UNIVERSITI PUTRA MALAYSIA

EVALUATION OF FISH SILAGE AS A PROTEIN SOURCE IN THE DIET FOR RIVER CATFISH

MYSTUS NEMURUS (C. &V.)

BUSTARI HASAN

IB 2001 8

EV ALUA TION OF FISH SILAGE AS A PROTEIN SOURCE IN THE DIET FOR RIVER CATFISH

MYSTUS NEMURUS (C. &V.)

By

BUSTARI HASAN

A Thesis Submitted in Fulfilment of the Requirement for the Degree of Doctor of Philosophy in the Institute of Bioscience

Universiti Putra Malaysia

May 2001

DEDICATION

To my parents, H. Hasan and Hj. Nurimah; my wife Fahria Hadari; my children, Rizka Habiba Bustari and Muhamad Rizki Bustari who gave me

supports and understandings during my study

ii

Abstract of the thesis presented to the Senate of Universiti Putra Malaysia in fulfilment of the requirement for the degree of Doctor of Philosophy

EV ALUATION OF FISH SILAGE AS A PROTEIN SOURCE IN THE DIETS FOR RIVER CATFISH

MYSTUS NEMURUS (C. &V.)

By

BUSTARI HASAN

May 2001

Chairman: Che Roos Saad, Ph.D

Faculty : Institute of Bioscience

A series of experiments was conducted to determine: 1) optimal dietary

energy and protein levels for maximum growth of Mystus nemurus (C. & V.), 2)

preparation and nutritional quality of fish silage, 3) optimal inclusion levels of

fish silage replacing fishmeal in the fish diets, 4) digestibility values of dietary

fish silage by fish. Eight experimental diets were formulated to contain four

energy levels (2.75, 3.00, 3.25 and 3.50 kcal DE/g) at each of the two protein

levels (38% and 42%), and fed to groups of fingerlings (1.88-213 g) for 10

weeks). It was found that the diet containing 3.25 kcal DE/g and 42% protein

(7.74 kcal DElg protein) produced the best growth and food utilization.

Five fermented silage and one acid silage were made from short-bodied

mackerel (Rastrelinger brachysoma). The fermented silage were prepared by the

iii

addition of molasses with different fermentation starters to fish mince, namely:

LBPN (80% fish + 15% molasses + 5% Lactobacillus pentosus pure culture),

LBPL (80% fish + 15% molasses + 5% Lactobacillus plantarum pure culture),

LFBS (70% fish + 15% molasses + 15% liquid fermented bamboo shot), ALPN

(70% fish + 15% molasses + 15% aged Lactobacillus pentosus silage), ALPL

(70% fish + 15% molasses + 15% aged Lactobacillus plantarum silage). Acid

silage (FAS) was made by addition of 3% (w/w) of formic acid to fish mince.

These silage were stored at room temperature for 60-180 days. All silage were

stable in pH « 4.5), and no spoilage odor was detected through out the storage

duration. Nutritional quality of the silage varied with preparation methods.

Fermented silage, especially LBPN was more desirable due to less non-protein

nitrogen production than acid silage.

Fermented and acid fish silage were co-dried with soybean meal (1:1 dry

weight basis) and the mixtures were incorporated in fish diets at various levels

to substitute fishmeal. Eight test diets (42% protein and 4.20 kcal GE/g) were

formulated to contain co-dried fermented fish silage (CFS) and co-dried acid fish

silage (CAS) as a replacement for fishmeal. Four of the test diets were composed

of CFS at the inclusion levels of 15% (CFS-l ), 30% (CFS-2), 45% (CFS-3), and

60% (CFS-4); and the other four diets were composed of CAS at the inclusion

levels of 15% (CAS-I), 30% (CAS-2), 45% (CAS-3), and 60% (CAS-4). A

control diet (C) was prepared with 60% fishmeal without fish silage. The diets

were fed to Mystus nemurus fingerlings for 10 weeks. One percent of chromium

iv

PERPUST'�I.KAAN

lJNIVERSITI PUT�A MALAYSIA

oxide (Cr203) was included in the diets for diet digestibility detennination. The

losses of dry matter (LDM) of the diets after lO and 30 minutes in the water

(LDM-lO min and LDM-30 min) were 2.31-4.47% and 8 . 19- 1 8.58%,

respectively for CFS diets, 2.40-4.5 1 % and 9.32-1 8.26%, respectively for CAS

diets and 2. 12 and 6.43%, respectively for control diet. The pH values were

6.57-5.78 for CFS diets, 5.64-4.96 for CAS diets and 6.78 for control diet. The

essential amino acid profi les (AlE ratio) of both CFS and CAS diets were

comparable to AlE ratio of Mystus nemurus. Apparent dry matter, protein and

energy digestibility values for both CFS and CAS diets were similar to the

control diet. Inclusion of CFS in fish diets up to 45% did not affect growth

perfonnance as compared to control diet. However inclusion of more than 15%

CAS in fish diets reduced growth perfonnance.

v

Abstrak disertasi dikemukakan kepada Senat Universiti Putra Malaysia sebagai me menu hi syarat untuk mendapatkan Ijazah Doktor Falsafah

PENILAIAN SILAJ IKAN SEBAGAI SUMBER PROTEIN DALAM MAKANAN UNTUK IKAN BAUNG

MYSTUS NEMURUS (C&V)

Oleh

BUSTARI HASAN

Mei2001

Pengerusi: Che Roos Saad, Ph.D.

Fakulti : Institut Biosains

Satu siri penyelidikan telah dijalankan untuk mengetahui : 1) paras tenaga

dan protein untuk pertumbuhan maksimum ikan baung (Mystus nemurus,

c.&v.), 2) penyediaan dan mutu pemakanan silaj ikan, 3) paras kandungan silaj

menggantikan tepung ikan dalam makanan ikan dan 4) nilai penghadaman silaj

bagi ikan. Lapan diet ujian dirumuskan mengandungi empat paras tenaga (2.75,

3.00, 3.25 dan 3.50 kcal DE/g) pada setiap paras dari pada dua paras protein (38

dan 42%) dan diberikan kepada kumpulan anak ikan ( 1.88-2. 13 g) selama 10

minggu. Didapati makanan yang mengandung 3.25 kcal DE/g dan 42% protein

(7.74 kcal DE/g protein) menghasilkan pertumbuhan dan penggunaan makanan

yang terbaik.

Lima silaj penapaian dan satu silaj asid dibuat dari ikan kembong kecil

(Rastrelinger branchysoma). Silaj penapaian disediakan dengan penambahan

vi

gula molas dengan starter penapaian yang berlainan kepada hancuran ikan:

LBPN (80% ikan + 15% gula mol as + 5% kultur mumi Lactobacillus pentosus),

LBPL (80% ikqn + 15% gula molas + 5% kultur mumi Lactobacillus

pLantarum), LFBS (70% ikan + 15% gula molas + 15% air jeruk rebung), ALPN

( 70% ikan + 15% gula molas + 15% silaj Lactobacillus pentosus yang sudah

jadi), ALPL (70% ikan + 15% gula molas + 15% silaj Lactobacillus pLantarum

yang sudah jadi). Silaj asid (FAS) dibuat dengan menambahkan asid fonnik 3%

(beratlberat) kepada hancuran ikan. Keseluruhan silaj disimpan pada suhu bilik

selama 60- 180 hari. Keseluruhan silaj adalah stabil dalam pH dan tidak didapati

bau busuk selama penyimpanan. Nilai mutu pemakanan silaj berbeza mengikut

kaedah penyediaan. Silaj peragian, khususnya LBPN lebih dipilih kerana

pengeluaran non-protein nitrogen yang lebih rendah dari pada silaj asid.

Silaj peragian dan silaj asid dikeringkan dengan tepung soya ( 1: 1 berat

kering) dan campuran dimasukan ke dalam makanan ikan pada pelbagai paras

untuk menggantikan tepung ikan. Lapan diet ujian (42% protein dan 4.20 kcal

GE/g) dirumuskan untuk mengandungi silaj penapaian campuran (CFS) dan silaj

asid campuran (CAS). Empat dari pada diet ujian mengandungi CFS: 15% (CFS-

1), 30% (CFS-2), 45% (CFS-3), dan 60% (CFS-4); dan empat diet lain

mengandungi CAS: 15% (CAS-I), 30% (CAS-2), 45% (CAS-3), dan 60%

(CAS-4). Diet kawalan (C) disediakan dengan 60% tepung ikan tanpa silaj.

Kesemua diet diberikan kepada ikan selama 10 minggu. Satu peratus oksida

kromium (Cr203) dimasukan ke dalam diet ikan untuk menentukan nilai

vii

penghadaman diet. Kehilangan bahan kering di dalam air setelah 10 dan 30 minit

(LDM-lO min and LDM-30 min) adalah 2.31-4.47% and 8.19-18.58% berturut­

turut untuk diet CFS, 2.40-4.51 % dan 9.32-18.26% berturut-turut untuk diet

CAS dan 2.12 and 6.43% berturut-turut untuk diet kawalan. Nilai pH adalah

6.57-5.78 untuk diet CFS, 5.64-4.96 untuk diet CAS and 6.78 untuk diet

kawalan. Profil asid amino perlu (AlE ratio) dari kedua diet CFS dan CAS

adalah setara dengan AlE ratio bagi Mystus nemurus. Nilai penghadaman bahan

kering, protein dan tenaga untuk kedua jenis diet adalah serupa dengan diet

kawalan. Pemasukan CFS ke dalam diet sehingga 45% tidak memberi kesan

negatif terhadap pertumbuhan ikan bila dibandingkan dengan diet kawalan.

Namun pemasukan CAS dalam diet melebihi dari 15% akan mengurangi

penampilan pertumbuhan ikan.

viii

ACKNOWLEGEMENTS

The author wishes to express his grateful acknowledgment to Dr. Che

Roos Bin Saad, chairman of his advisory committee, for his assistance, guidance

and friendliness. Sincere gratitude is expressed to Dr. Zaiton Hassan, Associate

Professor Dr. Mohd. Salleh Kamarudin, and Associate Professor Dr. Abdul

Razak Alimon for suggestions and comments. Appreciations are extended to

University Putra Malaysian (IRPA project) and Riau State Government for

financial support during my study. Special thanks are also extended to Institute

of Bioscience, Faculty of Food Science and Biotechnology and Faculty of

Agriculture for Laboratory facilities.

ix

I certifY that an Examination Committee met on 4th May 2001 to conduct the final examination of Bustari Hasan on his Doctor of Philosophy thesis entitled "Evaluation of Fish Silage as a Protein Source in the Diet for River Catfish, Mystus nemurus (C.&V.)" in accordance with Universiti Pertanian Malaysia (Higher Degree) Act 1980 and Universiti Pertanian Malaysia

(Higher Degree) Regulatios 1981. The Committee recommends that the candidate be awarded the relevant degree. Members of the Examination Committee are as follows:

Dahlan Ismail, Ph. D. Professor Department of Animal Science Faculty of Agriculture Universiti Putra Malaysia (Chairman)

Che Roos Saad, Ph. D. Lecturer Institute of Bioscience Universiti Putra Malaysia (Member)

Zaiton Hassan, Ph. D. Lecturer Department of Food Science Faculty of Food Science and Biotechnology Universiti Putra Malaysia (Member)

Mohd. Salleh Kamarudin, Ph. D. Associate Professor Department of Agronomy Faculty of Agriculture Universiti Putra Malaysia (Member)

Abdul Razak Alimon, Ph. D. Associate Professor Department of Animal Science Faculty of Agriculture Universiti Putra Malaysia (Member)

Ahyaudin Ali, Ph.D. Professor Universiti Sains Malaysia (Independent Examiner)

Professor Deputy Dean of Graduate School Universiti Putra Malaysia

Date: 1 1 MA Y 'Oa.!f

x

This thesis submitted to the Senate of Universiti Putra Malaysia has been accepted as fulfilment of the requirement for degree of Doctor of Philosophy.

AINI IDERIS. Ph. D. Professor Dean of Graduate School Universiti Putra Malaysia

Date: .. 1 It JU� i��1

xi

DECLARATION

I hereby declare that the thesis is based on my original work except for quotations and citations, which have been duly acknowledged. I also declare that it has not been previously or currently submitted for any other degree at UPM or

other institutions

BUSTARI HASAN

Date: 'Vs-/ t:2IrD/

xii

TABLE OF CONTENTS

Page

DEDICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii ABSTRAK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VI

ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix APPROV AL SHEETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x DECLARATION FORM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii LIST OF TABLES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii LIST OF PLATES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviii LIST OF ABBREVIATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix

CHAPTER

GENERAL INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 LITERATURE REVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Importanc e of Energy-protein Ratio in Fish Di ets . . . . . . . . . . 6 Preparation and Nutritional Quality of Fish Silage. . . . . . . . . . . 1 3 Use of Fish Silage in Di ets for Animal and Fish . . . . . . . . . . . . 23 Digestibility Determinations and their V alues for Various

Feedstuffs by Fish. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

3 GENERAL METHODOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . 36 Exp erimental Faciliti es . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Experimental Diets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Experimental Animals and Feeding Trials. . . . . . . . . . . . . . . . . . 40 Analytical and Statistical Proc edures . . . . . . . . . . . . . . . . . . . . . 42

4 OPTIMUM DIETARY ENERGY AND PROTEIN LEVELS FOR MAXIMUM GROWTH OF MYSTUS NEMURUS . . . . . 49 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Materi als and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

xiii

5 PREPARATION AND EVALUATION OF FISH Sfi.,AGE . . . 72 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . ..... . . . 73 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Discussion . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Conclusion . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

6 EFFECTS OF SUBSTITUTION OF FISHMEAL WITH CO-DRIED FISH Sfi.,AGE ON GROWTH PERFORMANCE OFMYSTUS NEMURUS . .. .. .. .. .. . . . ... ............ 88 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 Materials and Methods . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 Results . . . . . , . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . 93 Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

7 DIGESTffifi.,ITY OF CO-DRIED FISH Sfi.,AGE IN MYSTUSNEMURUS . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 115 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 Discussion .. . . . . ................................... 124 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

8 GENERAL DISCUSSION ...... . . . ... . . . . . . . . . . . . . . .. . 127

9 GENERAL CONCLUSION. . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

BffiLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . 134 APPE1\'1)ICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 BIODATA OF THEAUTHOR . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 162

xiv

LIST OF TABLES

Table Page

4.1 Proximate Composition of Feed Ingredients Used for Energy-protein Experimental Diets .. . . . . . . . . . . . . . . . . . . " 52

4. 2 Formulation and Proximate Composition of Energy-protein Experimental Diets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

4.3 Means of Water Quality Parameters Measured During Feeding Trials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

4.4 The Effects of Dietary Energy and Protein Levels on Daily Intake of Food (FI), Protein (PI) and Energy (EI) . . . . . . . . . . . 55

4.5 The Effects of Dietary Energy and Protein Levels on Weight Gains (WG), Protein Gains (PG), and Fat Gains (FG) . . . . . . . . 59

4.6 The Effects of Dietary Energy and Protein Levels on Food Efficiency Ratio (FER), Protein Efficiency Ratio (PER) and Net Protein Utilization (NPU) . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

4. 7 The Effects of Dietary Energy and protein Levels on Fish Body Composition . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

5.1 Changes in pH, Titratable Acidity (TA), Lactic Acid Bacterial (LAB) Count and Non-protein Nitrogen (NPN) Values of Fish Silage During Storage Periods. . . . . . . . . . . . . . . . . . . . . . . . . .. 78

5. 2 Proximate Composition of Fish Silage During Storage Periods.. . . . . . . . . . . . . .. . . . ........................ ........ 80

5.3 Amino Acid (AA) Composition (% Protein) of Raw fish (RF) and 30 Day Stored Fish Silage . . . . . . . . . . . . . .. . . . . . . . . . . . . 82

6.1 Formulation of the Experimental Diets. . . . . . . . . . . . . . . . . . . . 91

6. 2 Chemical and Energy Composition of Feed Ingredients for Experimental Diets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 94

xv

6.3 Essential Amino Acid (EAA) Composition (% Protein) of Co-dried Fermented Fish Silage (CFS), Co-dried Acid Fish Silage (CAS) and Fishmeal (FM) (Means of Triplicate Samples) ................. ... . ........... . . ... .... .. . 95

6.4 Determined Chemical and Energy Composition of Control (C) and Co-dried Fermented Fish Silage (CFS) Diets. . . . . . . . . . .. 96

6.5 Determined Chemical and Energy Composition of Control (C) and Co-dried Acid Fish Silage (CAS) Diets. . . . . . . . . . . . . . . .. 97

6.6 Essential Amino Acid (EAA) Composition (% Protein) of Control (C) and Co-dried Fermented Fish Silage (CFS) Experimental Diets (Means of Triplicate Samples) . . . . . . . . . . . 99

6.7 Essential Amino Acid (EAA) Composition (% Protein) of Control (C) and Co-dried Acid Fish Silage (CAS) Experimental Diets (Means of Triplicate Samples) . . . . . . . . . .. 100

6.8 AlE Ratio (percentage of Essential Amino Acidlfotal Essential Amino Acid) of Control (C), Co-dried Fermented Fish Silage (CFS) Diets and Mystus nemurus (Means of Triplicate Samples). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 101

6.9 AlE Ratio (Percentage of Essential Amino Acidlfotal Essential Amino Acid) of Control (C), Co-dried Acid Fish Silage (CAS) Diets and Mystus nemurus. (Means of Triplicate Samples) .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 102

6.10 Water Stability (%Loss Dry Matter, LDM) and pH Values for Control (C), Co-dried Fennented (CFS) and Acid Fish Silage (CAS) Pellet Feeds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

6.11 Growth Perfonnance and Food Utilization of Fish Fed Control (C) and Co-dried Fennented Fish Silage (CFS) Diets. . 106

6.12 Growth Perfonnance and Food Utilization of Fish Fed Control (C) and Co-dried Acid Fish Silage (CAS) Diets 107

6.13 Body Composition of Harvested Fish Fed Control (C) and Co-dried Fermented Fish Silage (CFS) Diets . ... .. ..... . . . . 108

6.14 Body Composition of Harvested Fish Fed Control (C) and Co-dried Acid Fish Silage (CAS) Diets.. . . . . . . . . . . . . . . . . . .. 108

XVI

7. 1 Formulation, Chemical and Energy Composition of Reference (REF) and Test Diets for Digestibility Determination of Individual Silage Ingredients ............................ 1 18

7.2 Composition of Reference (REF) and Test Diets for Digestibility Determination of Complete-Silage Diets ........ 1 19

7.3 Apparent Digestibility Coefficients for Dry Matter, Protein and Energy in Reference (REF) and Test ingredients (70% Reference Diet + 30% Ingredient) ........................ 12 1

7.4 Dry Matter, Crude Protein and Energy Digestibility Coefficients Estimated for Co-dried Fermented Fish Silage (CFS), Acid Fish Silage (CAS), and Fishmeal (FM) Ingredients .............. 122

7.5 The Effects of Co-dried Fermented Fish Silage (CFS) Levels on Protein and Energy Digestibility of the Diets ............... 123

7.6 The Effects of Co-dried Acid Fish Silage (CAS) Levels on Protein and Energy Digestibility of the Diets ............... 124

xvii

LIST OF FIGURES

Figures

4.1 Regression of Daily Intake of Food (A), Protein (B) and Energy (C) On Dietary Energy Levels at Two Different Protein

Page

Concentrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 56

4.2 Biweekly Mean Fish Size (FS) and Daily Intake of Food (PI) and Protein (PI) (A) and Energy (EI) (B) .. . . .. . ... . . . . . . .. 58

4.3 Regression of Gains in Weight (A), Protein (B) and Fat (C) on Dietary Energy Levels at Two Different Protein Concentrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 60

4.4 Regression of FER (A), PER (B) and NPU (C) on Dietary Energy Levels at Two Protein Different Concentrations . . . . . . 63

xviii

LIST OF PLATES

Plates

3.1 Experimental Tanks for Dietary Energy-protein Ratio

Page

Feeding Trials . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. 37

3.2 Experimental Tanks for Dietary Fish Silage Feeding Trials ... . 37

3.3 Experimental Tanks for Diet Digestibility Determination . . . . . . 38

5.1 Selection of Lactic Acid Bacteria by pH Levels .. . . . . . . . . . .. 75

5.2 Identification of Lactic Acid Bacteria Using API 50 CHL Medium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 76

xix

LIST OF ABBREVIATIONS

AA= Amino acid

ADC= Apparent digestibility coefficient

ME ratio= Amino acid/total essential amino acid (%)

ALPN= Aged-silage Lactobacillus pentosus

ALPL= Aged-silage Lactobacillus plantarum

ANOV A= Analysis of variance

AOAC= Association of official analytical chemists

BHT= Butylated hydroxy toluene

C= Control

CFS= Co-dried fermented Fish silage

CAS=Co-dried acid Fish silage

CP= Crude protein

DE=: Digestible energy

DHA= Decosahexaenoic acid

EAA= Essential amino acid

EI= Energy intake

EPA- Eicosapentaenoic acid

FAS= Formic acid silage

FER= Food efficiency ratio

FG= Fat gain

FI= Food intake

xx

PM= Fishmeal

FS= Fish size

GE= Gross energy

HPLC= High performance liquid chromatography

IDF= International dairy federation

Kcal= Kilo calorie

LAB= Lactic acid bacterial counts

LBPN= Lactobacillus pentosus

LBPL= Lactobacillus plantarum

LDM= Loss of dry matter (%)

LFBS= Liquid fermented bamboo shoot silage

ME= Metabolisable energy

Min. mix= Mineral mixture

MRS= De Man Rogosa Sharpe

NPN= Non-protein nitrogen

NPU= Net protein utilization

NRC= National research council

PE= Protein-energy

PER= Protein efficiency ratio

PG= Protein gain

PI= Protein intake

PKC= Palm kernel cake

PO= Palm oil

xxi

REF= Reference

RF= Raw fish

SAS= Statistical analysis system

SBM= Soybean meal

SD=Standard deviation

SEM= Standard error of means

SGR= Specific growth rate

SR= Survival rate

TA= Titratable acidity

TeA= Trichloroacetic acid

Vit. mix= Vitamin mixture

WG= Weight gain

xxii

CHAPTER!

GENERAL INTRODUCTION

Aquaculture in Malaysia has rapidly expanded recently. Since 1990, the

total area devoted has increased from 9,085.03 to 16 , 1 66.93 hectares in 1998;

and aquaculture production increased from 14,788.77 tons in 1 990 to 133,646.64

tons in 1998, with values reaching RM 654,294.77 millions in 1 998 (Anon,

1 990- I 998).

One of the popular and highly demanded aquaculture species is the river

catfish (Mystus nemurus). Naturally, the fish is a carnivorous species with stout,

sturdy and scaleless body of 0.4- 1 .5 kg in weight, and of lake or river origin and

bottom feeder (Khan, 1 993). The fish is identified as a potential aquaculture

species due to its successful artificial spawning, ability to withstand in relatively

low pH and dissolved oxygen, high dress-out percentage as well as high

economic value (Khan et aI., 1 993a and Khan, 1 993).

Extensive culture of the species has been practiced in cages and

reservoirs. Seed supply is routinely available from Freshwater Research Center

in Malacca, Aquatic Resources Technology at Universiti Putra Malaysia and

other private hatcheries around Peninsular Malaysia. The fish is cultured at a

density rate of 2000 fish per hectare and fed with commercial fish pellets, trash