Tiến Sĩ Evaluation of Local Feed Resources for Hybrid Catfish (Clarias macrocephalus x C. gariepinus) in Sma

LUẬN ÁN TIẾN SĨ
Doctoral Thesis Swedish University of Agricultural Sciences Uppsala 2010


Contents
List of Publications 9
Abbreviations 10
1 Introduction 11
2 Background 13
2.1 The role of fresh water aquaculture in food supply and rural
development in Vietnam 13
2.2 Development of fresh water aquaculture in Vietnam 14
2.3 Fish species used in smallholder fish farming 15
2.4 Current status and constraints of feed and feeding for inland
aquaculture in Vietnam 17
2.5 Amino acid requirements in fish 18
2.5.1 Qualitative amino acid requirements 18
2.5.2 Lysine requirement 18
2.5.3 A/E ratios and the ideal protein concept 18
2.6 Alternative protein sources for fish 20
2.6.1 Terrestrial plant-based proteins 20
2.6.2 Rendered terrestrial animal products 21
2.6.3 Seafood by-products 21
2.7 Digestibility in fish 22
2.7.1 Nutrient digestion 22
2.7.2 Determination of digestibility 23
2.7.3 Factors influencing digestibility 24
3 Materials and Methods 27
3.1 The survey 27
3.1.1 Site and household selection 27
3.1.2 Interviews 27
3.1.3 Sample collection 28
3.1.4 Chemical analysis 28
3.1.5 Statistical analysis 28
3.2 Fish experiments 28
3.2.1 Location 28
3.2.2 Experimental design 28
3.2.3 Experimental fish and facilities 29
3.2.4 Fish management 29
3.2.5 Feed ingredients and diet formulation 30
3.2.6 Sample collection, measurements and calculations 31
3.2.7 Chemical analysis 32
3.2.8 Statistical analysis 32
4 Summary of results 33
4.1 Potential feed resources and diet formulation at farm level
(Paper I) 33
4.2 Fish yield (Paper I) 34
4.3 Digestibility of nutrients and amino acids of selected feedstuffs
in hybrid catfish and Nile tilapia (Paper II) 34
4.4 Essential amino acids requirements of hybrid catfish (Paper III) 35
4.5 Growth performance of hybrid catfish fingerlings fed diets with
partial replacement of fish meal by cassava leaf meal or shrimp
head meal, without or with lysine supplementation (Paper IV) 36
5 General discussion 37
5.1 Potential feed resources for fresh water fish in Central Vietnam 37
5.1.1 Energy feeds 37
5.1.2 Protein-rich feedstuffs 38
5.2 Apparent digestibility of nutrients in hybrid catfish and Nile tilapia 40
5.3 Dietary essential amino acids requirements 41
5.4 Replacing fish meal by local protein-rich feed sources 42
6 General conclusions and implications 45
6.1 Conclusions 45
6.2 Implication and further study 46
6.2.1 Implication 46
6.2.2 Further study 46
References 47
Acknowledgements 57

1 Introduction
Worldwide, aquaculture is developing, expanding, and intensifying. In
Southeast Asia, aquaculture output has been increasing rapidly, especially
during the last 15 years. Recently, the production from capture fisheries
has leveled off, and most of the main fishing areas have reached their
maximum potential, and therefore, in order to meet the growing global
demand for aquatic food, aquaculture appears to have the potential to make
a significant contribution to this increasing demand (FAO, 2006).
Vietnam is a tropical country with a high rainfall and with around 1.7
million hectares of inland water suitable for aquaculture development.
Production of fresh water aquaculture has been rapidly increasing in recent
years, reaching around 1.86 million tonnes in 2008, contributing to about
75 % of the total aquaculture production (GSO, 2010). The growth rate of
fresh water aquaculture production was 8 % per year in the period 1985-
1998 and the plan of the Government is to achieve two million tonnes by
2010. This growth of fresh water aquaculture production is mainly
expected to come from small-scale aquaculture (Hung, 2004; Tung, 2000).
However, in order to achieve this target, the sector will face significant
challenges (FAO, 2006). Among these, the quantity and quality of feed is a
major constraint. Feed is the principle cost in the cultivation of most fish
species and this cost has tended to increase with the rising price of fish
meal. The feed cost had increased by 73 % in 2008 compared with the
price in 2005 (Hishamunda et al., 2009; Rana et al., 2009; Edwards et al.,
2004). It was reported that during late 2008, feed prices had increased by
over 30 % on average in many Asian countries, while the prices of
aquaculture products had remained the same. This is a challenge for
thousands of small-scale producers that form the backbone of the
aquaculture sector (Rana et al., 2009).
12
In Vietnam, small-scale aquaculture is an important sub-sector in the
rural economy that contributes significantly to the nation’s food security,
family nutrition, economy and employment, especially in the rural areas.
Fish is a traditional food of the Vietnamese people (Tu & Giang, 2002),
and about 30 % of the total animal protein intake of the Vietnamese people
comes from fish. Small-scale aquaculture, which presently contributes over
70 % of the national aquaculture production, is a potential resource for
improving household food security and supplementary family income for
the rural poor (Tung, 2000). Therefore, an improved feeding system
incorporating locally available feed resources for smallholder fish farming
would be very useful for the farmers in Central Vietnam.
Objectives of the study:

To examine and evaluate the current feeding situation for fresh water
fish in Central Vietnam and to provide a database on locally
available feed resources for fish.

To evaluate the potential nutritive value of local feed resources,
readily available in Central Vietnam, as feed ingredients for hybrid
catfish (Clarias macrocephalus x C. gariepinus) and Nile tilapia
(Oreochromis niloticus).

To determine the dietary requirement of lysine for hybrid catfish and
to estimate the requirements for the other essential amino acids
(EAA) by using the ideal protein concept.

To evaluate the suitability of cassava leaf meal and shrimp head meal
as a partial substitute for fish meal in the diet, without or with lysine
supplementation, for hybrid catfish fingerlings.