg-1
). Low protein in roughages is generally
considered as one of the major constraints to optimum digestion. The range of neutral
detergent fiber (NDF) content of 70-81% is reduced, compared to 73-83% for the untreated
roughages. The high variability in chemical constituents could be attributed to the stage of
maturity of the plant, plant part, harvesting regime, season, location and type of the roughage
plant (McDonald et al., 1995).
The beneficial effects of feeding urea treated roughages to ruminants include increased
metabolizable energy intake, increased animal performance and feed efficiency, increased
availability of nutrients and improved rumen function (Pirie and Greenhalgh, 1978; Mgheni
et al., 1993). Habib et al. (1998) improved the nitrogen content of wheat straw from 4.12 to
9.83% through ammoniation and reported that this improvement in nitrogen content (9.83%)
is close to that found normally in the non-legume green fodders. The authors then concluded
that the added nitrogen in straw is one of the main advantages of ammonia treatment, which
could increase digestibility.
2.5 LIMITATIONS OF CROP RESIDUES
The most important factor influencing the production response of an animal is the total
quantity of nutrients absorbed (Poppi et al., 2000). Thus, intake and digestibility are key
parameters in any feed evaluation system, and of this, intake is the most important as it
accounts for most differences between feed types. The prime physical factor in a plant which
xix
influences voluntary intake is the rate at which it is broken down to particles small enough to
leave the rumen (Minson, 1982a). Becker and Lohrmann (1992) suggested that the most
significant effect of lignifications is on the rate of forage digestion rather than its possible
relation to the proportion of dry matter ultimately digested. Plant maturation is accompanied
by an increase in the proportion of fiber and a reduction in the protein and non-structural
carbohydrates of the cell content (Egan, 1986).
In most tropical roughages, the quality of feed at the beginning of the rainy season is high but
because of high temperatures, rapid physiological maturation takes place leading to early
lignifications with the protein and phosphorus contents falling to very low levels while the
fiber content increases (Becker and Lohrmann, 1992; McDonald et al., 1995; Nyamangara
and Ndlovu, 1995). Lignifications confer resistance to roughage fiber, thus decreasing
mechanical and microbial degradation in the rumen, which could explain the long retention
time of tropical roughages in the rumen. Long retention time facilitates rumen fill and
consequently decreases feed intake (Thorton and Minson, 1973; Aitchison et al., 1986).
Most tropical grass species belong to the C4 category of plants in which carbon dioxide is
first fixed in a reaction involving a 4-carbon compound, oxalate (Egan, 1986), while
temperate species belong to the C3 category of plants in which a 3-carbon compound,
phosphoglycerate acts as an important intermediate in the photosynthetic fixation of carbon
dioxide (Wilson, 1993). The low protein and sulphur contents usually found in tropical
grasses are inherent characteristics of C4 plant metabolism (Egan, 1986) that is associated
with survival under conditions of low soil fertility. In tropical grasses, starches are the main
storage carbohydrates, but these are replaced by fructans in temperate ones.
The plant cell wall has been shown to be the primary restrictive determinant of forage intake
(Van Soest, 1994). Tropical and subtropical forages are stemmier and have more cell wall
than the temperate forage species (Meissner, 1997). These results in low digestibility, slow
rate of fermentation and particle size reduction, which slow down the passage rate of residue
from the rumen, increase rumen fill and thereby reduce intake (Minson, 1982a). In South
Africa, cell wall constituents that have been shown to be correlated with intake include NDF
(Meissner et al., 1991), ADF (Cloete and Kritzinger, 1985) and acid detergent lignin (ADL)
(Pietersen et al., 1993). Van Soest (1965) reported that the intake was limited above NDF
concentrations of 550-600 g kg-1
DM but not below. Similar evidence was presented by
Meissner et al. (1991). Non-cell wall constituents that limit the intake and digestibility of
xx
tropical and subtropical forages include phenolic compounds (ferulic, deferulic, P-coumaric
acids and vanillin).
This limitation could be overcome by physical or alkali treatment or by improving the
activity of the rumen microbiota. Treatment with alkali (e.g. ammonia and/or urea)
hydrolyses lignin-hemicelluloses linkages, thus opening up the structure for bacterial
attachment (Sundstol and Owen, 1984), and hence increasing the availability of roughage
energy.
Kossila (1985) indicated that if all the potentially available crop residues could be utilized for
feeding, each herbivore would receive over 9 kg DM and about 17 Mcal ME/day, thus largely
covering requirements. Unfortunately, a much lower level of utilization is possible because of
problems of collection, transportation, storage and processing, alternative uses, seasonal
availability, and more importantly, their poor feeding value. Smith (1993) stated that most
crop residues are deficient in protein, essential minerals like sodium, phosphorous and
calcium, and are rather fibrous (40 to 45% crude fiber). The consequences of such a profile
for ruminants are a low intake (1.0 to 1.25 kg DM/100 kg live weight), poor digestibility of
the order of 30 to 45%, and a low level of performance. Low intakes and poor digestibility
result specifically from high cell wall lignin content and the chemical bonding between this
fraction and the potentially nutritious cell wall constituents such as cellulose and
hemicelluloses. Preston and Leng (1986) also reported that when straws are fed to ruminants
the primary limitations to production are: the slow rate of and low total digestibility, the rate
at which straw particles break down to a size that can leave the rumen, the low propionate
fermentation pattern in the rumen, and the negligible content of both fermentable nitrogen
and by-pass protein. The mineral content of straws is generally low and imbalanced but
deficiencies are unlikely to be manifested in animals at maintenance. For production of meat
and milk, requirements for minerals are increased many folds and supplements should be
supplied. Because of limited nutrients in fibrous feeds such as crop residues, Preston and
Leng (1984) and Leng (1990) suggested several methods which improve the usefulness of
these feed resources by establishing optimal rumen ecology with optimal ammonia (NH3)
nitrogen, increasing the ratio between energy and protein, and providing supplemental by-
pass or protected protein and fat.
2.6 IMPROVENT OF CROP RESIDUES
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Studies on factors influencing the quality of feeds have indicated that various factors
substantially change nutrient concentration and availability to the animal. Among the major
factors identified, genetic makeup of the plant, its environment and management practices are
the major ones (Norton, 1982; Wilson, 1982). Thus, no absolute figures of nutritional
characteristics of a feed could be established across regions and genotypes. Many techniques
are available for improving the nutritive value of roughages. Methods currently employed to
enhance digestibility and intake of the basal roughage diet range from physical through
chemical treatment to supplementation.
Physical or Mechanical Treatment
Physical or mechanical treatments, such as chopping, grinding, pelleting and steaming have
long been used to improve the nutritive value of low quality roughages, including maize
stovers (Minson, 1963; Walker, 1984). All the above treatments cause physical disruption of
cells and have limited effect on digestibility, but often improve roughage intake. Improved
digestibility is partly a result of enlarged surface area caused by grinding and thus improving
the possibility for the attachment of rumen microbes. Improved intake is achieved through a
faster rate of passage through the rumen, which in turn might cause a decrease in
digestibility. Besides, it is probable that species, age of the animal, origin of the plant
material, and the conditions under which the material is fed also affect utilization of the feed
irrespective of the particle size (Walker, 1984). This method facilitates maximal use of
roughage by creating more favourable condition for the host animal to eat more feed.
Chemical Treatment
Several alkali compounds (NaOH, Ca(OH)z, KOH) have been tested , but sodium hydroxide
has been the most successful in improving nutritive value of roughages (Church, 1984). The
use of sodium hydroxide (NaOH) treatment to increase digestibility of straws has been
known for more than a century. Homb 1984 involved the pressure cooking of straws in dilute
solutions of sodium hydroxide, followed by washing with clean water to remove the alkali.
Clearly this was an expensive method because of the severe processing and problems of
environmental pollution. This method was later modified by Beckman (1921), who replaced
pressure-cooking with simple soaking. In the Beckman method, rye straw is treated in 1.5%
NaOH solution for three days and thereafter rinsed with water. This method of treatment
increased the organic matter digestibility (OMD) of rye straw from 46 to 71%, which was
xxii
lower than the 88% achieved by (Wilson and Pigden, 1964). Straw treated by the Beckman
method turned out to be more expensive than other feeds (Jackson, 1978).
Although NaOH is effective in improving the digestibility of low quality roughage it has
some drawbacks. The alkali solution is dangerous to handle. Besides being a potential
pollutant in case of storage leakage, the large quantities of sodium (Na) being imported to the
farm and excreted in urine and faeces are far above what is required for plant growth. In most
countries NaOH is expensive and not available. Due to this concern it was necessary to look
for alternatives that were cheap and effective improving the nutritive value of straw and safe
for the environment.
Treatment with ammonia (Sundstol and Coxworth, 1984) and urea (Jewell and Campling,
1986; Flachowsky et al., 1996) has resulted in increased forage digestibility, voluntary intake
and animal performance. Accordingly, Djibrillou et al. (1998) reported that urea and/or
ammonia is preferred over other treatments as it has an added advantage of increasing the N
content of the straw. As a result of several advantages over sodium hydroxide treatment, like
ease of application, nitrogen addition and absence of undesirable residues, ammoniation is
also a popular chemical method of upgrading crop residues (Sundstol, 1984). However,
limited availability and increased regulation on transportation may limit the use of anhydrous
ammonia in certain regions of the tropics.
Urea is widely available and has been used as a source of ammoniation to improve the
feeding value of various grasses and crop residues (Sundstol and Coxworth, 1984). Urea
treatment is relatively easy to apply and its ability to swell cellulosic fibers is as effective as
that of NaOH (Khanal et al., 1999). In addition to the upgrading effect of urea treatment the
added nitrogen from ammonia also enhances microbial activity in the rumen, resulting to
increased synthesis of microbial protein.
2.7 PRINCIPLES OF UREA TREATMENT
Chenost and Kayouli (1997) described the process of urea treatment as a simple technique
consisting of spraying a solution of urea onto the dry mass of forage and covering with
materials locally available so as to form a hermetic seal. The process involves the hydrolysis
of urea into gaseous ammonia and carbonic gas through reaction with an enzyme called
urease which is produced by ureolytic bacteria within the forage being treated. The ammonia
xxiii
thus generated provokes the alkaline reaction which gradually spreads and treats the forage
mass. The hydrolysis reaction in the presence of urease and heat is as follows:
CO (NH2)2 + H2O 2NH3 + CO2
According to a report by Kayouli (1996), urea treatment developed in Niger, was a simple
technique that made use of locally available materials. Stovers and straws were treated with
5% urea (5 kg urea dissolved in 50 litters of water to treat 100 kg dry residue) and made into
a stack using the traditional storage method and locally available air-tight system: silos made
from Andropogon gayanus or briquettes made from clay and straw. Air-tightness was
successfully ensured by tying with braids made from Andropogon gayanus and no plastic
sheets were required.
The principle underlying urea treatment is that the ammonia generated from urea by bacterial
and/or plant ureases in the ensiling process hydrolyses the chemical/physical bonds between
lignin and the cellulose and hemicelluloses in the plant cell wall. The hydrolysis of these
bonds makes the cellulose and hemicelluloses more accessible to microorganisms in the
rumen and increases total fermentation and usually the rate of fermentation. Some chemical
hydrolysis of hemicelluloses also takes place resulting in an increase in the portion of soluble
carbohydrates in the straw (FAO, 1986). Response to urea treatment is thus a combination of
the effect of the alkali on cell wall structure and the effect of added nitrogen on rumen
microbial activity (Preston and Leng, 1984).
Chenost and Kayouli (1997) stated that the success in urea treatment depends on
interdependent factors such as the presence of urease, the rate of urea applied, the moisture
content, the ambient temperature, length of the treatment period, the degree of the hermetic
sealing achieved during treatment and the quality of forage to be treated.
From the report of Chenost and Kayouli (1997) regarding urea application rate, it is now well
established that the optimum rates lie between 4 and 6 kg urea per 100 kg of straw matter
which corresponds to treating with ammonia in a range of 2.27 to 3.4 kg (one molecule of
urea, (60 g) generates two molecules of ammonia, that is 34 g). The level of 4 to 5 kg urea for
treatment of 100 kg dry straw has been widely used in many countries such as Thailand,
China and Sri Lanka (Chenost and Kayouli, 1997). In other countries, levels as high as 6 to 7
kg per 100 kg dry straws were used. Bui and Le (2001) on the other hand, stated that, though
xxiv
DM, crude fiber (CF) and organic matter (OM) degradability of rice straw treated with 4 or
5% urea were slightly higher than that of the straw treated with 2.25% urea plus 0.5% lime,
the latter treatment seemed to be the reasonable alternative for farmers to accept the
technique due to the fact that urea was rather expensive in Vietnam. In this case, the
treatment time was 7 days. Nguyen et al. (1998) also suggested that 3% urea plus 0.5%
calcium hydroxide may be more economical than 5% urea in treating rice straw provided that
it has good effects on digestibility and intake of the straw by ruminants. The premise of their
suggestion is that when urea level was from 3% to 5%, only 17.4 % of the additional urea
nitrogen was fixed indicating loss of nitrogen when the level of urea applied is high due to
the anaerobic activities of microorganisms. In addition, the authors remarked that the partial
replacement of urea with calcium hydroxide could be technically and economically justified.
Based on the available knowledge for urea treatment, Said and Wanyoike (1987)
recommended that smallholders in Kenya should treat their maize stover with 5% urea
(batches of 10 kg chopped stover sprinkled with urea solution made of 0.5 kg urea dissolved
in 10 liters of water) for two weeks.
Preston and Leng (1984) indicated that, as a rule of thumb, 30 g N per kg digestible organic
matter (DOM) is required to maximize the development of rumen microbes. According to
Durand (1989), the total level of nitrogen required to optimize the activity of rumen microbes
is 26 g N per kg DOM. In accordance with these recommendations, Nguyen (2000) stated
that straw treatment with 4 % urea is an expensive way of supplying nitrogen as the level is
required for effective treatment but is much greater than what is needed by the rumen
microbes.
2.8 EFFECTS OF UREA TREATMENT ON CHEMICAL COMPOSITION OF
CROP RESIDUES
According to the Chenost and Kayouli (1997), the effects of ammonia generated during urea
treatment are: dissolving the parietal carbohydrate mainly the hemicelluloses, swelling the
vegetal mater in an aqueous environment, so easing access by the rumen cellulolytic
microorganisms, easing mastication by the animals and digestion by the microorganisms by
reducing the physical strength of cells and enriching the forage in nitrogen content.
xxv
The net effect of the treatment process is increased nutritive value through increasing forage
digestibility by as much as 8 to 10 points, nitrogen content by more than double and intake by
as much as 25 to 50%.
The effect of urea treatment in improving the nutritive value of crop residues varies between
leguminous and none-leguminous residues. By using sheep to assess the nutritive value of
urea-treated straws and legume haulms, Butterworth and Mosi (1985) observed no response
to treatment when a mixture of haricot bean and horse bean haulms treated with 4% urea was
fed to sheep. They attributed this to the higher level of lignin in the forages. On the other
hand, the authors found that the digestibility of tef straw was significantly improved by the
4% urea treatment and that, was associated with a decrease in both ADF and NDF fractions
of the forage and a relatively low level of lignin. Wongsrikeao and Wanapat (1985)
investigated the effect of urea treatment of rice straw on feed intake and live weight gain of
buffaloes. They reported a 92.8% dry matter and 3.8% crude protein for untreated straw as
compared to 60.8% dry matter and 6.8% crude protein for a 6% urea-treated straw. Similarly,
the dry matter digestibility of the treated straw was higher (55.4%) than that of the untreated
straw (43.2%).
From their study on sorghum head residue, Chairatanayuth and Wannamolee (1987)
concluded that urea or urea in combination with water melon seeds (source of urease to
reduce the storage time during treatment) can successfully be used as a treatment to improve
nutritive value of the residue. They found a higher protein content for the urea treated residue
than the control and the sodium hydroxide (NaOH) treated residues. The values reported for
the control, the 5% urea treatment and the 5% NaOH treatment after a storage period of 21
days were 4.5, 10.4 and 4.6%, respectively. However, urea treatment in this case was found
to be slightly less efficient than NaOH in improving in vitro dry matter digestibility
(IVDMD) of the residue (65.4 vs. 69.6%).
A comparative study conducted to evaluate the effects of alkali treatment of barley straw on
digestibility and metabolizability (Wanapat et al., 1986) revealed an enhanced CP content (21
versus 139 g per kg DM) and reduced both NDF and ADF contents due to 5% urea treatment.
Moreover, digestibility of nutrients, especially of CP, ether extracts (EE) and crude fiber (CF)
as measured in sheep was enhanced after urea treatment. However, the increases in DM and
OM digestibility were only 4 and 7 percentage units, respectively. Tran and Nguyen (2000)
investigated the effects on chemical composition of four levels of urea (1.5, 2, 2.5 and 3%,
xxvi
w/w) used to treat maize stover for 4 different periods (1, 30, 60 and 90 days). From the
results, they concluded that the CP content of the treated maize stover increased and its CF
decreased with increasing levels of urea. Shen et al. (1998) conducted a study on untreated
and urea treated rice straw to estimate the differences in straw degradation among different
varieties. According to their finding, urea treatment significantly increased straw DM and
OM degradability. On average, the DM and OM degradability of the straw after 96 hour
incubation were improved by 18 and 24.5%, respectively. Brand et al. (1991) observed a
marked increase in nitrogen content of ammoniated (with 55 g urea/kg straw) wheat straw. It
could be observed, ammoniation generally causes a reduction in the NDF and hemicelluloses
contents of crop residues. However, they obtained no conclusive evidence of such reduction
in their investigation. Moreover, these authors reported improvements of 7.9, 18.9, 13.7 and
36.5%, respectively in apparent digestibility coefficients of OM, cell wall constituents, ADF
and hemicelluloses of urea-ammoniated wheat straw compared with the untreated straw diets.
According to Orskov et al. (1990) in many countries, particularly in Asian cropping areas,
where straw is the main feed for ruminants, a proportional increase of 0.1 in digestibility of
straw can have enormous implications for resource availability and thus animal production.
This enables straws to form a large proportion of the diet of the animals receiving mainly
straws to achieve a better performance.
The addition of urea to stover at feeding as a supplement only corrects the deficiency in
nitrogen without overcoming the limitations of cell wall lignifications on intake and
digestibility (Brand et al., 1991). On low quality roughage diets such as crop residues, the
utilization of urea for microbial protein synthesis is primarily limited by the low availability
of fermentable energy (Flachowsky et al., 1996). Thus, it would be expected that the
efficiency of utilization of the ammonia nitrogen would be greater with stover treated with
urea compared with stover supplemented with urea because of the higher DM degradability
and hence the more energy obtained from the urea treated stover diet. Flachowsky et al.
(1996) stated that the nitrogen incorporated during treatment is readily available for use by
rumen microbes as confirmed by the high rumen ammonia levels on urea treated stover.
Fermentable energy supplements such as molasses may further increase the efficiency of
incorporation of urea nitrogen to microbial protein in the rumen. Supplementation with
readily fermentable carbohydrates in the absence of rumen degradable nitrogen cannot be
expected to improve the utilization of poor quality roughages by ruminants (Castrillo et al.,
1995).
xxvii
2.9 EFFECT OF UREA ON VOLUNTARY FEED INTAKE OF CROP RESIDUE
The quality of any roughage depends on the voluntary intake of that roughage and on the
extent to which its dry matter (DM) can supply dietary energy, protein, minerals and vitamins
when eaten by the animal (Kossila, 1985). Many factors influence the intake of roughages
among which are feed characteristics, animal species, physiological state and management
practices (Khanal et al., 1999). Most straws contain about 70-80% cell wall constituents,
which represent an energy source for ruminants. Voluntary feed intake (VFI) is the amount of
food eaten by an animal during a given period of time when an excess of the food is available
(Sundstol and Coxworth, 1984). Food intake is important in defining food conversion
efficiency (FCE). Efficient food conversion, however, will be achieved only if an animal is
able to obtain from the food a substantial margin of nutrients above maintenance
requirements. In many animal production systems, maximum intake may not be sufficient to
ensure maximum production, or may be critical to the system (Jewell and Campling, 1986).
Treatment of roughages with either urea or ammonia is an effort to increase intake (Castrillo
et al., 1995; Flachowsky et al., 1996) through alkaline hydrolysis of lignocelluloses bonds
(Sundstol and Owen, 1984) and to increase nitrogen concentration in the roughage. This
would allow an even release of ammonia in the rumen, creating favourable conditions for
intense microbial fermentation. Voluntary feed intake has been found to increase when
treated roughage is made available to ruminants (Jewell and Campling, 1986; Silva et al.,
1989; Brand et al., 1991). Aitchison et al. (1988) offered urea treated and urea supplemented
straw (i.e. straw sprayed with urea before feeding) to mature sheep and found a 21% increase
in dry matter (DM) intake for animals fed urea treated straw. Increased roughage intake due
to urea treatment has been reported (Joy et al., 1992; Fahmy and Klopfenstein, 1994; Brown
and Adjei, 1995; Schiere and de Wit, 1995). Similarly, Fahmy and Orskov (1984) reported
that the OM intake of ammonia treated barley straw was 73% higher than for the untreated
straw and the intake of digestible organic matter was improved by 98%. A linear increase in
intake of cereal straws has also been observed with urea treatment up to 7% (Macdearmid et
al., 1988) and 8% (Jayasuriya and Perera, 1982) of the roughage OM. The digestible organic
matter intake of rice straw was also increased by 0.42 and 0.27 kg day-1
due to urea and
ammonia treatment, respectively compared with untreated straws.
In an experiment, Manyuchi et al. (1992) reported that treatment of straw with ammonia or
supplementing straw with 200 or 400g of ammonia treated straw resulted in an 80, 56 and
xxviii
59% increase in intake, respectively. The report by Silva et al. (1989) showed an increase of
OM intake from 414 to 729 g/day in sheep and from 4.75 to 6.09 kg day-1
in cattle due to
ammoniation. Mira et al. (1983) observed that steers offered urea treated straw consumed
1.36±0.236kg day-1
more than those offered untreated straw. Hadjipanayiotou et al. (1997)
reported higher values of voluntary intake of urea treated straw relative to untreated straw.
Superiority of urea treatment as opposed to urea supplementation has also been reported for
voluntary intake. Khanal et al. (1999) reported an increase of 17.4% in OM intake after
animals were fed urea treated wheat straw. Experimental evidence (Cloete and Kritzinger,
1984) indicates that the voluntary intake of ammoniated wheat straw by sheep was increased
by 8.1% and 46.7% over that of urea supplemented and non-supplemented straw,
respectively.
The beneficial effect of urea treatment in ruminant diets has been associated mainly with the
increase in N for better utilization of roughages. Significant improvement in rumen
environment (Silva and Orskov, 1988) and higher live weight gain (Castrillo et al., 1995;
Flachowsky et al., 1996) were found after urea-treated barley straw diets were fed to
ruminants. Hadjipanayiotou et al. (1997) identified a 12.4% improvement in weight gain of
crossbred heifers fed urea treated barley straw relative to urea-supplemented diet.
2.10 PERFORMANCE OF ANIMALS FED UREA TREATED CROP RESIDUES
In Niger, Kayouli (1996) observed that the consumption of urea-treated forages during dry
season is often accompanied by an improvement in body condition of the animals and
maintenance of live weight. The animals were also more resistant to diseases and their coat
was improved (brighter hair). Thin and weak animals recuperated rapidly and milk from dairy
cows increased significantly. Moreover, farmers have noted a positive effect on animal
fattening in such a way that the fattening period was reduced with a consequent saving in
concentrates. According to Preston and Leng (1986), the technique of using urea-treated
forages also enables the use of animals with higher genetic merits as these animals can
consume much of the digestible feeds to meet their requirements. Another positive effect of
urea treated forages, observed by Kayouli (1996), is that feeding of such forages to draught
oxen resulted in improved body condition with no loss of weight during ploughing period.
Moreover, animals worked harder and longer (often ploughed 1.5 to 2 hours more per day)
than those fed on untreated straws and stovers.
xxix
Urea treatment increases the acceptability and voluntary intake of the treated straw as
compared with the untreated straw when it is fed ad libitum. The increase in intake is very
important because what and how much animals eat (their feed intakes) are the most important
factors that determine the productivity of ruminants (Kayouli, 1996). In this regard,
Wongsrikeao and Wanapat (1985) found a significant difference in dry matter intake between
the urea treated and untreated rice straw with values of 5.87 and 7.32 kg per day for untreated
and treated straw, respectively. In terms of animal performance, those animals that fed the
urea treated straw gained 0.21 kg/day while those that fed the untreated straw lost 0.13 kg per
day.
From feeding of 2.5% urea treated maize stover as a sole source of roughage to growing
cattle, Tran and Nguyen (2000) found that the treated straw had positive effects upon intake,
digestibility and growth rates of the animals during a 60-days feeding trial. In a trial which
compared the relative effectiveness of ammoniation using urea and supplementing untreated
rice straw with a molasses-urea block (MUB), Bui and Le (2001) found consistently higher
growth rates for crossbred cattle on ammoniated straw compared with those on the MUB
supplemented untreated straw (449 vs. 363 g per head per day). The improvement in growth
rate due to urea treatment was 25% (p<0.001). The DM intake of the straw was also higher
(p<0.001) for the group fed ammoniated straw than those fed the straw supplemented with
MUB.
Although moderate rates of live weight gain can be obtained with ruminants on diets based
on treated crop residues, better animal performances require supplementation of such residues
with nutrients that have beneficial effects on rumen function. Research works done in
Thailand and Australia depicted that the critical supplementary nutrients on a straw based diet
are bypass protein, starch and long chain fatty acids. High rates of growth were obtained
when the ammoniated straw (urea ensiling in Thailand and ammonia gas in Australia) was
supplemented with starch, protein and oil in the by-product meals that are known to escape
rumen fermentation (Elliot et al., 1978a and 1978b). Live weight gain of young Brahman
bulls weighing 150 kg increased from 0.47 to 0.83 kg/day as the level of supplementation of
ammoniated rice straw with a mixture of fat, protein and rice starch increased from 1 to 3
kg/day (Wanapat et al., 1986). In another study on the effects of various levels of bypass
protein supplementation on the body weight change of cattle given diet of ammonia treated or
untreated rice straw, sole treated rice straw gave 52.1% more growth rate than the untreated
xxx
one. The live weight gain further increased to as high as 639 and 365 g/day due to protein
meal supplement on treated and untreated straw, respectively (Preston and Leng, 1986).
By feeding urea treated wheat straw with limited amount of concentrate composed of
cottonseed cake and wheat bran to Chinese cattle, Ma et al. (1990) found considerable
improvement in 48 hours degradability (69.4 and 47.3% for treated and untreated straw,
respectively). Moreover, the ammoniation resulted in faster and more efficient growth and
was also cost effective. The percentage improvement obtained in daily weight gain, DM
conversion and cost of feed per kg gain due to treatment were 341% (485 vs. 110g), 76.4%
(10.8 vs. 44.3) and 64% (1.82 vs. 5.0 Yuan), respectively. In another study by Gao (2000),
Chinese Yellow cattle (young bulls) of 160 to 210 kg live weight and 12 to 14 months of age
were fed wheat straw treated with anhydrous ammonia or urea plus 1.0, 1.5 and 2 kg/day of
cotton seed cake. Though the live weight gains of animals given the anhydrous ammonia
treated straw were significantly higher than that of the animals given urea treated straw, daily
weight gains of 602, 687 and 733 g were attained for urea treatment plus the 1.0, 1.5 and 2
kg/day of supplement, respectively.
From their study with yearling crossbred (Friesian x Malawi Zebu) cattle, Munthali et al.
(1992) reported the highest live weight gain for animals fed 4% urea treated maize stover
supplemented with 2 to 3 kg maize bran per day. The authors attributed the improvement in
live weight gain to the increased intake of energy and an accompanying improvement in the
utilization of non-protein nitrogen in the urea treated straw. Study at ILCA (1983) has also
indicated that mature non-working oxen fattened readily on straw-based diets when given
fermentable nitrogen such as urea and small amounts of oilseed cakes.
Promma et al. (1985) studied the effects of urea treated rice straw on growth and milk
production of crossbred Holstein Friesian dairy cattle. From the results they concluded that
urea treated rice straw with concentrates, minerals and vitamins can be used instead of other
preserved feeds such as grass hay, silage or fresh grass as no differences were found in live
weight gain of the heifers.
2.11 EFFECT OF SUPPLEMENTING CROP RESIDUES WITH LEGUMES
xxxi
For appreciable microbial digestion of plant materials to occur in the rumen, a close physical
association is essential between the plant tissue and the microbes responsible for the digestion
(Cheng et al., 1984; Orpin, 1983). It is known that enzymic activity is likely to be
proportional to the mass of cellulolytic microorganisms. Yates (1984) has shown for cotton
thread, that the rate of cellulose digestion is correlated with the mass of attached colonizing
microbes, supporting this theory. Leng (1990) pointed out that farmers in developing
countries have generally recognized the benefits to cattle of adding a small amount of fresh
green herbage to straw-based diets. These practices have a number of beneficial effects,
which include the supply of vitamin A and essential minerals and of ammonia and
peptides/amino acids.
The role of supplements on the digestibility of a poor-quality basal diet has been investigated
(Ndlovu and Buchanan-Smith, 1985; Silva and Orskov, 1988). These studies showed that
where the supplemental forage in a straw-based diet given to sheep was of high digestibility,
a boost to digestibility of the basal diet occurred even at relatively small levels of
supplementation. The rate of digestibility of straw depends on the rate and extent of
colonization of fibre and the biomass of adherent organisms (Cheng et al., 1990). It has
always been assumed that colonization of fibre entering the rumen is from the free-floating
pool of bacteria in the rumen. Krebs et al. (1989) suggested that colonization of bacteria
occurs from fibre to fibre without passing through the free-floating pool, however. An
explanation given by Leng (1990) to this suggestion was that the beneficial effects of the
incorporation of high digestible forage in an otherwise low-digestible forage diet could be
that this exerts a large effect on digestibility by providing a highly colonized fibre source to
‘seed’ bacteria onto the less-digestible fibre. Supplementation with legume crop residues
contributes fermentable energy to the rumen in the form of available cellulose and
hemicelluloses which stimulate fibre digestion (Silva and Orskov, 1985). According to
Bauchop (1981), it is possible that offering such material prior to the daily feeding of straw
may induce a greater degree of colonization of straw by rumen bacteria and by rumen fungi,
which have been implicated in the breakdown of fibre. Other factors may be involved. For
instance, Orskov and Dolberg (1984) stated that if animals fed untreated straws or poor
quality roughages are supplemented with substrates which increase the fermentation rate of
cellulose, the rumen environment becomes similar to that of animals receiving ammonia-
treated straws.
xxxii
Topps (1995) in his review stated that the positive effect of forage legume supplements on
the activity of the rumen microorganisms and a concomitant increase in degradation of fibre
has been recorded. However, such an effect was not seen with some poor quality roughages.
In a study by McMeniman et al. (1988), five legumes were used as supplements to rice straw.
The degradation of the straw was increased by each legume. Similarly, Ndlovu and
Buchanan-Smith, (1985) found that lucerne increased the rate of degradation of barley straw,
brome grass and maize cobs. In contrast, Manyuchi (1994) reported that groundnut hay did
not alter the in sacco degradation of poor quality grass hay. According to Akin (1989), it is
likely that any change in the degradation of the basal diet as a result of an increase in
microbial activity may depend on the number of available sites for microbial attachment.
With some roughage the cuticle layer and extent of lignifications are barriers to microbial
colonization so that an increase in rumen microbial population may not be reflected in an
increase in rate of degradation.
Few studies have been carried out in which changes in the rumen environment have been
measured when forage legumes are fed with poor quality basal diets (Topps, 1995). It is well
known that poor quality forages provide insufficient degradable nitrogen and fermentable
energy to sustain optimum digestion of fibre. Furthermore, rumen microbes require a source
of fermentable nitrogen, usually as ammonia although; some microbial species require
preformed amino acids and peptides (Russell and Baldwin, 1978). The ideal N concentration
in the rumen for efficient digestion has been variously estimated at 50-70 mg/litre (Satter and
Slyter, 1974) and at 150-200 mg/litre (Krebs and Leng, 1984). However, Ndlovu (1991)
reported that these levels are not easy to maintain install-fed animals over 24- hour,
particularly if the feed is mature grass and it is fed in insufficient quantities. Forage legumes
are relatively good sources of degradable nitrogen and fermentable energy so their inclusion
in the diet is likely to increase the rumen population of cellulolytic microbes (Topps, 1995).
Concentrations of rumen ammonia have been increased following supplementation with
forage legumes (Getachew et al., 1994; Manyuchi, 1994; Kimambo et al., 1991), the increase
being a function of the degradability of the nitrogen in the forage legume. In a study by Said
and Tolera (1993), the legume with the lower nitrogen content (Macrotyloma. axillare) gave
higher rumen ammonia levels than Desmodium intortum which had more crude protein but
with a lower degradability. For certain forage legumes, especially certain species of shrubs,
the availability of the nitrogen compounds would be limited by tannins (Manyuchi, 1994).
Topps, (1995) stated that forage legumes increase the total concentration of volatile fatty
xxxiii
acids without affecting the relative proportions and the rumen pH, indicating that forage
legumes are likely to maintain a stable fermentation pattern. Ndlovu and Buchanan-Smith
(1985) found that the feeding of a lucerne supplement increased the proportion of branched
chain volatile fatty acids and suggested that this increase may stimulate the growth of
cellulolytic microorganisms.
The effect of forage legume supplementation on rate of passage of digesta has been studied.
A potential increase in digestibility when these materials are added to poor quality basal diets
may be impaired by a reduction of retention time of digesta, though FCE may be enhanced by
the rise in VFI (Kimambo et al., 1991). Such an effect was observed by Ndlovu and
Buchanan-Smith (1985) when lucerne was fed with maize cobs and by Vanzants and Cochran
(1993) when lucerne was fed at different levels with low quality prairie forage. Similarly,
Manyuchi (1994) found that groundnut hay increased the fractional outflow rate of rumen
solids without altering the pool size of the rumen digesta. He concluded that the increase in
food intake following supplementation with a forage legume was largely facilitated by an
increase in rate of passage of digesta. The mechanism by which this occurs is not fully
understood. The implication of climate may probably play a part. Leng (1990) compiled a
series of data in sheep and cattle fed low-quality forage and supplemented with urea and / or
bypass protein under different climatic conditions. Under tropical conditions, he reported that
supplements which improve the protein: energy (P: E) ratio in nutrients absorbed by cattle fed
low-quality forage reduce metabolic heat production. Where metabolic heat production
would increase body temperature then the animal reduces its feed intake. This reduction in
VFI is ameliorated by the supplement which allows the acetogenic substrate which would
otherwise have to be oxidized, to be partitioned into synthetic reactions with a resultant
decrease in heat production (Leng, 1990). Said and Tolera (1993) fed lambs maize stover as a
basal diet, and three forage legumes, Desmodium intortum, Macrotyloma axillare and
Stylosanthes guianensis, used as supplements at three different levels (250, 350 and 450 g
/head /day). They recorded a high concentration of acetic acid relative to propionic and
butyric acids in all treatment groups. The decrease in heat production with subsequent
reduced body temperature often increased VFI and rumen turnover rate.
2.12 EFFECT OF LEGUME SUPPLEMENTATION ON NUTRIENT UTILIATION
The efficiency with which absorbed nutrients are converted to animal products (live weight,
milk, etc.) is dependent on precisely meeting the animal’s requirements for the individual
xxxiv
nutrients required for the particular function (Preston and Leng, 1987). The P: E ratio is an
important factor that is associated with the efficiency of feed utilization (Devendra, 1995).
Since anaerobic fermentation in the rumen provides the microbial cells which supply the
protein to the animal, the efficiency of microbial growth therefore influences the P : E ratio.
Poor microbial growth due to inadequate dietary N, for example, will result in a low P : E
ratio and, conversely, adequate supplementation and good rumen function enable a good
balance in the nutrients available to the animal (Leng, 1990). Intake has been shown to be
more sensitive to P:E ratio rather than VFA proportions, and legumes have the greatest
potential to alter the former due to higher crude protein (CP) contents and often lower protein
degradation rates caused by tannins (Poppi et al., 1990). In the study by Smith et al. (1989)
referred to earlier, all the three legumes (pigeon pea, cowpea, and lablab) raised ME intake
and increased the intake and retention of N, especially cowpea (p < 0.001) which had the
highest nitrogen content, supporting this theory.
The patterns of feeding of supplements are important for optimizing total nutrient supply. The
availability of N, S or other microbial substrates for maximal rate of fermentation and
microbial growth will depend on the energy substrates being utilized. Where fibrous crop
residues are fed and where the energy is derived from slowly fermented hemicellulose and
cellulose, N, S and other substrates will be needed continuously over the 24 hour feeding
cycle (Dixon, 1986). This author reviewed the effect of different methods of administrating
urea and the use of slow release NPN compounds. In all the reports, the differences in intake
of organic matter (OM) in animals receiving no urea supplement as compared to those
receiving urea once each second day was much greater than the differences among the
methods of urea administration. He concluded that the decision to provide a urea supplement
was far more important than the method of urea administration. In one study by Egan et al.
(1986), mature sheep were fed ad libitum stemmy rye grass hay (N content 0.9%, OM
digestibility 54%) supplemented with 1.5% urea (in aqueous solution sprayed over the hay).
The animals were fed hay along whole lupin grain once a day (150 g per head) or every
second day (300 g per head). Lupin grain supplements increased intake and there was a
tendency for hay intake to be higher (911 g / d) in sheep fed lupins each second day than
those fed lupins each day (808 g / d). The rumen ammonia concentrations were as low as 28
mg /l for the control group but were higher (65-250 mg / l) except on the second day of the 2
day supplemented group when they fell to 47 mg / l. The authors indicated that there is more
to manipulation than identifying individual nutrients lacking and providing these along with
xxxv
the roughage. The variable response in voluntary food intake to tropical legume
supplementation has been attributed to many factors, among which timing of supplementation
may play a part. In a study, cited by Abdulrazak (1995) ad libitum and intermittent feeding of
gliricidia forage were compared. Animals were offered napier grass ad libitum as a basal diet
and supplemented with gliricidia leaves at 300 g daily, 600 g every other day, 900 g once
every three days or ad libitum daily. Restricted feeding of gliricidia affected neither live
weight gains nor feed intake, hence it was suggested that gliricidia could be offered to small
ruminants either daily, every second day, or every third day depending upon the availability
of gliricidia forage and upon feeding practices.
It has been shown that the presence of rumen protozoa reduces the P : E ratio in the nutrients
absorbed (Bird, 1991). In this context, it has been demonstrated that a number of tropical
browse legumes have antiprotozoal properties when supplemented at between 10 and 100 g /
kg diet (Leng et al., 1992a). These include Acacia spp., L. leucocephala, Vigna parteri,
Cassia rotundifolia, Enterolobium cyclocarpium and E. timboura. The use of antiprotozoal
forages has been shown to increase productivity in animals independent of their anti-
protozoan nature due to a greater supply of essential amino acids, and where the basal forage
is high in protein, extra dietary protein becomes available for post-ruminal digestion
(Devendra, 1995).
2.13 ANTI NUTRITIONAL FACTORS FOUND IN TROPICAL LEGUMES
Anti-nutritional factors in food are substances which either by themselves or through
metabolic products in the system, interfere with food utilization or affect the health and
production of animals (Makkar, 1991). Among the several anti-nutritional factors which
cause losses in the livestock industry, tannins, mimosine, cyanogens and nitrates have been
isolated.
Tannins are water soluble phenolic compounds of plants with a molecular weight equal to or
greater than 500 dalton and with the ability to precipitate gelatin and other proteins in
aqueous solution (Mehanso et al., 1987). Hydrolysable tannins (HTs) and condensed tannins
(CTs) are the two types of these compounds which may be differentiated by their structure
and reactivity towards hydrolytic reagents. The main anti-nutritional effects of tannins
present in forage, tree and shrub legumes are: reduction in VFI, diminished digestibility of
nutrients and adverse effects on rumen metabolism.
xxxvi
Van Soest (1994) found a negative correlation between tannin level in vitro, especially CTs
in 40 natural browse plants and their DM digestibility using rumen fluid. High levels of
tannins may slow down the digestion of DM in the rumen, react with the outer cellular layer
of the gut, and thus diminish the permeability of the gut wall (Mira et al., 1983), all of which
would give signals of physical distension, an important feedback signal in the ruminant for
controlling feed intake. The depression in intake could also be due to palatability, since the
tannins in plant tissues may precipitate salivary proteins causing an astringent taste (Kumar
and Horigome, 1986).
The normal pH range in the rumen allows dietary tannins to bind to dietary protein and
digestive enzymes. A reduction of VFA production and microbial protein synthesis as a result
of tannin levels has been reported (Kumar and Singh, 1984). However, the binding effect of
tannins on dietary protein has some merit in that it is protected from degradation in the rumen
and at the low pH condition in the abomasum; the protein is released and becomes available
for digestion in the abomasum and small intestine (Broderick et al., 1991). These authors
reported that the CTs offer advantages over HTs because the relationship between pH and
protein binding is more favourable, and because CTs are more stable and less toxic than HTs.
Generally, tree leaves and browse contain both types of tannin, but HTs have not been found
in any forage legume of agricultural importance (Norton and Poppi, 1995). CTs are found in
many dicotyledonous plants, and particularly in the Leguminosae.
Kumar and D’Mello (1995) reviewed some of the experiments in which tannin-rich forage
(Lotus pedunculatus) and browse (Acacia aneura) legumes were fed to sheep with
polyethylene glycol- 4000 (PEG- 4000) supplementation. Increases in live weight gain and
wool growth were recorded. The tannins bind PEG- 4000 in preference to protein, allowing
dietary protein to be free for digestion. The authors pointed out that using PEG- 4000 in
practice may not be economic at drying (field or oven- drying) of the forage is another means
for inactivation of tannins (Kumar and D’Mello, 1995). Kumar (1992) suggested the
usefulness of feeding browse legumes with non-tannin grasses and urea under farm
conditions.
According to Topps (1992) the most practical alternative would be either to dilute the effect
of tannins by feeding the legume at low levels in a suitable mixture or to feed two or more
rather than one legume species.
2.14 MINERAL CONTENT OF TROPICAL LEGUMES
xxxvii
Tropical legumes generally contain high concentrations of most nutritionally valuable
minerals except sodium (Norton, 1982) (see Table 2.1). However, nutritional requirements
may not always be met, since availability for absorption and function varies with each
element (Norton and Poppi, 1995).
Table 2.1: Mineral content of tropical legumes.
Phosphorus 0.26% Tropical legumes contain approximately 0.22% P
Calcium 1.21% Mean of 154 samples
Magnesium 0.40 Mean of 48 samples
Sodium 0.07 Mean of 60 samples
Copper 10ppm Mean of 14 samples
Zinc 42ppm Mean of 7 samples
Sulphur “Variable” content and “variable” availability in the rumen
Cobalt 0.7 Requirement of 0.11ppm
(Norton, 1982).
The requirements of microorganisms for sulphur (S), phosphorus (P), and magnesium (Mg)
have been reported (Durand and Komisarezuki, 1988). S is essential for the synthesis of S-
amino acids and for microbial protein synthesis. Minimum recommended dietary
requirements are 1.5 g S / Kg DM, which would be met from a diet containing 150 g CP / kg
DM (Norton and Poppi, 1995). The absolute requirement for S is unrelated to CP content of a
diet. Lower levels of S can deplete the microbial pool size and eventually lead to a reduction
in digestibility of the diet.
Orskov (1998) reported that the requirement for S by rumen microbes may be related to the
requirement for N, since the S- containing amino acids comprise a constant proportion of
microbial amino acids. The N: S ratios have been variously estimated, Harrison and McAllan,
(1980) suggested that a ratio of 20: 1 of rumen available N: available S should be satisfactory
while the Agricultural Research Council (1980) recommended value is 14: 1. S deficiency in
livestock is likely to occur in the tropics because of high rainfall and the highly soluble nature
of most natural S salts in the soil (Leng, 1990). Consequently, Hunter et al. (1978) observed
xxxviii
responses to S supplementation in sheep fed Stylosanthes guianensis grown on low S soils
and with N: S ratios as high as 15: 1.
The availability (true absorption) of P in ruminants is estimated as 0.70 of that ingested
(Norton and Poppi, 1995). P deficiency in the rumen will reduce microbial growth efficiency
and in some cases the digestibility and intake of forage (Durand et al., 1986), especially
tropical forages, and it could be severe in grazing animals.
Mg deficiency has also been shown to lead to a reduction in the digestibility and intake of
forage (Wilson and Minson, 1980). Since tropical forages (grasses and legumes) contain
sufficient amounts of Mg, deficiencies in animal grazing tropical pastures are likely to be rare
(Minson and Norton, 1984).
There is comparatively little information available on the content and availability of trace
elements in tropical legume forages, and it is likely that the values reported are more
indicative of the soil types (Norton and Poppi, 1995). Copper (Cu) and cobalt (Co) are the
most commonly measured trace elements reported. Norton and Poppi (1995) indicated that
insufficient data are available for manganese (Mn), zinc (Zn), selenium (Se), iron (Fe), iodine
(I) and possibly molybdenum (Mo), although ruminants have demonstrable requirements for
these elements. Feed Cu concentration is a poor indicator of capacity to meet nutritional
needs because the availability is affected by the presence of other elements (S, Mo, Zn, and
Fe) and the coefficient of absorption (0.01-0.06) is low and varies with season (Norton and
Poppi, 1995). Co is required for the synthesis of vitamin B12 (cyano-cobalamin) in the
rumen, and tropical legumes are a poor source of Co when compared with tropical grasses.
Although the data are limited for Mn and Zn, tropical legumes appear to be adequate sources
of both elements, and deficiencies of these trace elements in grazing animals are rare.
xxxix
CHAPTER THREE
3.0 MATERIALS AND METHOD
3.1 LOCATION OF STUDY
The study was carried out in the Cattle Unit of the Department of Animal Science Teaching
and Research Farm, University of Nigeria, Nsukka. Nsukka lies within longitude 60 45
1 and
70 E and latitude 7
0 12.5
1 N (Offomata, 1975) and on the altitude 447m above sea level. The
climate of the study area is tropical, with relative humidity ranging from 56.01-103.83% and
temperature ranges from 33-370C (Okonkwo and Akubuo, 2007).
The rainy season of Nsukka is between April October and dry season between November
March with annual rainfall range of 1680-1700mm (Agu et al., 2012).
The experiment lasted 104 days comprising 14 days adaptation and 90 days of data
collection.
3.2 EXPERIMENTAL DIETS
Maize stover of Oba Super2 a hybrid variety (Zea mays) was collected from the Department
of Crop Science Farm, University of Nigeria, Nsukka after the maize cobs had been
harvested. The maize stover was allowed to dry in the sun at 10% moisture level. Both the
maize stover and the fresh leaves of Centrosema pubescens was chopped to 6-8mm, then the
xl
maize stover was treated with 5% urea (5kg urea dissolved in 50 litter of water for every
100kg of maize stover) and ensiled in 0.2mm thick polyethylene bags of dimensions 112 cmx
76cm for three weeks. The maize stover was thoroughly hand mixed so that the urea solution
was uniformly mixed with the maize stover. Equal proportions of maize stover and
Centrosema pubescens (1:1 w/w) served as the control Diet A while 50% treated maize
stover plus 50% Centrosema pubescens served as the Diet B.
3.3 EXPERIMENTAL ANIMALS AND MANAGEMENT
Eight N’dama calves between the age of 5 and 8 months were randomly allocated to two
treatments with four calves per treatment. They were housed in individual compartment in the
Cattle Unit of the Department of Animal Science, University of Nigeria, Nsukka Teaching
and Research Farm.
The calves were fed in the morning before they are allowed to go about their normal grazing
and after grazing they are returned back to their individual compartment to continue feeding
on the experimental diets.
All the calves were allowed free access to mineral/vitamin blocks and drinking water ad
libitum. Cleaning of the compartments, removal and weighing of leftovers from previous day
were done daily before supplying each day’s diet. The animals were weighed monthly.
3.4 EXPERIMENTAL DESIGN AND DATA COLLECTION
Eight N’dama calves were randomly assigned into two groups of four calves per group in a
Completely Randomised Design; also each group had two bullocks and two heifers to avoid
error due to sexes.
Xij = µ + Ti + Eij
Where;
µ = Population mean
Ti = Treatment
Eij = Error
The daily feed intake and monthly body weight gain were measured using weighing balance
while the linear body parameters (Body length, Chest girth, Height at withers and Flank to
xli
flank) were measured using tape rule. The feed conversion ratio, dry matter intake and feed
cost/kg gain were calculated as follows:
Feed conversion ratio: feed intake (kg)/Weight gain (kg)
Dry matter intake (g/day): %dry matter/100 x feed intake
Feed cost/kg gain: cost of feed per kg x Feed conversion ratio
Cost analyses
Cost analysis was based on comparison of only feed costs for each animal on the two dietary
treatments. The current feed costs calculated on per kg DM basis were N20 for Diet A and
N30 for Diet B Labour costs for harvesting and gathering the Centrosema pubescens, cost of
chopping maize stover and cost of water for preparing the urea solution were not considered.
Feed cost/Kg gain calculated by multiplying cost of a Kg of the feed with the Feed
Conversion Ratio
Blood samples were also collected from the jugular of the calves with the aid of a syringe
before and after the experiment to determine their blood urea and ammonia levels. The blood
urea was determined using Randox kit as described by Weatherburn (1967), the procedure is
as follows:
Reagent composition
Reagent 1= EDTA---------------------------- 116 mmol/l
Sodium nitroprusside --------- 6 mmol/l
Urease----------------------------- 1g/l
Reagent 2= Phenol (diluted) -------------------- 120 mmol/l
Reagent 3= Sodium hypochlorite (diluted) ----- 27 mmol/l
---------------- Sodium hydroxide--------------------- 0.14 N
Procedure
Pipette 10 µl of sample into test tube and add 100 µl of reagent 1, then mix and incubate at
370c for 10 min. Followed by addition of 2.5 ml each of reagent 2 and reagent 3, mix
xlii
immediately and incubate at 370c for 15 min. finally read the absorbance of the sample after
eight hours.
3.5 CHEMICAL AND DATA ANALYSIS
The proximate composition of the experimental diets was carried out according to A.O.A.C
(2000) methods.
The effects of dietary treatments on different parameters and means were analysed using the
Students T-test at p<0.01.
Table 3.1: Percentage composition of the dietary treatments
Treatments
Parameters Diet A Diet B
Untreated Maize stover 50 -
Urea treated Maize Stover - 50
Centrosema pubescens 50 50
Total 100 100
xliii
CHAPTER FOUR
4.0 RESULTS AND DISCUSSION
4.1 RESULTS
Table 4.1: Proximate composition of diets of treated and untreated maize stover on dry
matter basis.
Parameters Diet A Diet B SEM t Prob Level
Dry matter % 88.7b 83.3
a 0.014 -87.457 0.002**
Crude Protein % 8.16b 10.65
a 0.013 -138.952 0.000**
Ether Extract % 0.71a 0.60b 0.130 5.824 0.028*
Crude Fibre % 43.00a 27.03
b 0.058 157.983 0.000**
Crude Ash % 18.90b 24.27
a 0.015 -240.154 0.000**
Nitrogen Free Extract % 17.93b 20.75
a 0.058 -83.713 0.000**
Where; SEM= Standard Error of Mean, t= T-test
It was observed that there was browning of the urea treated maize stover and it was less
coarse and more pliable than the untreated maize stover.
Diet B had significantly (p<0.05) higher Crude Protein, Crude Ash and Nitrogen Free Extract
but significantly (p<0.05) lower Ether Extract, Crude Fibre and Dry Matter as shown in Table
4.1
Table 4.2: Growth performance of N’dama calves fed urea treated and untreated
maize stover and Centrosema pubescens
Parameters Diet A Diet B SEM t Sig. Level
Initial Weight Kg 89.42 95.58 4.001 -1.041 0.309
Final Weight Kg 104.92b
122.83a
0.415 -1.099 0.003**
Daily Weight gain Kg 0.17b
0.30a
0.003 -33.387 0.000**
Daily Feed Intake Kg 2.59b
3.59a
0.079 -8.815 0.000**
Dry matter intake Kg 2.30b
2.95a
0.066 -6.988 0.000**
FCR 14.39b
11.97a
0.502 3.402 0.003**
Feed cost/Kg gain N 116.07 108.82 14.770 1.203 0.242 Where; SEM= Standard Error of Mean, t= T-test
The growth performance of N’dama calves fed urea treated maize stover and Centrosema
pubescens is presented in Table 4.2
xliv
N’dama calves fed Diet B had significantly (p<0.01) higher Final Weight, Daily Weight
Gain, Daily Feed Intake and Dry Matter intake than calves fed Diet A but had significantly
(p<0.05) lower Feed Conversion Ratio.
Table 4.3: Linear body measurements of N’dama calves fed urea treated and untreated
maize stover and Centrosema pubescens Parameters Diet A Diet B SEM t Prob Level
Chest girth cm 131.00 132.83 1.262 -0.996 0.330
Height at Withers cm 85.00 87.17 1.858 -0.725 0.476
Flank to flank cm 62.58 64.58 1.236 -0.954 0.350 Where; SEM= Standard Error of Mean, t= T-test
There were no significant (p>0.05) differences among the calves fed urea treated and
untreated maize stover diets in all linear body measurements considered (Table 4.3)
Table 4.4: Blood parameters of N’dama calves fed urea treated and untreated maize
stover and Centrosema pubescens
Parameters Diet A Diet B SEM t Prob Level
Urea 38.98 39.75 1.481 -0.320 0.760
Ammonia 0.50b 0.63a 0.033 -2.611 0.040* Where; SEM= Standard Error of Mean, t= T-test
Urea treated maize stover diet (diet B) significantly (p<0.05) increased blood ammonia level
over diet A while blood urea levels were not significantly (p>0.05) different (Table 4.4)
4.2 DISCUSSION
Proximate Composition
The most obvious change in maize stover treated with urea was the colour of the stover.
During the ammoniation procedure, browning of the maize stover occurred and this supports
the earlier work of Saenger et al. (1982). Buettner (1978) demonstrated that the browning of
ammoniated wheat straw occurred at room temperature and was more severe with increasing
rate of ammonia, time of exposure and temperature. The urea treated maize stover was less
coarse and more pliable than the untreated maize stover, this agrees also with the work of
Saenger et al. (1982) and Ali et al. (2012). The increased crude protein content of Diet B was
due to ammoniation of the maize stover in the diet and this supports the findings of Saenger
et al. (1982); Ali et al. (2012), Tesfaye et al. (2005) and Cloete et al. (1983) who reported
increased crude protein of various crop residues when ammoniated. The reduced crude fiber
in Diet B was due to the urea treatment of the maize stover which is in agreement with the
xlv
earlier work of Saenger et al. (1982) and this suggest that the crude fibre becomes more
digestible after treatment with urea.
Feed intake
Daily feed intake of the urea treated maize stover and Centrosema pubescens was 28% higher
than that of the untreated stover and Centrosema pubescens. FAO (1986) stated that urea
treatment may increase voluntary intake of the treated straw by as much as 25 to 30% over
that of the untreated straw. Smith et al. (1989) also reported a significant increase in DMI of
the urea-treated maize stover compared with that of the dry fresh maize stover while Tesfaye,
et al. (2005) reported that dry matter intake of treated maize stover was 22% higher than that
of untreated stover. On the other hand, Saadullah et al. (1982) observed no trend of intake
increment for urea treated rice straw fed to calves. Also according to Munthali et al. (1992),
urea treatment of maize stover did not increase dry matter intake compared with the water
treatment of maize stover.
Generally, the daily feed intakes of N’dama calves in both treatments were above the levels
recommended by Kearl (1982) for animals of comparable live weight to produce a daily
weight gain of 250 to 500 g, though only the daily weight gain of calves fed diet T2 falls
within that range (303g).
Growth Performance
The results of this study is in agreement with the findings of Bui and Le (2001) who reported
considerably higher growth rates for cattle fed ammoniated rice straw than for those fed
untreated straw plus molasses-urea block. These authors attributed such improvements in
growth rate, which was 25% to a 50% increase in dry matter intake of the ammoniated straw.
In the current study, the highly significant weight gain of N’dama calves on the urea treated
maize stover than those on untreated maize stover and Centrosema pubescens could be
attributed to the higher crude protein content of the urea treated maize stover which is in
agreement with the findings of Tesfaye (2006) and Ali et al. (2012) Though the daily dry
matter intake of N’dama calves fed the diet containing untreated stover and Centrosema
pubescens was above the recommended value (Kearl, 1982) that enabled that group of
animals to attain a daily weight gain of about 180g, which was not in agreement with the
report of Tesfaye et al. (2005). These authors reported a daily weight gain of 400g when
crossbred (50% Borana and 50% Friesian) calves of nine to twelve months of age and an
xlvi
average initial live weight of 138.9 kg fed untreated maize stover and natural pasture hay on a
recommended value (Kearl, 1982). This could be due to the lower crude protein content of
the diet and consequently, the lower crude protein intake of the animals and difference in
breeds of cattle.
For every kg live weight gain, N’dama calves on urea treated maize stover and Centrosema
pubescens diet consumed 2.42 kg less feed intake than those N’dama calves on untreated
maize stover and Centrosema pubescenst diet. This finding contradicts the work of Tesfaye et
al. (2005) found (1.8 kg for every kg weight gain), who reported no significant (p>0.05)
difference in the feed conversion ratio of crossbred calves fed urea treated maize stover and
natural pasture hay. Also, this difference was higher than what Li et al. (1993) found (0.91 kg
for every kg weight gain) for crossbred cattle fed ammonia treated maize stover. Similarly,
Zou et al. (1995) found no improvement of 1.6 kg in feed conversion efficiency of young
Holstein cows fed wheat straw ammoniated with urea compared with the efficiency of those
cows fed the untreated straw. The discrepancies among findings of these studies and that of
the current study could be explained by the differences in the type and species of the animals
and the type of the crop residues used in the different studies.
Blood parameters
Both blood ammonia values for T1 and T2 (0.50 and 0.63) falls between the normal range as
previously described by Lee et al. (2008) and Rauprich et al. (2000). The significant
differences in blood ammonia levels was due to urea ammoniation of the maize stovers
xlvii
CHAPTER FIVE
5.0 SUMMARY AND CONCLUSION
Diet B had significantly (p<0.05) higher Crude Protein, Crude Ash and Nitrogen Free Extract
but significantly (p<0.05) lower Ether Extract, Crude Fibre and Dry Matter as shown in Table
4.1 which was due to urea treatment which support the findings of Bui and Le (2001) and
Tesfaye (2006).
N’dama calves fed Diet B had significantly (p<0.01) higher Final Weight, Daily Weight
Gain, Daily Feed Intake and Dry Matter intake than calves fed Diet A but had significantly
(p<0.01) lower Feed Conversion Ratio which is in agreement with Tesfaye et al. (2005) and
Ali et al. (2012).
Urea treated maize stover diet (diet B) significantly (p<0.05) increased blood ammonia level
over diet A while blood urea levels were not significantly (p>0.05) different which is similar
to the report of Lee et al. (2008).
These findings have been achieved as a result of urea treatment. These improvements in
terms of chemical composition and dry matter intake have led to significant higher daily
weight gain of animals fed the diet containing the urea-treated maize stover compared with
that of the animals fed the diet containing the untreated stover.
Therefore, urea ammoniation in general may be considered as one of the strategies that bring
about an efficient utilization of crop residues for livestock feeding especially in Eastern
Nigeria where crop residues constitute the major ruminant feeds.
xlviii
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lxiii
APPENDICES
PROXIMATE COMPOSITION
Moisture
The feed sample should be in a homogenous mixture before carrying out any analysis. To
determine the moisture content of a feed, 2g of feed sample is weighed into a silica dish
which has been previously ignited and weighed. Dry in an oven at 100°c to a constant
weight. Cool in a desiccator each time before taking the weight.
Calculation:
% Moisture = weight of the dish +weight of the feed – weight after drying x100
Weight of the feed taken
Ash
The residue remaining after the destruction of the organic matter of feed is referred to as ash.
Procedure: Wash and dry a crucible in an oven at 100°c cool in a dessicator and weigh it.
Transfer 2g of the feed sample into it. Then, pre-ash using a heater under a fume cupboard.
That is to burn off the less volatile organic matter. Pre –ashing is true when the smoke stops
coming out. Place the crucible in cool muffle furnace. Increase the temperature to 600°c and
maintain this temperature until whitish –grey remains. Cool in desiccators and weigh.
Calculation:
% Ash= weight after ignition –weight of the crucible x 100
Weight of the sample taken
Nitrogen Determination
Principle: Nitrogen in a sample is converted to ammonium-nitrogen by digestion with tetra-
oxo-sulphate (IV) acid using a catalyst. The ammonia librated during the digestion is reacted
with sodium hydroxide and it is removed by steam distillation and collected with boric acid
indicator mixture. This is then titrated with 0.1N HCl to get percentage nitrogen in the
sample.
lxiv
Preparation of sample:
Grind the sample into small particles (i.e. to pass a sieve of 1mm mesh).
Apparatus:
Kjedahl flask – 300ml
Micro kjedahl distillation unit.
Reagents:
Concentrated tetra-oxo-sulphate (iv) acid – 98%
Kjedahl catalyst tabs -3tabs or mixture of sodium sulphate and copper sulphate. The ratio is
3:1 while 4g of the mixture will be used.
Digestion procedure:
Transfer 2g of the sample to a kjedahl flask and add the catalyst tablets or 4g of the mixture
of sodium sulphate and copper sulphate. Add 25 – 30ml concentrated tetra-oxo-sulphate (iv)
acid. Shake gently and take to the heater for digestion. Heat the sample gently at the initial
stage till frothing stops. Then more strongly until a clear solution results.
Determination of Ammonium Nitrogen
Apparatus: Distillation unit – Markham micro distillation type.
Reagents;
Boric acid solution 1%
Methyl red – methyl blue: Dissolve 1.25g of methyl red and 0.825g of methyl blue in 1litre of
ethanol 90%.
Sodium hydroxide 40%
Hydrochloric acid 0.1N
Distillation:
lxv
Steam out the distillation apparatus for 10 minutes. While this is going on make the volume
of your digest up to the mark. Shake the flask properly and pipette 10mls of sample digest
into the unit. Add 10mls of 40% sodium hydroxide into the sample chamber and collect the
liberated ammonia with 10mls boric acid – indicator mixture in a conical flask placed at the
condenser of the markham unit. When the boric acid – indicator mixtures turns green, allow
the distillation to set for another 5mins.
At the end of the time, remove the conical flask and titrate its content with 0.1N hydrochloric
acid unit the original colour of the boric acid – indicator mixture is restored.
Calculation
%N = 0.1 x14.01 x titre value 100 x 100
1000 x wt. sample taken x aliquot
%C.P = N x 6.25.
Determination of Oil
Apparatus:
Extraction thimbles – double thickness 22 x 80mm.
Flat bottomed Flask - 150ml to fit soxhlet extractor.
Heating unit for extraction with a controller for each heating element.
Soxhlet extractors – all glass, of size suitable for the thimbles fitted with condenser.
Reagents:
Cotton wool, Oil – free petroleum ether – boiling range 40°c -60°c or 60°c – 80°c.
Procedure:
Dry a flask in an oven at 100°c, allow it to cool in a desiccators and weigh, transfer 2g
weighed to the nearest mg, of the sample, ground to pass a 1mm mesh sieve, into a thimble
and plug with cotton wool. Place the thimble with its contents into the extractor. Extract with
petroleum spirit for at least 4hrs. Transfer the residue from the thimble to a small mortar,
grind lightly and return it, in the thimble, to the extraction apparatus. Wash out the mortar
lxvi
with a small quantity of petroleum spirit and put the washings to the flask. Continue the
extraction for a further 1hr.
Remove the thimble (see note c) and distil most of the solvent from the flask into the
extractor. Disconnect the flask (see note d), place in an oven at 100°c for 2hrs.Cool in
desiccators and weigh.
Caculation of the result:
Multiply the increase in weight by 100 and divide by the weight of the sample taken. The
result gives the percentage w/w of the oil in the sample.
Determination of crude fibre.
Principle
The organic constituents or the insoluble matter remaining after the feeding stuff has been
treated with sulphuric acid and sodium hydroxide under controlled conditions is known as
fibre. Sample containing more than 3% calcium carbonates are pre- treated with hydrochloric
acid.
Apparatus
Beakers – 500ml borosilicate glass, with round bottomed flasks fitted as condensers, conical
flasks 500ml, borosilicate glass, with cold finger condensers. Boucher funnels, bartley pattern
– three piece, royal Worcester proclaims, plate dial, filter crucibles – 50ml, vetreosil, porosity
11cm whatman No 1 filter paper.
Reagents
Alcohol – industrial methylated spirit is suitable, 1% hydrochloric acid, (they are anti –
foaming reagents), tetra – oxo –sulphate (iv) acid (0.128N), sodium hydroxide (0.313N).
Procedure
Remove the oil from 2gram of the sample ground to pass a 1mm mesh sieve, either by ether
soxhlet extraction or by stirring, settling and decanting three times with petroleum spirit.
Transfer the air dried fat – free material into a flask or beaker (see note a). Add 150 – 200ml
of 0.128N tetra –oxo –sulphate (iv) acid, heat in a heater, allow to boil; then reduce the light
and allow the solution to boil gently for 30minutes. Maintain constant volume by the addition
lxvii
of distilled water. Rotate the container every few minutes to mix the contents and to remove
particles. Fit an 11cm whatman No 1 filter paper into a buchner funnel, pour boiling water
into the funnel and allow to stand until the funnel is hot. At the end of the 30mins boiling,
allow the acid mixture to stand for approximately 1minute and pour into a shallow lever of
hot water.
Adjust the suction so that the filtration of the bulk of the 200ml is completed within 10
minutes. Wash the insoluble matter with boiling water until the ash, washings is neutral to
litmus paper. Wash the residue into a flask or beaker, add 150 – 200ml 0.313N sodium
hydroxide; and then boil for 30 minutes as described above. Allow to stand for approximately
1minute and filter through a filter crucible, using gentle suction. Transfer the whole of the
insoluble material to the crucible. Wash with boiling water several times, add 1% HCl; wash
off with hot water, add alcohol and wash three times with hot water. Dry the crucible and its
contents in oven at 100°C, allow to cool in a desiccator and weigh. Place the crucible in a
cool muffle furnace, increase the temperature to 500°C; maintain this temperature until
ashing is completed. Remove the crucible from the muffle furnace, cool in a desiccator and
weigh.
T-Test
Group Statistics
Treatments N Mean Std. Deviation Std. Error Mean
Body Weight T1
T2
12
12
89.42
95.58
9.558
18.163
2.759
5.243
Chest Girth T1
T2
12
12
131.00
132.83
3.275
5.474
0.945
1.580
Height at withers T1
T2
12
12
85.00
87.17
2.954
9.916
0.853
2.863
Flank to flank T1
T2
12
12
62.58
64.58
1.443
7.115
0.417
2.054
FCR T1
T2
12
12
14.5092
12.0908
1.79053
1.69069
0.51688
0.48806
Feed cost/kg gain T1
T2
12
12
116.0733
108.8175
14.32422
15.21624
4.13505
4.39255
Monthly weight gainT1
T2
12
12
5.33
9.08
1.497
2.429
0.432
0.701
Final weight T1
T2
4
4
96.00
106.50
8.602
17.059
4.301
8.529
Total weight gain T1 4 15.50 0.577 0.289
lxviii
T2 4 27.25 0.500 0.250
Daily weight gain T1
T2
4
4
0.1750
0.3025
0.00577
0.00500
0.00289
0.00250
lxix
Independent samples test
Levene’s Test
for equality of
variances
t-test for equality of means
F Sig t Df Sig
(2-
tailed)
Mean
difference
Std. error
difference
95% Confidence
interval of the
difference
lower Upper
Body weight
equal variance
assumed
Equal variance
not assumed
5.157
0.033
-1.041
-1.041
22
16.658
0.31
0.31
-6.167
-6.167
5.925
5.925
-18.454
-18.687
6.121
6.353
Chest girth
equal variance
assumed
Equal variance
not assumed
3.166
0.089
-0.996
-0.996
22
17.980
0.330
0.333
-1.833
-1.833
1.842
1.842
-5.653
-5.703
1.986
2.036
Height at withers
equal variance
assumed
Equal variance
not assumed
9.890
0.005
-0.725
-0.725
22
17.980
0.476
0.481
-2.167
-2.167
2.987
2.987
-8.361
-8.623
4.028
4.289
Flank to flank
equal variance
assumed
Equal variance
not assumed
14.814
0.001
-0.954
-0.954
22
11.904
0.350
0.359
-2.000
-2.000
2.096
2.096
-6.347
-6.571
2.347
2.571
FCR
equal variance
assumed
Equal variance
not assumed
1.202
0.285
3.402
3.402
\
22
21.928
0.003
0.003
2.41833
2.41833
0.71089
0.71089
0.94403
0.94375
3.89264
3.89292
Feed cost/kg gain
equal variance
assumed
Equal variance
not assumed
0.458
0.506
1.203
22
21.920
0.242
0.242
7.25583
7.25583
6.03267
6.03267
-5.2552
-5.2578
19.76683
19.76947
Monthly weight
gain
lxx
equal variance
assumed
Equal variance
not assumed
2.459
0.131
-4.552
-4.552
22
18.305
0.000
0.000
-3.750
-3.750
0.824
0.824
-5.458
-5.479
-2.042
-2.021
Final weight
equal variance
assumed
Equal variance
not assumed
2.265
0.183
-1.099
-1.099
6
4.433
0.314
0.328
-10.500
-10.500
9.552
9.552
33.874
36.031
12.874
15.031
Total weight gain
equal variance
assumed
Equal variance
not assumed
1.000
0.356
-30.77
-30.77
6
5.880
0.000
0.000
-11.750
-11.750
0.382
0.382
-12.684
-12.689
-10.816
-10.811
Daily weight gain
equal variance
assumed
Equal variance
not assumed
1.000
0.356
-33.39
-33.39
6
5.880
0.000
0.000
-0.12750
-0.12750
0.00382
0.00382
-0.1368
-0.1369
-0.11816
-0.11811
Group statistics
Treatments N Mean Std. Deviation Std. Error
Mean
Feed intake T1
T2
90
90
2.5982
3.5858
0.69615
0.80310
0.07338
0.08465
Dry matter intake T1
T2
90
90
2.3026
2.9538
0.61695
0.63327
0.06503
0.06675
lxxi
Independent samples test
Levene’s Test
for equality of
variances
t-test for equality of means
F Sig t df Sig
(2-
tailed)
Mean
difference
Std. error
difference
95% Confidence
interval of the
difference
lower upper
Feed intake
equal variance
assumed
Equal
variance not
assumed
4.238
0.041
-8.815
-8.815
178
174.484
0.000
0.000
-0.98756
-0.98756
0.11203
0.11203
-1.2086
-1.2087
-0.76647
-0.76644
Chest girth
equal variance
assumed
Equal
variance not
assumed
0.021
0.884
-6.988
-6.988
178
177.879
0.000
0.000
-0.65122
-0.65122
0.09319
0.09319
-0.8351
-0.8351
-0.46732
-0.46732
Group statistics
Treatments N Mean Std. Deviation Std. Error
Mean
Urea T1
T2
4
4
38.975
39.750
4.6764
1.2477
2.3382
0.6238
Ammonia T1
T2
4
4
0.500
0.625
0.0816
0.0500
0.0408
0.0250
lxxii
Independent samples test
Levene’s Test
for equality of
variances
t-test for equality of means
F Sig t df Sig
(2-
tailed)
Mean
difference
Std. error
difference
95% Confidence
interval of the
difference
lower upper
Urea
equal variance
assumed
Equal
variance not
assumed
4.166
0.087
-0.320
-0.320
6
3.425
0.760
0.767
-0.7750
-0.7750
2.4200
2.4200
-6.6966
-7.9632
5.1466
6.4132
Ammonia
equal variance
assumed
Equal
variance not
assumed
0.158
0.705
-2.611
-2.611
6
4.973
0.040
0.048
-0.1250
-0.1250
0.0479
0.0479
-0.2421
-0.2483
-0.0079
-0.0017
lxxiii
Group Statistics
Treatments N Mean Std. Deviation Std. Error
Mean
Ash T1
T2
2
2
8.1600
10.6650
0.01414
0.02121
0.01000
0.01500
Ether extract T1
T2
2
2
0.7050
0.6000
0.02121
0.01414
0.01000
0.01500
Crude fibre T1
T2
2
2
43.000
27.025
0.1414
0.0212
0.1000
0.0150
Crude protein T1
T2
2
2
18.900
24.270
0.01414
0.02828
0.1000
0.2000
Nitrogen free extract T1
T2
2
2
29.000
37.465
0.1414
0.0212
0.1000
0.0150
Moisture content T1
T2
2
2
11.303
16.700
0.1414
0.0212
0.1000
0.0150
lxxiv
Independent samples test
Levene’s Test
for equality of
variances
t-test for equality of means
F Sig t df Sig
(2-
tailed)
Mean
difference
Std. error
difference
95% Confidence
interval of the
difference
lower upper
Ash
equal variance
assumed
Equal
variance not
assumed
-138.9
-138.9
2
1.742
0.000
0.000
-2.50500
-2.50500
0.01803
0.01803
-2.5826
-2.5947
-2.42743
-2.41533
Ether extract
equal variance
assumed
Equal
variance not
assumed
6E+015
0.000
5.824
5.824
2
1.742
0.028
0.038
0.10500
0.10500
0.01803
0.01803
0.02743
0.01533
0.18257
0.19467
Crude fibre
equal variance
assumed
Equal
variance not
assumed
1E+016
0.000
157.98
157.98
2
1.045
0.000
0.003
15.9750
15.9750
0.1011
0.1011
15.5399
14.8138
16.4101
17.1362
Crude protein
equal variance
assumed
Equal
-240.2
2
0.000
-5.37000
0.02236
-5.4662
-5.27379
lxxv
variance not
assumed
-240.2 1.471 0.000 -5.37000 0.02236 -5.5084 -5.23163
NFE
equal variance
assumed
Equal
variance not
assumed
1E+016
0.000
-83.21
-83.71
\
2
1.045
0.000
0.006
-8.4650
-8.4650
0.1011
0.1011
-8.9001
-9.6262
-8.0299
-7.3038
Moisture
content
equal variance
assumed
Equal
variance not
assumed
0.000
134.67
134.67
2
1.054
0.003
0.000
-6.5645
-6.5645
0.03346
0.03346
-5.2555
-5.2578
-7.0299
-8.7647
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