GREEN ALGAE AS PROTEIN SOURCE FOR OREOCHROMIS

274 Pages·2012·9.04 MB·English

GREEN ALGAE AS PROTEIN SOURCE FOR
OREOCHROMIS NILOTICUS AND TILAPIA ZILLII
by
HENRY NORTEY APPLER N\5c.
Thesis submitted to the University of Stirling
for the Doctor of Philosophy
Institute of Aquaculture
Stirling University
Stirling
SCOTLAND
December 1982
CONTENTS Page No.
Acknowledgements
Abstract
•
1 General Introduction 1
1.1 Preface 1
1.2 General uses of algae 2
1.2.1 Algal culture as a waste
water treatment process 3
1.2.2 The use of algae as fertilizers 4
1.2.3 The use of algae as source of
chemicals 5
1.2.4 The use of algae as feedstuff 6
1.3 The potential of algae as an animal
feedstuff 10
1.4 Status of algae as food for fish and
shell fish 15
1.5 A brief review of the experimental
algae and fishes employed 18
1.5.1 Algae 18
1.5.2 Fishes 22
1.6 Aims of the research 24
2 General Materials and Methods 28
2.1 £xperimental facilities 28
2.1.1 "System 1" Static water tanks 31
2.1.2 "System 2" Recirculation s9stem 32
2.2 Diet formulation 34
2.3 Diet preparation 37
2.4 Acclimatization and weighing procedure 38
2.5 Methods of proximate analysis 38
2.6 Histological studies 40
2.7 Enzyme studies 40
Page No.
2.8 Analysis of experimental data 41
2.9 Digestibility determination 43
3 Culturing of the microalgae ChIarella vulgaris
and Scen'edesmus oblig uus 45
3.1 Introduction 45
3.2 Material and Methods 46
3.2.1 Algal culture unit 46
3.2.2 Culturing of algae 50
3.2.3 Growth characteristics of algae 51
3.2.4 Harvesting of algae 51
3.2.5 Chemical analysis of algae 52
3.3 Results 52
3.3.1 Growth and yield of algal
cultures 52
3.3.2 Chemical composition 56
3.4 Discussion and conclusion 60
4 The evaluation of ChIarella vulgar~s as
a protein source for Oreochromis niloticus
and Tilap1a zillii. 64
Introduction 64
Experiment I (The utilization of
varying cell concentrations of
fresh Q. vulgaris. 67
4.2.1 Materials and methods 67
4.2.2 Results 69
4.3 Experiment II (The effect of various
algal treatments on Chiorelia vulgaris
utilization 7a
4.3.1 Materials and methods 79
4.3.2 Results 83
Page No.
4.4 Experiment III (Determination of
the optimum time for boiling the
alga) • 97
4.4.1 Introduction 97
4.4.2 Results 97
4.5 Discussion and conclusions 106
5 The evaluation of Scenedesmus ohliguus
as a protein source for Oreochromis niloticus
and Tilapia zillii. 118
5.1 Introduction 118
5.2 Experiment I (The effect of varying
s.
concentrations of obliguus on the
growth, food conversion and protein
utilization of niloticus and
~.
1. zillii. 119
5.2.1 Materials and methods 119
5.2.2 Results 121
Experiment II (The effect of
s.
pretreatment on ohliguus
utilization) 126
5.3.1 Materials and methods 126
5.3.2 Results 126
Experiment III (Determination of
the optimum time for boiling the alga) 137
5.4.1 Materials and methods 137
5.4.2 Results 139
5.5 Discussion and conclusions 145
6 The progressive substitution of fishmeal
with Cladophora glomerata in pelleted feeds
and its effects on 'growth and protein
utilization of Oreochromis niloticus
and Tilapia zillii. 152
6.1 Introduction 152
6.2 Materials and methods 153
Page No.
6.3 Results 158
6.4 Discussion and conclusions 168
7 The progressive substitution of fishmeal
with Hydrodictyon reticulatum and its
effects on growth, protein utilization
and digestive enzyme activities of
Oreo'chromis niloticus and Ti1apia zi11ii. 173
7.1 Introduction 173
7.2 Materials and methods 175
7.3 Results 179
7.4 Discussion and conclusions 190
8 The effect of amino acid supplementation
on the nutritive value of Hydrodictyon
reticula,tum. 197
8.1 Introduction 197
8.2 Materials and Methods 199
8.3 Results 204
8.4 Discussion and conclusions 216
9 General Conclusions 222
References 226
Appendices
ACKNOWLEDGEMENTS
This study was undertaken as part of the Overseas
Development Aid Programme for Developing Countries. I am
very grateful the ODA for sponsoring my study. My thanks
t~
are extended to Mr J. Stoneman of the ODA for his encourage
ments during his regular visits the Institute of
t~
Aquaculture.
I am very much indebted to my supervisors, Professor
R.J. Roberts and Dr Kim Jauncey for their excellent super
vision and guidance throughout the study. Many thanks are
due to Dr J.F. Muir who helped in many ways to get the
project started. To other members of staff who helped in
various ways to get this study completed, I say thank you.
Thanks are also due to the technical staff and members of
K3, particularly Mr Jeremy Langdon, who assisted me during
the course.
Finally, I would like to thank Mrs Lyn North for
drawing the figures and Miss Sheena Wales for typing the
thesis.
This thesis is devoted to the memory of my late
father, James Appler de Nortey.
ABSTRACT
The potential of the unicellular green algae ChI orella
vulgaris and Scenedesmus obliguus and the filamentous green
algae Cladophora glomerata and Hydrodictyon reticulatum
as protein sources in Oreochromis niloticus and Tilapia
zillii diets was investigated.
When Q. niloticus and !. zillii were fed with fresh
£.
C. vulgaris and obliguus, a high percentage of the
ingested algae was found to be undigested. Heat treatment
of the algae at 40°, 60°, 80° and 100°C produced increased
growth and protein utilizations in the fishes compared to
those fed the untreated algae. Feeding Q. vulgaris treated
at 1000C for 30 minutes and S. obliguus treated at 1000C
for 15 minutes was found to have produced the best growth
responses in.Q. niloticus and!. zillii.
E.
Q. glomerata meal and reticulatum meal were each
fed separately as fishmeal substitutes in pelleted rations
formulated to contain 30% protein with varying proportions
of this supplied by the fishmeal and the algal meal. A
diet containing 25% protein supplied by the algal meal
alone was also fed. When 5% of the fishmeal protein was
replaced with algal protein (both Q. glomerata and lie
reticulatum) and fed to !. zillii, the growth and protein
utilization values recorded were superior to those 'obtained
for the control 30% fishmeal protein diet. Higher levels
of algal protein substitution were, however, found to
produce poorer growth and protein utilization values in
both fish species. Diets containing only algal protein
(both Q. glomerata and H. reticulatum) produced the poorest
growth responses in both fish species.
Hydrodictyon reticulatum was found to be limiting in
methionine and histidine. Supplementation of these
essential amino acids produced improved growth in both
Q. niloticus and T. zillii.
It was concluded from these studies that the green
algae evaluated may be suitable partial dietary protein
sources for tilapias.
CHAPTER 1. GENERAL INTRODUCTION
Section 1.1 Preface,
The worldwide shortage of edible protein requires
no emphasis (FAO, 1963; Enebo, 1968). In the search
for new sources of readily available protein, alg'ae are
attracting the attention of nutritionists and technologists
as one possibility for helping to solve the world protein
shortage, particularly in developing countries. The
role of algae as a possible novel protein source is under
investigation to evaluate its technological feasibility,
economics of production and" its suitability for year
round cultivation in tropical and sub-tropical countries
(Dabah, 1970; Waslien, 1975).
Algae have been used, probably since prehistoric
times, as a direct source of protein and vitamins by man.
The present utilization of algae, particularly microalgae,
has originated from three roots: ancient traditions,
scientific-technological developments of algal culture
and the 'green trend' in sanitary engineering (Soeder,
1980a).
An important discovery of the Belgian Sahara
Expedition of 1964 - 65 was that, the blue-green alga
Spirulina, which forms dense blooms in brackish warm
waters, was regularly collected and consumed by the native
people around Lake Chad in Central Africa (Leonhard et
Compere, 1967). In his report on microalgae that are
2
eaten directly by man, Johnston (1970) not only described
the discovery of Spirulina as a human dietary component
but also stated that other blue-green algae such as
Nostoc pruniforme, Nostoc commune, Nostoc verrucosum and
Phylloderma sacrum have been marketed and eaten in Japan,
China, Mongolia and Peru. Species of green algae particu
larly, Spirogyra, Oedogonium and Prasiola, are also eaten
in Japan, India, Thailand and Burma.
A scientific approach to the mass culture and
utilization of algae, however, began with the introduction
of dense suspensions of ChI orella as a tool for research
into photosynthesis by Warburg (1919). It has beerr
subsequently recognised that certain microalgae can
increase their biomass many times (up to? lOOx) per day
under suitable laboratory conditions and that their dry
matter may contain more than 50% of crude protein. This
realisation has led to the expansion of applied micro
algae research. The practical results of such mass culture
studies on algae have led to fue development of various
uses for algae.
Section 1.2 General uses of algae
The present extensive uses of algae range from
waste water treatment to their use as sourcesof chemicals
and as feedstuffs.