Tiến Sĩ Evaluation of Locally Available Feed Resources for Striped Catfish (Pangasianodon hypophthalmus)

LUẬN ÁN TIẾN SĨ
NĂM 2012
Doctoral Thesis
Swedish University of Agricultural Sciences
Uppsala 2012


Evaluation of Locally Available Feed Resources for Striped Catfish (Pangasianodon hypophthalmus)
Đánh giá các nguồn thức ăn tại địa phương có sẵn cho Cá da trơn (Pangasianodon hypophthalmus)

Contents
List of Publications 7
Abbreviations 8
1 Introduction 11
2 Objectives of the thesis 13
2.1 The specific aims 13
2.2 Hypotheses examined in the thesis 13
3 Background 15
3.1 The role of striped catfish farming systems in Vietnam 15
3.2 Feed and feeding practices in striped catfish farming 15
3.3 Potential feed protein resources used for aquafeeds 16
3.4 Alternative protein sources to fish meal in aquaculture diets 16
3.4.1 Terrestrial plant-based protein 17
3.4.2 Terrestrial animal by-products 17
3.5 Nutrient requirement of catfish 17
3.5.1 Protein requirements 17
3.5.2 Essential amino acid requirements 18
3.5.3 Lipid requirements 20
3.5.4 Carbohydrate and fibre requirements 20
3.5.5 Energy requirement 21
3.6 Digestibility in fish 21
3.6.1 Methods used in digestibility determination 21
3.6.1.1 Direct method 21
3.6.1.2 Indirect method 22
3.6.2 Factors affecting digestibility 22
3.6.3 Protein and amino acid digestibility 23
3.6.4 Carbohydrate and fibre digestibility 23
3.6.5 Energy digestibility 24
3.6.6 Digestibility of lipids 24
3.7 Anti-nutrients present in feed ingredients 25
3.8 Environmental impact and water quality monitoring 27
3.8.1 Environmental impact assessment of intensive catfish farming 27
3.8.2 Water quality monitoring 27
3.8.3 Phytoplankton and zooplankton monitoring 28
4 Materials and methods 29
4.1 Study site 29
4.2 Field survey and feed samplings (Paper I) 29
4.3 Fish experiments (Papers II, III, IV & V) 30
4.3.1 Experimental design 30
4.3.2 Experimental fish 30
4.3.3 Experimental diets 30
4.3.4 Experimental feed ingredients 33
4.3.5 Feeding and feed preparation 33
4.3.6 Experimental system and management 34
4.3.7 Sample collection and calculations 34
4.3.8 Water quality monitoring 35
4.3.9 Chemical analysis 36
4.3.10 Statistical analysis 36
5 Summary of major results 37
5.1 Chemical composition of feed ingredients 37
5.2 Chemical composition of diets 39
5.3 Feed digestibility 39
5.3.1 Digestibility of diets 39
5.3.2 Digestibility of feed ingredients 43
5.4 Growth performance and feed utilisation 45
5.5 Carcass and body indices (Papers IV & V) 47
5.6 Water quality and plankton monitoring 48
5.6.1 Water quality monitoring 48
5.6.2 Plankton monitoring and assessment 48
6 General discussion 51
6.1 Feed and feeding in small-scale striped catfish farming 51
6.2 Potential feed ingredient resources for striped catfish 51
6.2.1 Plant feed ingredients 52
6.2.2 Animal feed ingredients 52
6.3 Nutrient digestibility of potential local feeds in striped catfish 53
6.4 Replacing fish meal with locally available feed resources 55
7 General conclusions and applications 59
7.1 Conclusions 59
7.2 Implications and further research 60
7.2.1 Implications 60
7.2.2 Future research 60
References 61
Acknowledgements 77

1 Introduction
Diets for most farmed carnivorous and omnivorous fish, marine finfish and
crustaceans are still largely based on fish meal from marine resources,
especially low-value pelagic fish species. Fish meal is the major dietary protein
source for aquafeeds, commonly making up between 20˗60% of fish diets
(FAO, 2012; Glencross et al., 2007; Watanabe, 2002). It has been estimated
that in 2008, the aquaculture sector used 60.8˗71.0% of world fish meal
production (FAO, 2012; Lim et al., 2008; Tacon & Metian, 2008). Dietary
protein is the major and most expensive component of formulated aquafeeds
(Wilson, 2002) and feed costs have tended to increase with the rising price of
fish meal. Thus, the cost of aquafeeds increased by 73% from 2005 to 2008
(FAO, 2012). Therefore, in order to reduce feed costs and the use of fish meal
in aquafeeds, more extensive use of alternative feed ingredients is needed (Burr
et al., 2012; Hardy, 2010; Lim et al., 2008; Glencross et al., 2007).
Freshwater striped catfish (Pangasianodon hypophthalmus) is a Pangasiid
species of high economic value for fish farming in South-East Asia (Hung et
al., 2004). This fish species has become an iconic success story of aquaculture
production in Vietnam and has evolved into a global product (Silva & Phuong,
2011; Phuong & Oanh, 2010). Glencross et al. (2011) reported that
improvement of the nutrition and feed management of the expanding local
striped catfish industry in Vietnam has been identified as a key priority to
improve production efficiency. Although soybean meal has been used in
striped catfish feed as a replacement for fish meal, trash fish (marine origin)
and fish meal are still the main dietary protein sources for striped catfish,
comprising 20˗60% of the feed (Da et al., 2011; Phumee et al., 2009; Hung et
al., 2007). However, using fish meal is not a sustainable long-term feeding
strategy (FAO, 2010; Naylor et al., 2009), and it will lead to the decline of
some trash fish species and even to extinction (Edwards et al., 2004). As the
aquaculture industry is projected to continue expanding, fish meal must be
used more strategically as the required aquafeed production volumes increase
(Güroy et al., 2012). This will be a major challenge for thousands of smallscale
striped catfish producers, as the feed is a major component of the total
production costs and many fish farmers still rely heavily on trash fish and fish
meal (Tacon & Metian, 2008). Increased use of cheap, locally available feed
resources and more sustainable protein sources is considered a high priority in
aquafeed industry and could provide a way to reduce the total production costs
(Hardy, 2010; Edwards & Allan, 2004). Thus, development of feeding systems
based on locally available feed resources for small-scale striped catfish farming
in the Mekong Delta of Vietnam would be a way to improve the profitability of
the industry and make the production more sustainable.