ABSTRACT
The utilization of feed can be affected by the ingredients uesd, processing methods, management and gut microbiota. The growth and nutrient utilization could negatively be affected by deleterious flora like mycotoxins which comes in different forms like ochratoxin, fumosin, and aflotoxin. Some supplements like bentonite has chelating effects on deleterious microbiomes communities. Consequently this research was designed to investigate the effects of bentonite as feed additives for African catfish C.gariepinus. The research also investigated the effects on the growth performances, feed utilization, gut morphology, gut microbial communities and culture water quality of C. gariepinus. To this effect five types of feed were made to vary in composition of bentonite supplements as follows; Feed 1, F1, (35g), Feed F2 (25g), Feed 3 F3(15g),Feed 4,F4( 5g) Feed 5 F5( 0g).The feeds also contains significantly (P<0.05) similar quantities of soyabean meal and fish meal. The basal ingredients comprised of similar quantities of cassava and corn starch blend as binder. Specific quantities of the ingredients were weighed, mixed, pelleted and dried. The feed were used in feeding C. gariepinus of average weight 8-10g stocked at 15 fish per crate for 140days. The results showed that bentonite enhanced feed conversion ratio (FCR), There is a significant different between the FCR of F1 (F1 1.63±0.15) and F5, (F5 2.70±0.11), (P<0.05), weight gain was highest (F1, 52.22±3.65) and F5 (30.91±0.86). Protein efficiency ratio was also significant difference between (F1 1.19±0.10) and F5 (0.57±0.02). The gonadal weight were also significantly higher for catfish fed with F1 (1.49±0.13), followed by those fed with F5 (0.54±0.14). The rate of gut evacuation was reduced by high inclusion of bentonite thus, enhancing proper breakdown and absorption of nutrients. There was positive correlation between increasing inclusion levels of bentonite and feed utilization, growth performances and gonadal developments. Gut microbiota were also improved by bentonite and positively correlated with increasing of bentonite. The results suggest that bentonite optimal inclusion level is (34%). These seem to follow the concept that African catfish is geophargic in nature, bentonite at 34% is recommended for farmers, because results suggest that bentonite supplement is a beneficial additive in catfish diet.
TABLE OF CONTENTS
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table of Contents vi
List of Tables ix
List of Figures x
Abstract xi
CHAPTER 1: INTRODUCTION 1
1.1 Background of the Study 1
1.2 Statement of the Problem 3
1.3 Justification 3
1.4 Objectives 4
1.5 Hypothesis 4
CHAPTER
2: LITERATURE REVIEW 6
2.1 History of Mycotoxins 6
2.2 Food-borne Mycotoxins 6
2.3 Aflatoxins 8
2.4 Contagious
Environment and Mycotoxin Creation in Nourishment 9
2.5 Counteractive
Actions and Control of Mycotoxins in Put Away
Grains and
Seeds 10
2.6 Detecting
Mycotoxins 11
2.7 History
of Bentonite 13
2.8 Application
of Bentonite in Animal Feed Production 14
2.9 Physiochemical
Parameters 17
CHAPTER 3: MATERIALS AND METHODS 20
3.1 Study Area 20
3.2 Fish and Facilities 20
3.3 Experimental Diets and Feeding 20
3.4 Experimental Design 21
3.5 Water Supply and Quality Control 22
3.6 Aquaria Management 22
3.7 Gut Morphology Analysis 22
3.8 Experimental
Procedures 22
3.9 Data Collection 25
3.10 Microbial Analysis 26
3.11 Proximate Analysis 33
CHAPTER 4: RESULTS AND
DISCUSSION 40
4.1 Values of Water Quality Parameters of
Experimental Water 40
4.2 Results of
Proximate Composition (g) of Feeds (f1-f5) Varying in
Bentonite Supplement Used to Fed African Catfish 42
4.3 Results
of Whole Body Composition, Gut Length (cm) and
Weight (g) of Experimental Fish 44
4.4 Results of Gut
Microbiomes of C.gariepinus 49
4.5 Results
of Growth Performance and Feed Utilization C.gariepinus 49
4.6 Results Survival Rate of C.gariepinus 51
4.7 Results of Hepatosomatic Index of C.gariepinus 51
4.8 Results of Waste
Production Ratio of C.gariepinus 52
CHAPTER
5: CONCLUSION AND RECOMMENDATIONS 61
5.1 Conclusion 61
5.2 Recommendations 62
References
LIST OF TABLES
2.1 Mycotoxins
in staple grains and seeds. (IARC, 1993) 7
3.1 Experimental feed composition, and proximate composition of
feed used in feeding of C.
gariepinus Fed with Feeds Varying
Levels of (Bentonite) 24
3.2 Proximate composition of the feed with bentonite at
different level
fed to Clarias gariepunus 25
4.1 Water
quality parameters of holding water for African catfish
(C.gariepinus)
finergings fed with diets f1-f6, varying in
composition of bentonite supplement. 41
4.2 Proximate composition (g) of African catfish C.gariepinus fed with
diets with varying contents of bentonite supplement for 140 days 43
4.3 The Effects of bentonite supplement on the growth and nutritional
performances
of African catfish fed with diets of varying bentonite
inclusion
levels for 140days 48
LIST OF FIGURES
4.1: Effects
of inclusions levels of bentonites on the final average
weight
of African catfish Clarias gariepinus,
fed with diets varying
in
inclusion levels of bentonite for 140days. 53
4.2: Relationship of protein conversion ratio
to the specific growth
rate
of African catfish 54
4.3: The effects of
bentonite inclusion on the gut weight of African
catfish C.gariepinus fed with bentonite supplement diets for
140 days 55
4.4: Effects of
bentonite inclusion level on the gonadosomatic index
of African catfish C.gariepinus fed with bentonite
supplement diets
for 140 days 56
4.5: Effects
of bentonite inclusion on the total fungal count
Aspergilus
spp in the gut of African catfish, C.gariepinus
fed with
bentonite
supplement diets for 140 days 57
4.6: Effects of
bentonite inclusion levels on the gut length of African catfish
Clarias
gariepinus fed with bentonite supplement
diet for 140 days 58
4.7 Effects
of bentonite inclusion levels on the feed conversion ratios
and
waste production ratios of African catfish fed with bentonite
supplemented
diets for 140 days 59
4.8: Effects
of bentonite on waste production ratios of African catfish
Clarias gariepinus fed with bentonite
supplemented diets for
140 days 60
CHAPTER
1
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Aquaculture has been known to be the
rapid growing system in food production system in the world and in Africa,
aquaculture production is expanding rapidly (Brummett et al., 2008; Bostock et al.,
2010), with the culturing of freshwater fish production contributing as the
largest proportion. Aquaculture is
defined to as the culturing of aquatic organisms which includes fish,
crustaceans, aquatic plants and mollusks. These aquatic organisms are been cultured
in fresh, brackish and sea water environments. In 2012, aquaculture production
provides animal protein for human consumption, this figure is assumed to
increase to 62% by 2030 (FAO 2014).
According to FAO, (2012), China is
currently the largest producer of seafood, in the world per capita fish
consumption, particularly from aquaculture, despite the downward revision of
China’s production when it comes to statistical measure in recent years. Fish
and its products as consumed by developed countries are of imports, and owing
to steady demand, thereby declining domestic fishery production, the dependence
on imports, in particular from developing countries, is expected to grow in coming
years (FAO, 2012; Olsen and Hassan, 2012). Fish is a very important source of
protein which contains essential micronutrients for humans, providing over 3.0
billion people with about 20% intake of animal protein. In 2010, fish represents 16.7% of the
worldwide population’s admission of creature protein and 6.5% of all protein
expended. Fish proteins can speak to a urgent wholesome part in some thickly
populated nation where complete protein consumption levels may totally low.
Fish can also provide livelihoods for over 10 million Africans, many of whom
are small-scale operators supplying food to local and sub-regional markets
(Bostock et al., 2010; Munguti et al., 2014; FAO 2014). Despite its
success, aquaculture is faced with some challenges such as feed quality and
water quality which caused poor growth and production.
Aquaculture in Africa is characterized by fast
improvement in freshwater fish cultivating in sub-Saharan Africa, most notably
in Nigeria, Uganda, Zambia, Ghana, South Africa and Kenya, while brackish water
fish farming is found mostly in Egypt. Major cultured fish species includes
African catfish (Clarias gariepinus),
tilapia spp. (mostly Oreochromis
niloticus and O. mossambicus) and
trout (Oncorhynchus mykiss) (Pouomogne
et al.2010, Munguti et al., 2014; FAO, 2014).
The African catfish is one of the most important species currently
farmed in Sub-Sahara Africa (Manuel et al., 2014). C. gariepinus is
mostly found tropical and subtropical fresh waters. C. gariepenus has been widely farmed in heated
waters outside its natural range (Oellermann and Hecht, 2000; Singh et al.,
2012). C. gariepinus has
the ability to grow rapidly at high densities, ability to breathe air and to
withstand poor water quality, and its tasty flesh makes it an excellent
candidate for aquaculture (Manuel et al., 2014).
According to (Schram et al., 2010) C. gariepinus can withstand
plasma, within physiological factors over a
concentrations range of water ammonia concentrations that would be lethal to many
other fishes. However, the high smelling
salts fixation , as uncovered by different parameter affects fish, such as:
plasma glucose, plasma-osmolarity, gill morphology, specific growth rate (SGR),
total feed intake (TFI) and food conversion rate (FCR) which results in low
production.
Hence, management of good
water quality is important for optimum production, specifically for key parameters
such as nitrogenous compounds.
1.2 STATEMENT OF THE PROBLEM
The
use of plant proteins as fishmeal substitute is hampered by anti-nutritional
factor (ANF) such as mycotoxins, phytic acids, non-starch
polysaccharides (NSP) and heavy metals. The ANFs interferes with nutrient
utilization and growth.
Fish farming leads to environmental pollution and degradation of
aquatic ecosystem. Mostly the polluting agents are based on the fish feed used.
Feed ingredients used in feed formulation and the processed feed
are prone to contamination with mycotoxins especially in the tropics.
1.3 JUSTIFICATION
Protein
sources, such as fish meal and soybean meal, are the most expensive components
of formulated feeds, improvement in the efficiency of Nitrogen assimilation and
utilization will improve the social economics of fish production (Reddy et al., 2009; Schram et al., 2010). Fish produce nitrogenous
wastes through catabolism of amino acids. The efficiency of fish nitrogen (N)
assimilation has important implications for water quality and profitability of
fish production. The inherent efficiency
of nutrient utilization by fish implies that nitrogen loading of aquaculture ponds
may be limited by the capacity to assimilate nitrogenous excretion, which may
have an adverse impact on water quality and fish growth. Nitrite and nitrate, which are oxidative products of
ammonia, induced a large variety of physiological
disturbances, in which it has more toxic effect upon accumulation in freshwater fish (Jensen, 2003; Li and Meng, 2010; Tomasso,
2012). Therefore, in order to achieve maximum sustainable
yield in intensive fish culture, maintenance and management of good water
quality is important.
According to Amany (2009), Li et al. (2010), and Slamova et
al. (2011) montmorillonite from bentonite rock can serve as a scrubber
applied directly to adsorb nitrogenous waste and as feed additives to bind
toxins from the gut of the fish.
1.4 OBJECTIVES
i To examine the
effect of bentonite supplement on the growth parameters and the nutrient
utilization of C. gariepinus
ii To
examine effect of bentonite clay on the gut microbial/fungal communities of
C. gariepinus
Iii To
examine the effect of bentonite on the physical and chemical parameters of the
culture water quality
iv To
examine the effect of bentonite on the body composition of the culture
fish
C. gariepinus
1.5 HYPOTHESIS
H0
- Bentonite supplements as feed additive in aqua feeds’ will not improve feed
physical
quality
H1
- Bentonite supplements as feed additive in aqua feeds’ will improve feed
physical quality
H0 - Bentonite supplements as feed
additive in aquafeeds’ will not affect growth and body composition of Clarias garipenus
H1 - Bentonite supplements as feed
additive in aqua feeds’ will affect growth and body
Composition of Clarias garipenus
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