ABSTRACT

This study was carried out to evaluate the growth of Heterobranchus longifilis fed artificial feed coated with isolates of bacteria from the gut of Oreochromis niloticus. The bacteria isolated were Bacillus, Pseudomonas and Candida. Different concentrations of the isolates (1×10⁷, 5×10⁸ and 1×10⁹ colony-forming units per gram (cfu/g) were used to coat pellets of a commercial feed. Juvenile H. longifilis of mean weight 3.25g, at a stocking density of one fish/10 litres of water, were then fed the coated pellets. Fish were fed 6% fresh body weight thrice daily. The experiment was conducted as a 3 x 3 x 4 completely randomized design in a factorial experiment. Weight and length of fish were determined monthly, and feed weight adjusted. The proximate compositions of the feeds were determined. Initial and final proximate composition of the fish flesh was determined. Data collected was analyzed using ANOVA. Means were separated using Fisher’s LSD. There was significant difference (P<0.05) in the growth performance and nutrient utilization parameters across concentrations. H. longifilis  fed artificial feed coated with different concentrations of bacteria isolates had negative allometric growth except for Candida at 1 x 10⁹ that had posistive allometry. The crude protein composition of fish flesh analysed at the end of the study was significantly different (P<0.05) among the treatments.  Candida gave the best result in terms of enhancing growth in H. longifilis.  Candida at 1 x10⁹ cfu/g gave the highest mean weight (1524g mean weight).  This was followed by Candida at 5 x10⁸ cfu/g (mean weight 1208g) and Candida at 1 x10⁷ cfu/g (mean weight 1201g).  The highest weight realized with Pseudomonas and Bacillus was 1085g and 989g at 1x10⁷ cfu/g and 1 x10⁹ cfu/g respectively. Histomorphological variables namely, height of mucosa, thickness of muscularis, microvilli length, thickness of epithelium layer and number/size of globelet cells in the digestive tract of H. longifilis were significantly (P<0.05) different among concentrations between species. Feed performance and nutrient utilization analyzed from protein efficiency ratio, feed conversion ratio and feed conversion efficiency were significantly different (P<0.05) among the treatments. At the end of the study period, it was observed that Bacillus 5 x 10⁸ had the best FCRCUM (5.94) while Pseudomonas 1 x 10⁷ had the worst FCRCUM (6.92). Bacillus 5 x 10⁸ also had the highest FCECUM (16.92) and Pseudomonas 1 x 10⁷ had the lowest FCECUM (14.5). For PERCUM, Bacillus 1 x 10⁷ and 1 x 10⁹ were the highest (0.36) while Candida 1 x 10⁷, 1 x 10⁹ and Pseudomonas 1 x 10⁷ was the least (0.27). There was no significant difference in the water quality parameters among the experimental units during the study. The growth performance, health status, survival rate, nutrient utilzation, fish wellbeing and water quality can be improved by feeding fish with feed coated Candida at 1×10⁹ cfu/g. It can be deduced from this research that feed coated with Bacillus, Pseudomonas and Candida species can be used as a fish feed additive in catfish H. longifilis culture to enhance growth response and health. 

TABLE OF CONTENTS

                                                                                                                        Page

Title                                                                                                                             i

Declaration                                                                                                                  ii

Certification                                                                                                                iii

Dedication                                                                                                                  iv

Acknowledgements                                                                                                    v

Table of Contents                                                                                                       vi

List of Tables                                                                                                              xiii

List of Figures                                                                                                             xvii

List of Plates                                                                                                               xx

Abstract                                                                                                                      xxii

CHAPTER 1:                        INTRODUCTION

1.1       Background of the Study                                                                               1

1.2       Definition of Probiotics                                                                                  2

1.3       Uses of Probiotics                                                                                           3

1.4       Mechanism of Probiotics                                                                                4

1.5       Statement of the Problem                                                                               4

1.6       Justification of the Study                                                                               5         

1.7       Objectives of the Study                                                                                 6

CHAPTER 2:                        LITERATURE REVIEW

2.1       History of Probiotics                                                                                       7

2.2       Aquaculture and Probiotics                                                                            9

2.3       Fish Wellbeing                                                                                                9

2.4       Inclusion Methods of Digestive Tract Isolates of Oreochromis

niloticus in Artificially available Pelleted Feed for Fish                                 11

2.4.1    Storage of Fish Feed Coated with Isolates from the Digestive Tract of O.

Niloticus                                                                                                          12

2.5       Classification of Probiotics                                                                             12

2.5.1    Feed probiotics                                                                                               12

2.5.2    Water probiotics                                                                                              13

2.6       Mode of Action of Probiotics                                                                         13

2.6.1    Competition for adhesion sites and colonization                                            14

2.6.2    Competition for nutrient and energy sources                                                 15

2.7       The Role of Probiotics in Digestion Enhancement and Growth                    16

2.8       Importance of Fish Gastro-Intestinal Tract (GIT) Micro-biota                      24

2.9       Influence of Probiotics on Water Quality Parameters                                    26

2.10     Dosages of Microbial Isolates use in Coating Artificially available Pellets    27

2.11     Duration of Feeding Microbial Isolates Coated on

Artificially available Pellets                                                                            28

2.12     Effect of Probiotics on the Microbial Load of Digestive Tract and

Culture Medium                                                                                              29

2.13     Classification and Description of Heterobranchus longifilis                          33

2.13.1  The identification keys for H. longifilis                                                          34

2.13.2  Ecology and physiology of H. longifilis                                                         34

2.14     Identification Key for Source Bacteria Isolate                                               35

CHAPTER 3:                        MATERIALS AND METHODS

3.1       Study Area                                                                                                      36

3.2       Experimental Design                                                                                       36

3.3       Experimental Procedure                                                                                  37

3.4       Isolation, Identification and Cultivation of Microorganisms                         38

3.4.1    Isolation of micro-organism                                                                            38

3.4.2    Culture techniques                                                                                          39

3.4.3    Gram staining technique and microscopy                                                       40

3.4.4    Total aerobic plate count                                                                                 41

3.4.5    Biochemical tests                                                                                            41

3.4.5.1 Coagulase test                                                                                                 42

3.4.5.2 Oxidase test                                                                                                    42

3.4.5.3 Indole test                                                                                                       42

3.4.5.4 Citrate test                                                                                                      43

3.4.5.5 Sulphate reduction                                                                                          43

3.4.5.6 Catalase test                                                                                                    43

3.4.5.7 Urease test                                                                                                      44

3.4.5.8 Methyl red test                                                                                                44

3.4.5.9 Voges-proskauer test                                                                                      44

 3.4.5.10 Triple sugar iron test                                                                                   44

3.4.5.11 Motility test                                                                                                  45

3.5       Preparation of Probiotic Culture                                                                     45

3.6       Coating of Bacteria Isolate on Fish Feed                                                       45

3.7       Growth Performance Indices                                                                          46

3.7.1    Weight gain                                                                                                     46

3.7.2    Specific growth rate                                                                                        46

3.7.3    Percentage weight gain                                                                                   46

3.7.4        Protein efficiency ratio (PER) was calculated using the relationship             47

3.7.5                                                                                                        47

3.7.6    Length-weight relationship                                                                             47

3.8       Proximate Analysis of Feed and Fish                                                             48

3.9       Microbial Analysis of Culture Water and Digestive Tract of H. longifilis     48

3.10     Histomorphology of Digestive Tract of H. longifilis Fed Artificial

Pellets Coated with Bacillus, Pseudomonas and Candida Species                49

3.12     Statistical Analysis                                                                                          49

CHAPTER 4:                        RESULTS AND DISCUSSION

4.1       Growth Performance of H. longifilis Fed Artificial Pellets Coated

            with Bacillus, Pseudomonas and candida Species                                         51

4.1.1    Growth performance and nutrient utilization of H. longifilis fed

            artificial pellets coated with varying concentrations of bacteria

            isolates across the months                                                                               51

4.2       Growth Performance and Nutrient Utilization of H. longifilis Fed

Artificial Pellets Coated with of Varying Species of Bacteria Isolate

from the gut of O. niloticus for each Concentration across the Months         95

4.3       Wellbeing of H. longifilis fed Artificial Pellets Coated with Different

            Bacteria Isolates from the Gut of O. niloticus                                                138

4.3.1    Total weight, total length, allometric growth pattern (b), scaling

            constant (a), coefficient of correlation (r) and coefficient of

determination (R²) of H longifilis fed artificial pellets coated with

varying concentrations of isolates from the    gut of O. niloticus                   138

4.4       Histomorphology of Digestive Tract of H. longifilis fed with Artificial

Pellets Coated with Bacillus, Pseudomonas and Candida Species                140

4.4.1    Thickness of muscularis (MU) (µm) of digestive tract of H.

            longifilis fed artificial pellets coated with Bacillus, Pseudomonas and

            Candida species                                                                                              153

4.4.2    Average height of mucosa (M) (µm) of digestive tract of H. longifilis

fed artificial pellets coated with Bacillus, Pseudomonas and Candida

species                                                                                                             155

4.4. 3   Microvilli length (MV) (µm) of digestive tract of H. longifilis fed

artificial pellets coated with Bacillus, Pseudomonas and Candida species    157

4. 4. 4  Epithelium layer thickness (EL) (µm) of digestive tract of H. longifilis

            fed artificial pellets coated with Bacillus, Pseudomonas and Candida

            species                                                                                                             159

4.4. 5   Number of goblet cells (GC No) of digestive tract of H. longifilis

fed artificial pellets coated with Bacillus, Pseudomonas and

Candida Species                                                                                             161

4.4. 6   Size of goblet cell (GC size) (µm) of digestive tract of H. longifilis fed

artificial pellets coated with Bacillus, Pseudomonas and Candida Species   163

4.5       Correlation of Growth Parameters and Histomorphological Indices of

            H. longifilis Fed artificial Pellets Coated with Bacillus,

Pseudomonas and Candida Species                                                               165

4. 5. 1 Correlation of growth parameters and histomorphological indices of

            H. longifilis fed artificial pellets coated with Bacillus species at (1×10⁷)       165

4.5.2    Correlation of growth parameters and histomorphological indices of H.

            longifilis fed artificial pellets coated with Psuedomonas species (5×10⁸)      167

4.5.3    Correlation of growth parameters and histomorphological indices of H.      

            longifilis fed with artificial pellets coated with Candida species (1×10⁹)      169

4.6       Proximate Composition of Artificial Fish Pellets Coated with Bacillus,

Pseudomonas and Candida Species                                                               171                 

4.6.1    Dry matter of artificial pellets coated with Bacillus, Pseudomonas

and Candida species                                                                                       171

4.6.2    Moisture content of artificial pellets coated with Bacillus,

Pseudomonas and Candida species                                                                173

4.6.3    Crude protein content of artificial pellets coated with Bacillus,

            Pseudomonas and Candida species                                                               175

4.6.4    Crude fat content of artificial pellets coated with Bacillus,

Pseudomonas and Candida species                                                                177

4.6.5    Ether extract of artificial pellets coated with Bacillus,

Pseudomonas and Candida species                                                                179

4.6.6    Ash content of artificial pellets coated with Bacillus,

Pseudomonas and Candida species                                                                181

4.6.7    Nitrogen free extract of artificial pellets coated with Bacillus,

Pseudomonas and Candida species                                                               183

4.7       Proximate Composition of H. longifilis Fed Artificial Pellets Coated

with Bacillus, Pseudomonas and Candida Species                                        185

4.7.1   Crude protein content of H. longifilis fed artificial pellets coated with 

Bacillus, Pseudomonas and Candida species                                                 185

4.7.2    Dry matter of H. longifilis fed artificial pellets coated with Bacillus,

Pseudomonas and Candida species                                                                187

4.7.3    Moisture content of H. longifilis fed with artificial pellets coated

with Bacillus, Pseudomonas and Candida species                                         189

4.7.4    Ash content of H. longifilis fed with artificial pellets coated with

Bacillus, Pseudomonas and Candida species                                                 191

4.7.5    Ether extract content of H. longifilis fed with artificial pellets coated

with Bacillus, Pseudomonas and Candida species                                         193

4.7.6    Nitrogen free extract content of   H. longifilis fed artificial pellets

coated with Bacillus, Pseudomonas and Candida species                             195

4.7.7     Metabolizable energy content of H. longifilis fed artificial pellets

            coated             with Bacillus, Pseudomonas and Candida species                             197

4.8       Correlation of Proximate Composition Indices and histomorphological

            Variables of H. longifilis Fed Commercial Pellets Coated

            with Bacillus, Pseudomonas   and Candida Species                                      199

4.8.1    Correlation of proximate composition indices and histomorphological

variables of H. longifilis fed artificial pellets coated with

Bacillus species (1×10⁷)                                                                                  199

4.8.2    Correlation of proximate composition indices and histomorphological

variables of H. longifilis fed artificial pellets coated with

Psuedomonas species (5×10)                                                                          201

4.8.3    Correlation of proximate composition indices and histomorphological

variables of H. longifilis fed with artificial pellets coated with  

Candida species    (1×10⁹)                                                                              203

4.9       Water Quality of Culture tanks of H. longifilis Fed Artificial Pellets

Coated with Bacillus, Pseudomonas and Candida Species                           205

4.10     Microbial Load of Rearing Water and Digestive Tract of H. longifilis

            Fed Commercial Pellets Coated with Bacillus, Pseudomonas and

            Candida Species                                                                                             207

4.10.1  Microbial load of digestive tract of H. longifilis fed artificial pellets

            coated             with Bacillus, Pseudomonas and Candida species                             207

4.10.2  Microbial loads of water used in culturing H. longifilis fed artificial

pellets coated with Bacillus, Pseudomonas and Candida species                  209

4.11     Discussion                                                                                                       211

4.11.1  Growth performance of H. longifilis fed artificial feed pellets

            coated with isolates of the major bacteria species from gut of O.

            niloticus                                                                                                           211

4.11.2  Feed performance and nutrient utilization of H. longifilis fed artificial

feed pellets   coated with isolates of the major bacteria species from

digestive tract of O. niloticus                                                                          214

4.11.3  Wellbeing of H. longifilis fed artificial pellets coated with different

bacteria isolates from the gut of O. niloticus                                                  218

4.11.4  Physico-chemical parameters of water used in grow-out of H. longifilis

fed artificial feed pellets coated with isolates of the major bacteria

species in gut of O. niloticus                                                                           220

CHAPTER 5:                        CONCLUSION AND RECOMMENDATIONS

5.1       Conclusion                                                                                                      222

5.2       Recommendations                                                                                          222

References                                                                                                      224

LIST OF TABLES

4.1.0:   Growth performance and nutrient utilization of H. longifilis fed

artificial pellets coated with varying concentrations of Bacillus

after first month of culture                                                                             53

4.1.1:   Growth performance and feed utilization of H. longifilis fed artificial

pellets coated with varying concentrations of Pseudomonas after first

month of culture                                                                                             55

4.1.2:   Growth performance and nutrient utilization of H. longifilis

fed artificial pellets coated with varying concentrations of Candida

after the first month of culture                                                                       57

4.1.3:   Growth performance and nutrient utilization of H. longifilis

fed artificial pellets coated with varying concentrations of Bacillus

after second month of culture                                                                         59

4.1.4:   Growth performance and nutrient utilization of H. longifilis fed                               artificial pellets coated with varying concentrations of Pseudomonas                        after second month of culture                                                                         61

4.1.5:   Growth performance and nutrient utilization of H. longifilis

fed artificial pellets coated with varying concentrations of Candida

 after the second month of culture                                                                  63

4.1.6:   Growth performance and nutrient utilization of H. longifilis

fed artificial pellets coated with varying concentrations of Bacillus

after third month of culture                                                                            65

4.1.7:   Growth performance and nutrient utilization of H. longifilis fed

artificial pellets coated with varying concentrations of Pseudomonas

after third month of culture                                                                            67

4.1.8:   Growth performance and nutrient utilization of H. longifilis fed

artificial pellets coated with varying concentrations of Candida after

three month of culture                                                                                               69

4.1.9:   Growth performance and nutrient utilization of H. longifilis fed

artificial pellets coated with varying concentrations of Bacillus after           

fourth month of culture                                                                                  71

4.1.10: Growth performance and nutrient utilization of H. longifilis fed

artificial pellets coated with varying concentrations of

Pseudomonas after four month of culture                                                      73

4.1.11: Growth performance and nutrient utilization of H. longifilis fed

artificial pellets coated with varying concentrations of Candida after

the fourth month of culture                                                                            75

4.1.12: Growth performance and nutrient utilization of H. longifilis fed

artificial pellets coated with varying concentrations of Bacillus after

the fifth month of culture                                                                               77

4.1.13: Growth performance and nutrient utilization of H. longifilis fed

artificial pellets coated with varying concentrations of Pseudomonas

the after fifth month of culture                                                                       79

4.1.14: Growth performance and nutrient utilization of H. longifilis fed

artificial pellets coated with varying concentrations of Candida after

the fifth month of culture                                                                               81

4.1.15: Growth performance and nutrient utilization of H. longifilis fed

artificial pellets coated with varying concentrations of Bacillus after           

sixth month of culture                                                                                     83

4.1.16: Growth performance and nutrient utilization of H. longifilis fed

artificial pellets coated with varying concentrations of Pseudomonas

after sixth month of culture                                                                            85

4.1.17: Growth performance and nutrient utilization of H. longifilis fed

artificial pellets coated with varying concentrations of Candida after

sixth month of culture                                                                                     87

4.1.18: Growth performance and nutrient utilization of H. longifilis fed

artificial pellets coated with varying concentrations of Bacillus after           

seventh month of culture                                                                                89

4.1.19: Growth performance and nutrient utilization of H. longifilis fed

artificial pellets coated with varying concentrations of Pseudomonas

after seventh month of culture                                                                        92

4.1.20: Growth performance and nutrient utilization of H. longifilis fed

artificial pellets coated with varying concentrations of Candida after

seventh month of culture                                                                                94

4.2:      Total weight, total length, allometric growth pattern (b), scaling

constant (a), coefficient of correlation (r) and coefficient of

determination (R²) of H longifilis fed artificial pellets coated

with varying concentrations of isolates from the gut of O. niloticus              139

4.3:      Thickness of muscularis (MU) (µm) of digestive tract of H. longifilis fed                 artificial pellets coated with Bacillus, Pseudomonas and Candida species     154

4.4:      Average height of mucosa (M) (µm) of digestive tract of H. longifilis

fed artificial pellets coated with Bacillus, Pseudomonas and

Candida species                                                                                              156

4.5:      Microvilli length (MV) (µm) of digestive tract of H. longifilis

fed artificial pellets coated with Bacillus, Pseudomonas and

Candida species                                                                                              158

4.6:      Epithelium layer thickness (EL) (µm) of digestive tract of H. longifilis fed

artificial pellets coated with Bacillus, Pseudomonas and Candida species    160

4.7:      Number of goblet cell (GC No) of digestive tract of H. longifilis fed

artificial pellets coated with Bacillus, Pseudomonas and Candida species    162

4.8:      Size of goblet cell (GC size) (µm) of digestive tract of H. longifilis fed

artificial pellets coated with Bacillus, Pseudomonas and Candida species    164

4.9:      Correlation matrix of growth parameters and histomorphological indices

of H. longifilus fed artificial pellets coated with Bacillus species (1×10⁷)     166

4.10:    Correlation matrix of growth parameters and histomorphological indices

            of H. longifilis fed artificial pellets coated with Psuedomonas species

(5×10⁸)                                                                                                            168

4.11:    Correlation matrix of growth parameters and Histomorphological

indices of H. longifilis fed artificial pellets coated with Candida

species (1×10⁹)                                                                                                170

4.12:    Dry matter of artificial pellets coated with Bacillus, Pseudomonas                           and Candida species at concentration of 1×10⁷, 5×10⁸ and 1×10⁹ cfu ml^-1                 respectively, after seven months of culture                                                    172

4.13:    Moisture content of commercial pellets coated with Bacillus,

Pseudomonas and Candida species at concentration of 1×10⁷, 5×10⁸

and 1×10⁹ cfu ml^-1 respectively, after seven months of culture                      174

4.14:    Crude protein content of artificial pellets coated with Bacillus,

Pseudomonas and Candida species at concentration of 1×10⁷, 5×10⁸

and 1×10⁹ cfu ml^-1 respectively, after seven months of culture                      176

4.15:    Crude fat content of artificial pellets coated with Bacillus,

Pseudomonas and Candida species at concentration of 1×10⁷, 5×10⁸

and 1×10⁹ cfu ml^-1 respectively, after seven months of culture                      178

4.16:    Ether extract of artificial pellets coated with Bacillus, Pseudomonas

and Candida species                                                                                       180

4.17:    Ash content of artificial pellets coated with Bacillus, Pseudomonas

and Candida species                                                                                       182

4.18:    Nitrogen free extract of artificial pellets coated with Bacillus,

Pseudomonas and Candida species                                                                184

4.19:    Crude protein content of H. longifilis fed artificial pellets coated

with Bacillus, Pseudomonas and Candida species                                         186

4.20:    Dry matter of H. longifilis fed with artificial pellets coated with

Bacillus, Pseudomonas and Candida species                                                 188

4.21:    Moisture content of H. longifilis fed with artificial pellets coated

with Bacillus, Pseudomonas and Candida species                                         190

4.22:    Ash content of H. longifilis fed artificial pellets coated with Bacillus,          Pseudomonas and Candida species                                                             192

4.23:    Ether extract content of H. longifilis fed commercial pellet coated

with Bacillus, Pseudomonas and Candida species                                         194

4.24:    Nitrogen free extract content of H. longifilis fed artificial pellets

coated with Bacillus, Pseudomonas and Candida species                             196

4.25:    Metabolizable energy content of H. longifilis fed artificial pellets

coated with Bacillus, Pseudomonas and Candida species                             198

4.26:    Correlation matrix of proximate composition indices and

histomorphological variables of H. longifilis fed artificial pellets      

coated with Bacillus species in 1×10⁷                                                                                 200

4.27:    Correlation matrix of proximate composition indices and

histomorphological variables of H. longifilis fed artificial pellets

coated with Psuedomonas species (5×10⁸)                                                     202

4.28:    Correlation matrix of proximate composition Indices and

histomorphological variables of H. longifilis fed with artificial pellets

coated with Candida species (1×10⁹)                                                             204

4.29:    Water quality of culture tanks of H. longifilis fed artificial pellets

coated with Bacillus, Pseudomonas and Candida species                             206

4.30:    Microbial load of digestive tract of H. longifilis fed artificial pellets

            coated with Bacillus, Pseudomonas and Candida species (cfu/g)                 208

4.31:    Microbial load of water used in culturing H. longifilis fed artificial                          pellets coated with Bacillus, Pseudomonas and Candida species (cfu/ml)            210

                                                             LIST OF FIGURES                                               

4.1:      Growth performances and nutrient utilization of H. longifilis fed

artificial pellets coated at concentration of (1 x 10⁷), with Bacillus,

Pseudomonas and Candida from the gut of O. niloticus after the

first month of culture.                                                                                     97

4.2:      Growth performances and nutrient utilization of

Heterobranchus longifilis fed artificial pellets coated at concentration

of (5 x 10⁸), with Bacillus, Pseudomonas and Candida from the

gut of O. niloticus after the first month of culture.                                        99

4.3:      Growth performances and nutrient utilization of

Heterobranchus longifilis artificial pellets coated at concentration

of (1 x 10⁹), with Bacillus, Pseudomonas and Candida from the

gut of O. niloticus after the first month of culture                                         101

4.4:      Growth performances and nutrient utilization of

Heterobranchus longifilis fed artificial pellets coated at

concentration of (1 x 10⁷), with Bacillus, Pseudomonas and Candida

from the gut of O. niloticus after the second   month of culture                    103

4.5:      Growth performances and nutrient utilization of

Heterobranchus longifilis fed artificial pellets coated at concentration

of (5 x 10⁸), with Bacillus, Pseudomonas and Candida from the gut of

O. niloticus after the second month of culture.                                              105

4.6:      Growth performances and nutrient utilization of

Heterobranchus longifilis fed artificial pellets coated at concentration

of (1 x 10⁹), with Bacillus, Pseudomonas and Candida from the gut of

O. niloticus after the second   month of culture.                                            107

4.7:      Growth performances and nutrient utilization of

Heterobranchus longifilis fed artificial pellets coated concentration

of (1 x 10⁷), with Bacillus, Pseudomonas and Candida from the gut of

O. niloticus after the third month of culture                                                   109

4.8:      Growth performances and nutrient utilization of Heterobranchus

longifilis fed artificial pellets coated at concentration of (5 x 10⁸)

with Bacillus, Pseudomonas and Candida from the gut of O. niloticus

after the third month of culture.                                                                     111

4.9:      Growth performances and nutrient utilization of Heterobranchus longifilis

fed artificial pellets coated at concentration of (1 x 10⁹) with Bacillus,

Pseudomonas and Candida from the gut of O. niloticus after the third

month of culture.                                                                                            113

4.10:    Growth performances and nutrient utilization of Heterobranchus longifilis

fed artificial pellets coated at concentration of (1 x 10⁷,) with Bacillus, Pseudomonas and Candida from the gut of O. niloticus after the fourth

month of culture                                                                                             115

4.11:    Growth performance and nutrient utilization of Heterobranchus longifilis

fed artificial pellets coated at concentration of (5 x 10⁸) with Bacillus,

Pseudomonas and Candida from the gut of O. niloticus after the fourth

month of culture                                                                                             117

4.12:    Growth performance and nutrient utilization of Heterobranchus longifilis

fed artificial pellets coated at concentration of (1 x 10⁹) with Bacillus,

Pseudomonas and Candida from the gut of O. niloticus after the fourth

month of culture                                                                                             119

4.13:    Growth performances and nutrient utilization of Heterobranchus longifilis

fed artificial pellets coated at concentration of (1 x 10⁷,) with Bacillus, Pseudomonas and Candida from the gut of O. niloticus after the fifth

month of culture.                                                                                            121

4.14:    Growth performance and nutrient utilization of Heterobranchus longifilis

fed artificial pellets coated at concentration of (5 x 10⁸,) with Bacillus, Pseudomonas and Candida from the gut of O. niloticus after the fifth

month of culture                                                                                             123     

4.15:    Growth performance and nutrient utilization of Heterobranchus longifilis

fed artificial pellets coated at concentration of (1 x 10⁹,) with Bacillus, Pseudomonas and Candida from the gut of O. niloticus after the fifth

month of culture                                                                                             125

4.16:    Growth performances and nutrient utilization of Heterobranchus

longifilis fed artificial pellets coated at concentration of (1 x 10⁷),

with Bacillus, Pseudomonas and Candida from the gut of O. niloticus

            after the sixth month of culture.                                                                     127

4.17:    Growth performances and nutrient utilization of Heterobranchus

longifilis fed artificial pellets coated at concentration of (5 x 10⁸,)

with Bacillus, Pseudomonas and Candida from the gut of O. niloticus

after the sixth month of culture                                                                      129

4.18:     Growth performances and nutrient utilization of Heterobranchus

longifilis fed artificial pellets coated at concentration of (1 x 109,)

with Bacillus, Pseudomonas and Candida from the gut of O. niloticus

after the sixth month of culture.                                                                     131

4.19:    Growth performance and nutrient utilization of Heterobranchus

longifilis fed artificial pellets coated at concentration of (1 x 107)

with Bacillus, Pseudomonas and Candida from the gut of O. niloticus

after the seventh month of culture.                                                                 133

4.20:     Growth performance and nutrient utilization of Heterobranchus longifilis

fed artificial pellets coated at concentration of (5 x 108) with Bacillus,

Pseudomonas and Candida from the gut of O. niloticus after the

seventh month of culture.                                                                               135

4.21:    Growth performances and nutrient utilization of Heterobranchus

longifilis fed artificial pellets coated at concentration of (1 x 109)

with Bacillus, Pseudomonas and  Candida  from the gut of O. niloticus

after the  seventh month of culture                                                                 137

LIST OF PLATES

2.1:      Heterobranchus longifilis   Valenciennes. 1840                                              35

4.1:      Histomorphology of H. longifilis digestive tract showing microvilli,

mucosa, muscularis, goblet cell and epithelium layer before feeding

commercial pellets coated with Bacillus, Pseudomonas and

Candida species. (Hematoxyline, eosin) (X 1000)                                         142

4.2:      Microvilli, mucosa, muscularis, goblet cell and epithelium layer of H.

longifilis digestive tract after seven months of feeding with artificial

feed pellets coated with Bacillus species obtained from gut of O.

niloticus, at concentration of (1×10⁷cfu/g)  (Haematoxylin, eosin)

(X 1000)                                                                                                          143

4.3:      Microvilli, mucosa, muscularis, goblet cell and epithelium layer of H.

longifilis digestive tract after seven months of feeding with artificial feed

pellets coated with Bacillus species obtained from gut of O. niloticus,

at concentration of (5×10⁸cfu/g) (Haematoxylin, eosin) (X 1000)                 144

4.4:      Microvilli, mucosa, muscularis, goblet cell and epithelium layer of H.

            longifilis digestive tract after seven months of feeding with artificial feed

            pellets coated with Bacillus species obtained from gut of O. niloticus,

            at concentration of (1×10⁹cfu/g) (Haematoxylin, eosin) (X 1000)                 145

4.5:      Microvilli, mucosa, muscularis, goblet cell and epithelium layer of H.

            longifilis digestive tract after seven months of feeding with artificial feed

            pellets coated with Pseudomonas species obtained from gut of O.

            niloticus at concentration of (1×10⁷ cfu/g) (Haematoxylin, eosin)

            (X1000)                                                                                                           146

4.6:      Microvilli, mucosa, muscularis, goblet cell and epithelium layer of H.

            longifilis digestive tract after seven months of feeding with artificial feed

            coated with Pseudomonas species obtained from gut of O. niloticus at

            concentration of (5×108cfu/g) (Haematoxylin, eosin) (X1000)                     147

4.7:      Microvilli, mucosa, muscularis, goblet cell and epithelium layer of H.

            longifilis digestive tract after seven months feeding with artificial feed

            coated with Pseudomonas species obtained from gut of O. niloticus at

            concentration of 1×10⁹cfu/g) (Haematoxylin, eosin)  (X 1000)                     148

4.8:      Microvilli, mucosa, muscularis, goblet cell and epithelium layer of H.

            longifilis digestive tract after seven months of feeding with artificial feed

            pellets (control diet). (Haematoxylin, eosin) (X 1000)                                   149

4.9:      Microvilli, mucosa, muscularis, goblet cell and epithelium layer of H.

            ongifilis digestive tract after seven months of feeding with artificial feed

            pellets coated with Candida species obtained from gut of O. niloticus

            at concentration of (1×10⁷cfu/g). (Haematoxylin, eosin) (X 1000)                150

4.10:    Microvilli, mucosa, muscularis, goblet cell and epithelium layer of H.

            longifilis digestive tract after seven months of feeding with artificial

            feed pellets coated with Candida species obtained from gut of O.

            niloticus at concentration of (5×10⁸cfu/g) (Haematoxylin, eosin)

            (X 1000)                                                                                                          151

4.11:    Microvilli, mucosa, muscularis, goblet cell and epithelium layer of H.

            longifilis digestive tract after seven months of feeding with artificial feed

            pellets coated with Candida species obtained from gut of O. niloticus

            at concentration of (1×10⁹cfu/g) (Haematoxylin, eosin) (X 1000)                 152