ABSTRACT
An all year round pasture is not always guaranteed in
the tropics especially in Nigeria as half of the period is a dry season.
In order to circumvent the pasture scarcity during drought, silage
making is paramount. In this vein, nutritive value of silage made from
Guinea grass (GG) frequently harvested at 4, 6 and 8 weeks was assessed
by West African dwarf (WAD) goat. Quality and chemical composition of
the silage was assessed. Silage was also fed to WAD goat to determine
the dry matter intake (DMI), Coefficient of preference (COP ) and dry
matter digestibility (DMD). In vitro gas study was also carried out for
the fresh and ensiled grass. Crude protein (CP) from freshly harvested
grass for 4 weeks was (7.00%) and was significantly higher than that of
8weeks (5.70%). While for the ensiled, reduction in Crude protein (CP)
ranged from 5.70% for 8 weeks to 6.57% for 4 weeks. Silage colour, aroma
and texture was normal in all treatment. The temperature ranged from
25.5ºC for 4 weeks and 8 weeks to 26.3ºC for 6 weeks. The pH range from
5.4 for 4 weeks to 5.5 for 6 weeks and 8 weeks. The Dry matter intake
(DMI) ranged from 0.254 for 4 weeks to 0.314 for 6 weeks. The
Coefficient of preference (COP) ranged from 1 for 4 weeks to 1.24 for 6
weeks. Also the Neutral detergent fibre (NDF) ranged from 53.50% for 4
weeks to 58% for 6 weeks. Acid detergent fibre (ADF) ranged from 15% for
4 weeks to 31.5% for 8 weeks. Hemicellulose ranged from 24.5% for 8
weeks to 38.5% for 4 weeks. Organic matter digestibility (OMD) and Short
chain fatty acid(SCFA) increased in 6 and 8 weeks. While Dry matter
digestibility (DMD) increased only in 6 weeks silage. Therefore, silage
is effective in extending the shelf life of forage and making it
available all year round.
TABLE OF CONTENTS
Pages
Title Page --------ii
Abstract--------iii
Acknowledgement-------iv
Certification--------v
Dedication--------vi
Table of contents-------vii
List of Tables--------ix
List of Figures--------x
CHAPTER ONE
INTRODUCTION ------1
1.1 Objectives of the Study-----5
CHAPTER TWO
LITERATURE REVIEW ------6
2.1 Potential of Guinea grass (Panicum Maximum) as
forage in livestock production ---6
2.2Cultivars of Guinea grass----6
2.3Nutritional qualities and chemical composition of Guinea
grass-------7
2.4Effect of stage of growth and frequency of cutting on the
yield and chemical composition of Guinea grass-10
2.5Silage as an alternative source of roughage--12
2.6 Silage fermentation and preservation--13
2.6.1Fermentation process -----13
2.6.2Six Steps during ensiling, storage and feed-out of
fermented forages-----15
2.6.3Additions to silage-----18
2.6.4Addition of water to increase moisture content -19
2.6.5Inhibition of bacteria and mold growth --19
2.6.6"Culturing" silage (inoculants)---20
2.6.7Qualities of a good silage----20
2.7 Grasses ensiled with fresh sugarcane crush--21
2.8History and methodological considerations on in
vitro gas production techniques---23
2.8.1Effect of sample size on in vitro gas production-24
2.8.2Effect of agitation of the medium on in vitro gas
Production------25
2.8.3Effect of changes in atmospheric pressure and of venting
gas during incubation on in vitro gas production-26
2.9Determination of nutritive value of ruminant feeds using
in vitro gas production technique---27
2.10Alternative feed resources by Gas production and rumen
Fermentation in vitro-----28
2.11In vitro digestion, isolation and identification of rumen bacteria
in silage using fermentation technique---31
CHAPTER THREE
MATERIALS AND METHODS---37
3.1Preparation of grass for silage----373.2Determination of silage quality---38
3.3Silage acceptability study----383.4Chemical analysis-----39
3.4.1Moisture content determination ---39
3.4.2Ash determination-----39
3.4.3Crude protein determination----40
3.4.4Neutral Detergent Fibre and Acid Detergent Fibre
Determination------41
3.4.4.1Determination of cell wall fraction (NDF and ADF)-41
3.4.4.2 Composition of the Neutral Detergent Solution-42
3.4.4.3 Composition of Acid Detergent Solution--42
3.4.5In-vitro gas production----43
3.4.6Statistical Analysis-----45
CHAPTER FOUR
RESULTS-------46
CHAPTER FIVE
DISCUSSION------59
CHAPTER SIX
CONCLUSION AND RECOMMENDATION--63
6.1Conclusion------63
6.2Recommendation-----63
REFERENCES-------64
LIST OF TABLES
Table 2.1: Chemical composition of oesophageal samples collected from
sheep grazing Panicum maximum cv gatton pastures at different
levels of maturity during summer, autumn or winter…………………..8
Table 2.2: Six Steps (phases) of silage fermentation and storage………………..18
Table 4.1: Characteristics of ensiled Guinea grass at different ages…………….46
Table 4.2: Coefficient of preference ensiled Guinea grass at different ages…….46
Table 4.3: chemical of composition of fresh and ensiled Guinea grass
harvested at 4, 6 and 8 weeks of age………………………………….47
Table 4.4: Cell wall fraction of fresh and ensiled Guinea grass harvested
at 4, 6 and 8 weeks of age…………………………………………….47
Table 4.5: Volume of gas produced at different hours of incubation by fresh
and ensiled Guinea grass harvested at 4, 6 and 8 weeks of age………48
Table 4.6: Post in vitro fermentation characteristics of fresh and ensiled
Guinea grass harvested at 4, 6 and 8 weeks of age…………………...49
LIST OF FIGURES
Figure 1: Volume of gas produced at different hours by fresh Guinea grass
harvested at 4, 6 and 8 weeks of age………………………………….49
Figure 2: Volume of gas produced at different hours by ensiled Guinea grass
harvested at 4, 6 and 8 weeks of age……………………………………………………… 50
Figure 3: Volume of gas produced at different hours by fresh and ensiled
Guinea grass harvested at 4, 6 and 8 weeks of age.…………………..50
Figure 4: Dry matter (DM) content of fresh and ensiled Guinea grass harvested
at 4, 6 and 8 weeks of age……………………………………………..51
Figure 5: Crude protein (CP) content of fresh and ensiled Guinea grass harvested
at 4, 6 and 8 weeks of age……………………………………………..51
Figure 6: Ash content of fresh and ensiled Guinea grass harvested at 4, 6
and 8 weeks of age……………………………………………………..52
Figure 7: Organic matter (OM) content of fresh and ensiled Guinea grass
harvested at 4, 6 and 8 weeks of age…………………………………..52
Figure 8: Neutral detergent fibre (NDF) content of fresh and ensiled Guinea grass
harvested at 4, 6 and 8 weeks of age…………………………………..53
Figure 9: Acid detergent fibre (ADF) content of fresh and ensiled Guinea grass
harvested at 4, 6 and 8 weeks of age…………………………………..53
Figure 10: Hemicellulose content of fresh and ensiled Guinea grass harvested at
4, 6 and 8 weeks of age………………………………………………54
Figure 11: Volume of methane (CH4) gas produced by fresh and ensiled Guinea
grass harvested at 4, 6 and 8 weeks of age…………………………..54
Figure 12: Dry matter (DMD) content of fresh and ensiled Guinea grass harvested
at 4, 6 and 8 weeks of age……………………………………………55
Figure 13: Organic matter digestibility (OMD) content of fresh and ensiled
Guinea grass harvested at 4, 6 and 8 weeks of age………………….55
Figure 14: Short chain fatty acid (SCFA) content of fresh and ensiled Guinea
grass harvested at 4, 6 and 8 weeks of age………………………..56
CHAPTER ONE
INTRODUCTION
One
of the major physiological disorders of grazing goat in the early wet
season is bloat. In the early wet season, grasses are just coming up,
being tender and with a lot of water in it could results to distention
of the stomach orchestrated by gas accumulation. Also, ruminants
benefits a little from fermentation of over matured grass due to
lignifications. In the light of this, there is need to adequately cater
for all stages of pasture growth in order to meet the normal feed
requirements of ruminants (Babayemi, 2009).
Young pastures are
high in crude protein, low in fibre but very low in dry matter (Bamikole
et al., 2004). On the other hand, older grasses are low in crude
protein but high in fibre and dry matter (Babayemi and Bamikole, 2006).
Young
pastures may be low in fermentable carbohydrates or water soluble
carbohydrates and high buffering solutions or capacities, making them
practically difficult to ensile without injecting additives (Salawu et
al., 2001; Ohba et al., 2004).
Pasture quality decreases from the
young to mature stages as a result of difference in plant composition
between levels of maturity. The presence of an increased proportion of
plants stems, typical of older plants, may restrict access to leafy
parts and force animals to consume lower quality herbage (Reiling et
al., 2001). The quality of available bites is depressed when green leaf
material is scarce and largely dispersed among senescent material
especially in the case of older pasture for which the neutral detergent
fibre (NDF) fractions increased with level of maturity. The nitrogen
content (CP) of pasture also decrease from the young to mature stages.
Increased pasture maturity has a negative effect on the nutritional
value of Panicum maximum (Guinea grass) cv. gatton pasture (Reiling et
al., 2001).
A major constraint to livestock production in
developing countries is the scarcity and fluctuating quantity and
quality of year round forage supply. (Dixon and Egan 1987) reported that
during the dry season, the natural pastures and crop harvest are
usually fibrous and devoid of most essential nutrients which are
required for improved microbial fermentation and improved performance of
the animal. This manifest in loss of weight reduced reproduction
capacity and increased mortality rate. Ensiling is a potent general
method for forage preservation and also a form of treatment to
occasionally salvage the under-utilized pastures for better
acceptability and degradability (Salawu et al., 2001; Ohba et al.,
2004). Silage is one way of improving the utilization of low quality
roughages. Silage production in the tropics is a sustainable means of
supplementing feed for ruminants in the dry season (Babayemi and
Igbekoyi, 2008).
The role of silage is to build up feed reserve
for utilization during period of feed deficiency e.g. dry season or
winter. It also acts as a routine feed supplement to increase
productivity of animals; to utilize excess growth of pasture for better
management and utilization.
Silage making is practiced widely in
intensive animal production system in temperate regions, because during
the winter period, there is no high quality feed available and there is
need to feed high quality feed supplement to complement available grass
in order to improve production and to ensure good conditions for
breeding. Silage making is useful only if the ensiled product is of good
quality, that is well-preserved and of high digestibility and protein
content.
Quality silage is achieved when lactic acid is the
predominant acid produced as it is the most efficient fermentation acid
and will drop the pH of the silage the fastest (Ogunjobi et al., 2010).
The faster the fermentation is completed, the more nutrients will be
retained in the silage. Speed of harvesting, moisture content, length of
chop, silage distribution and compaction can greatly influence the
fermentation process and storage losses. Efficient fermentation ensures a
more palatable and ingestible feed, which encourages optimal dry matter
intake that translates into improved animal performance. It is
important that bacteria responsible for production of acetic and lactic
acid grow and multiply immediately after storing the forage for maximum
quality haulage. Proper packaging of the silage and voiding of air
provides the environment needed by bacteria to break down fibre
components and sugar (Ogunjobi et al., 2010). Oxygen must be removed
from the silage to maximize reproduction of acetic and lactic acid
producing bacteria.
Microbes responsible for fermentation need
anaerobic conditions. As bacteria consume sugars, and product produced
(acetic and lactic acid) cause the pH to drop. Quality silage is
achieved when lactic acid is the predominant acid produced, as it is the
most efficient fermentation acid and will drop the pH of the silage.
The faster the fermentation is completed, the more nutrients will be
retained in the silage. Bacteria inoculants can be added to increase the
number of lactic acid producing bacteria, thus, encouraging more lactic
acid production and a well-preserved forage mass (Ogunjobi et al.,
2010). A critical time during the ensiling process occurs after the
initial three to five days and requires some 15 to 20 days for
completion (Ogunjobi et al., 2010). The success of the ensiling process
is determined during two weeks, during this period there is a gradual
increase in lactic acid producing bacteria which breakdown simple sugars
to accelerate the fermentation process. The resultant effect of this
process is the gradual drop of pH level to a range of 3.8 – 4.2 leading
to further bacterial action.
Harvesting of pasture before
maturity and conserving as silage provides the opportunity of getting
the best for our livestock. Previous studies have reported the effect of
harvesting age on the nutrient composition of grass (Oyenuga and
Olubajo, 1975., Bamikole, et al., 2004). In a situation where grasses
harvested prior to maturity are stored as silage there is a need to know
if the nutrient content can be retained and at what age can this be
best achieved. In this study therefore, the chemical component and
nutritive value of fresh and ensiled Guinea grass harvested at different
stages of maturity was monitored.
Objectives of the Study
The
general objective of this study is to determine the effect of age of
Guinea grass on the silage quality and nutritive value in West African
dwarf goat (WAD).
Specific objectives of this study are;
To determine the chemical composition of silage produced from Guinea grass harvested at different age.
To determine the in vitro gas production characteristics of ensiled Guinea grass at different ages.