Evaluation of Locally Available Feed Resources for Striped Catfish (Pangasianodon hypophthalmus) Chau Thi Da Faculty of Veterinary Medicine and Animal Science Department of Animal Nutrition and Management Uppsala Doctoral Thesis Swedish University of Agricultural Sciences Uppsala 2012 Acta Universitatis agriculturae Sueciae 2012: 89 Cover: Natural feed resources for striped catfish in the Mekong Delta, Vietnam (photo: Chau Thi Da, 2011) ISSN 1652˗6880 ISBN 978˗91˗576˗7736˗5 © 2012 Chau Thi Da, Uppsala Print: SLU Service/Repro, Uppsala 2012 Evaluation of Locally Available Feed Resources for Striped Catfish (Pangasianodon hypopthalmus) Abstract This thesis investigated and compared inputs and outputs, economic factors and current feed use in small-scale farming systems producing striped catfish (Pangasianodon hypophthalmus) in the Mekong Delta The nutrient content of locally available natural feed resources for striped catfish was determined and growth performance, feed utilisation and body indices were analysed in pond-cultured striped catfish fed diets where fish meal protein was replaced with protein from local feed resources A survey showed that around 15 feed ingredients are used in striped catfish pond culture in the region The combination of feed ingredients used in farm-made feeds varied among fish farms The cost of producing kg of fish using farm-made feeds was usually 8˗10% lower than that of using commercial feeds Digestibility trials on selected potential feedstuffs showed that the apparent digestibility (AD) of DM, CP, OM and energy was highest in soybean meal, groundnut cake, broken rice, shrimp head meal, golden apple snail and catfish by-product meal and earthworm meal, whilst the digestibility was in lower cassava leaf meal and sweet potato leaf meal The average digestibility of most essential amino acids (EAA) in selected feed ingredients was high (range 70˗92%), indicating high protein quality of these feedstuffs In general, the AD of individual EAA was high for all diets except those with cassava leaf meal, rice bran and earthworm meal, where the AD of EAA was reduced Two different growth experiments with the same diet (20˗100% replacement of fish meal) were performed in an indoor and an outdoor culture system A significant finding was that daily weight gain (DWG) was much higher (3.2˗ to 6˗fold) in outdoor culture conditions compared with indoor Feed conversion rate and feed utilisation were also 0.2˗0.7 units (kg feed DM/kg weight gain) higher in the outdoor system The results suggest that fish meal protein in feed for striped catfish fingerlings can be replaced with protein from locally available plant and animal ingredients without compromising growth performance, feed utilisation or carcass traits Keywords: striped catfish, local feed resources, dietary components, amino acids digestibility, alternative protein, growth performance Author’s address: Chau Thi Da, Department of Aquaculture, Faculty of Agriculture and Natural Resources, An Giang University, Vietnam P.O Box: No 18 Ung Van Khiem, Dong Xuyen ward, Long Xuyen city, An Giang province, Vietnam Email: chau.thida@gmail.com and ctda@agu.edu.vn Dedication To my family with my respectful gratitude, My wife Thái Huỳnh Phương Lan, My son Chau Thái Sơn, and My son Chau Thái Bảo Contents List of Publications 7 Abbreviations 8 1 Introduction 11 2 2.1 2.2 Objectives of the thesis The specific aims Hypotheses examined in the thesis 13 13 13 3 3.1 3.2 3.3 3.4 Background The role of striped catfish farming systems in Vietnam Feed and feeding practices in striped catfish farming Potential feed protein resources used for aquafeeds Alternative protein sources to fish meal in aquaculture diets 3.4.1 Terrestrial plant-based protein 3.4.2 Terrestrial animal by-products Nutrient requirement of catfish 3.5.1 Protein requirements 3.5.2 Essential amino acid requirements 3.5.3 Lipid requirements 3.5.4 Carbohydrate and fibre requirements 3.5.5 Energy requirement Digestibility in fish 3.6.1 Methods used in digestibility determination 3.6.1.1 Direct method 3.6.1.2 Indirect method 3.6.2 Factors affecting digestibility 3.6.3 Protein and amino acid digestibility 3.6.4 Carbohydrate and fibre digestibility 3.6.5 Energy digestibility 3.6.6 Digestibility of lipids Anti-nutrients present in feed ingredients Environmental impact and water quality monitoring 3.8.1 Environmental impact assessment of intensive catfish farming 3.8.2 Water quality monitoring 3.8.3 Phytoplankton and zooplankton monitoring 15 15 15 16 16 17 17 17 17 18 20 20 21 21 21 21 22 22 23 23 24 24 25 27 27 27 28 Materials and methods Study site 29 29 3.5 3.6 3.7 3.8 4 4.1 4.2 4.3 Field survey and feed samplings (Paper I) Fish experiments (Papers II, III, IV & V) 4.3.1 Experimental design 4.3.2 Experimental fish 4.3.3 Experimental diets 4.3.4 Experimental feed ingredients 4.3.5 Feeding and feed preparation 4.3.6 Experimental system and management 4.3.7 Sample collection and calculations 4.3.8 Water quality monitoring 4.3.9 Chemical analysis 4.3.10 Statistical analysis 29 30 30 30 30 33 33 34 34 35 36 36 5 5.1 5.2 5.3 Summary of major results Chemical composition of feed ingredients Chemical composition of diets Feed digestibility 5.3.1 Digestibility of diets 5.3.2 Digestibility of feed ingredients Growth performance and feed utilisation Carcass and body indices (Papers IV & V) Water quality and plankton monitoring 5.6.1 Water quality monitoring 5.6.2 Plankton monitoring and assessment 37 37 39 39 39 43 45 47 48 48 48 General discussion Feed and feeding in small-scale striped catfish farming Potential feed ingredient resources for striped catfish 6.2.1 Plant feed ingredients 6.2.2 Animal feed ingredients Nutrient digestibility of potential local feeds in striped catfish Replacing fish meal with locally available feed resources 51 51 51 52 52 53 55 General conclusions and applications Conclusions Implications and further research 7.2.1 Implications 7.2.2 Future research 59 59 60 60 60 5.4 5.5 5.6 6 6.1 6.2 6.3 6.4 7 7.1 7.2 References 61 Acknowledgements 77 List of Publications This thesis is based on the work contained in the following papers, referred to by Roman numerals in the text: I Da, C.T., Hung, L.T., Berg, H., Lindberg, J.E and Lundh, T (2011) Evaluation of potential feed sources, and technical and economic considerations of small˗scale commercial striped catfish (Pangasianodon hypophthalmus) pond farming systems in the Mekong Delta of Vietnam Aquaculture Research (doi:10.1111/j.1365˗2109.2011.03048.x), 1–13 II Da, C.T., Lindberg, J.E and Lundh, T (2012) Digestibility of dietary components and amino acids in plant protein feed ingredients in striped catfish (Pangasianodon hypophthalmus) fingerlings Aquaculture Nutrition (doi:10111/anu.12011), 1–10 III Da, C.T., Lundh, T and Lindberg, J.E (2012) Digestibility of dietary components and amino acids in animal and plant protein feed ingredients in striped catfish (Pangasianodon hypophthalmus) fingerlings (Submitted to Aquaculture Nutrition) IV Da, C.T., Lundh, T and Lindberg, J.E (2012) Evaluation of local feed resources as alternatives to fish meal in terms of growth performance, feed utilisation and biological indices of striped catfish (Pangasianodon hypophthalmus) fingerlings Aquaculture 364–365, 150–156 V Da, C.T., Lundh, T., Berg H., and Lindberg, J.E (2012) Growth performance, feed utilization and biological indices of pond˗cultured striped catfish (Pangasianodon hypophthalmus) fed diets based on locally available feed resources (manuscript) Papers I, II and IV are reproduced with the permission of the publishers Abbreviations AD ADC AIA BOD BR BW CF CFPM CMC COD CP CSLM DM DO DWG EAA EE EFA EWM FAs FCR FeM FI GAPS GE GNC HCN HSI Apparent digestibility Apparent digestibility coefficient Acid insoluble ash Biochemical oxygen demand Broken rice Body weight Crude fibre Catfish by-product meal Carboxymethyl cellulose Chemical oxygen demand Crude protein Cassava leaf meal Dry matter Dissolved oxygen Daily weight gain Essential amino acids Ether extract Essential fatty acid Earthworm meal Fatty acids Food conversion rate Feather meal Feed intake (total) per fish Golden apple snail Gross energy Groundnut cake Hydrogen cyanide Hepato-somatic index IPF KI N NDF OM P PBM PER PI RB SBM SFAs SGR SPLM SR TAG TAN TN TP TSS VSI WG Intra-peritoneal fat index Kidney index Nitrogen Neutral detergent fibre Organic matter Phosphorus Poultry by-product Protein efficiency ratio Protein intake Rice bran Soybean meal Saturated fatty acids Specific growth rate Sweet potato leaf meal Survival ratio Triacylglycerols Total ammonia nitrogen Total nitrogen Total phosphorus Total suspended solids Viscera somatic weight index Weight gain 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 11 Discussion We have shown previously indoor conditions that fish meal protein can be replaced with protein from locally available plant and animal ingredients in feed for striped catfish fingerlings without compromising growth performance, feed utilisation or carcass traits (Da et al., 2012) The data in the present study on striped catfish fingerlings, cultured in earthen ponds, largely confirm those previously findings In both studies, the fingerlings were fed identical diets where fish meal CP was replaced with CP from sweet potato leaf meal (20% replacement), cassava leaf meal (25% replacement), groundnut cake (25% replacement), soybean meal (100% replacement), golden apple snail meal (100% replacement) and shrimp head meal (100% replacement) However, fish growth performance (final BW, WG, DWG) on most diets fed to fingerlings in earthen ponds was 4˗ to 5˗fold higher and the SGR was about 2˗fold higher compared with the performance recorded in the indoor experiment (Da et al., 2012) The WG and DWG in the present study were also 4˗ to 6˗fold higher than values reported for striped catfish and Asian catfish species cultured under other laboratory conditions (Phumee et al., 2011; Hung et al., 2003) In addition, FCR was 0.2˗0.4 units (kg feed/kg BW gain) higher for fingerlings cultured in earthen ponds compared with those cultured indoors (Da et al., 2012) This can partly be explained by the higher growth rate, which reduced the impact of the energy maintenance costs on the FCR However, the majority of the improvement in FCR can be explained by the pond environment and the potential supply of nutrients from algae and other water organisms The pond water contained approximately 11,360 to 49,000 individuals/L of micro-algae and 1,000 to 7,650 individuals/L of zooplankton Phytoplankton are consumed by zooplankton, which can then serve as live feed for fish (Aqua SA, 2003) Altogether, this comprises a substantial amount of biomass with potential nutrients and, if consumed by the fish this would make a significant contribution to their energy and nutrient supply The improved FCR in the outdoor cultured striped catfish fingerlings compared with those cultured indoors (Da et al., 2012) gives an indication of the quantitative importance of this biomass for fish nutrient supply and subsequent performance In general, the chemical composition and amino acid profile of test feed ingredients were in good agreement with published data (Nguyen et al., 2012; Tram et al., 2011; Hue et al., 2010; Phuc & Lindberg, 2001; Phuc & Lindberg, 2000) Except for the rice bran diet, the average CP content of the diets studied was 22.7% CP within the range (19˗30% CP) required for normal growth rate in Pangasius fingerlings, but lower than the range required (27˗32% CP) for maximum growth rate (Hung et al., 2002) The dietary CP content was comparable to that reported for commercial striped catfish farms, which is on average 26% CP (range 20˗30%) for commercial feeds and 22% CP (range 17˗26%) for farm-made feeds (Phan et al., 2009) Except for the rice bran diet, the dietary content (g/kg DM) of arginine (13.2˗14.8), histidine (3.2˗6.4), leucine (16.0˗17.6), methionine (4.0˗5.9), phenylanine (9.1˗10.6 ) and valine (9.5˗10.5) was above the requirements of channel catfish (Wilson et al., 1980) Moreover, the dietary content (g/kg DM) of lysine (6.6˗9.3), threonine (5.7˗7.7) and isoleucine (9.0˗10.2) met the requirements of channel catfish (Wilson, 1989) Almost all EAA profiles in the diets tested in the present study were high compared with the EAA recommendations for tilapia (Jackson & Capper, 1982) and common carp (Schwarz & Kirchgessner, 1988) Interestingly, the striped catfish fingerlings fed the rice bran diet were able to consume almost as much feed (290 g) as the fingerlings fed the reference diet and the other test diets (305˗360 g) This very clearly demonstrates the omnivorous nature of striped catfish and their great capacity to feed on plant material However, as expected, the growth performance was impaired on the rice bran diet and the FCR was much higher than on the other diets This was due to poor CP and EAA supply (Hung et al., 2002) in this diet and the lower digestibility of energy in rice bran (Da, Lundh and Lindberg, unpublished data) than in the other test ingredients Except for the diet with rice bran, there were only minor differences between the reference diet and the test diets in terms of feed intake, protein intake, FCR, protein utilisation and survival ratio The final BW, WG, DWG and SGR were highest for the shrimp head meal and the reference diets, followed by the diets with golden apple snail meal, groundnut cake and sweet potato leaf meal However, when cassava leaf meal and soybean meal replaced fish meal in the diet there were numerical reduction in final BW, DWG and SGR, and an increase in FCR compared with fish fed the other diets The poor growth performance and high FCR on the soybean meal diet was unexpected, as earlier studies have found that the digestibility of soybean meal is high in hybrid catfish (Tram et al., 2011), Tra catfish (Hien et al., 2010) and striped catfish (Da, Lundh & Lindberg, unpublished data) However, Phumee et al (2011) reported reduced growth performance of juvenile striped catfish and impaired feed utilisation in diets with increasing soybean meal inclusion The poorer growth performance and FCR on the soybean meal diet could be related to disturbed gut function (Nordrum et al., 2000) due to the presence of anti-nutritional factors It could also be partly due to a lower supply of sulphurcontaining amino acids in this diet than in the other diets As mentioned earlier, the growth performance in the present study was very high (4˗ to 5˗fold higher) than in our earlier study on striped catfish fingerlings fed the same diet under indoor conditions (Da et al., 2012) Thus, it is reasonable to assume that any 10 negative effect on the biology of the fingerlings of including soybean meal in the diet would manifest itself more clearly when feed intake and growth rate are high than when they are low The data indicate that inclusion of soybean meal should be restricted in the diets of striped catfish fingerlings to avoid negative impacts on growth performance and FCR The CP and amino acid supply with the cassava leaf meal diet was similar to that with the other diets and the EAA profile was comparable However, the lower digestibility of CP and EAA in cassava leaf meal in striped catfish fingerlings (Da, Lundh & Lindberg, unpublished data) than in the other test ingredients would be expected to have a negative impact on performance Moreover, cassava leaves contain cyanogenic glycosides and although the content in fresh cassava leaves is reduced by more than 80% by sun-drying and cooking (Hue et al., 2010; Phuc & Lindberg, 2001), a negative impact on fish performance cannot be ruled out The FCR in the present study was comparable to that reported for juvenile African catfish (Fagbenro, 2004) and on striped catfish on commercial farms (Phan et al., 2009), but better than values reported for juvenile Asian catfish and iridescent shark (Pangasius) (Liu et al., 2011; Hung et al., 2004; Hung et al., 2003) Moreover, the PER was high in the present study compared with values reported for juvenile African catfish fed plant protein (Nyina-wamwiza et al., 2007; Fagbenro, 2004), red-tailed catfish species (Deng et al., 2011) and juvenile Asian catfish species (Phumee et al., 2011; Hung et al., 2004) This indicates that the amino acid supply and amino acid profile in the test diets was adequate for striped catfish requirements The groundnut cake diet (25% replacement of fish meal) supported a comparable growth performance and FCR as the reference diet Similarly, Ovie (2010) found that groundnut cake could replace 10% of fish meal in the diet of vundu (Heterobranchus longifilis) without any negative effects on performance Jackson et al (1982) reported that groundnut cake can replace 50% of the fish meal in the diet of tilapia (Sarotherodon mossambicus), whilst growth performance is impaired at higher levels of inclusion The major limiting factors in groundnut cake are the low content of lysine and methionine, and the presence of aflatoxins and anti-nutrient compounds (Ovie, 2010; Jackson et al., 1982) The highest growth performance was found on the shrimp head meal diet, and FCR for this diet was comparable to that for the reference diet These results are in agreement with earlier studies on the utilisation of shrimp head meal, shrimp processing by-products and shrimp head silage, which showed high growth performance in pigs (Fanimo et al., 2004; Ngoan, 2000), ducks 11 (Dong, 2005) and African catfish (Phonekhampheng, 2008; Nwanna et al., 2004; Nwanna, 2003) fed these products The growth performance and FCR for the golden apple snail meal diet was comparable to that for the reference diet Golden apple snails have for many years been used as the main protein source for tiger prawns (Penaeus monodon) (Bombeo-Tuburan et al., 1995), giant freshwater prawns (Jintasataporn et al., 2004) and tilapia (Catalma et al., 1991) The golden apple snail is considered a pest in rice fields in Vietnam and can be found in large amounts in most waters in the Mekong Delta The moisture, protein and lipid content of the fillet from the fish in the present study was comparable to that in exported fillet of striped catfish from Vietnam (Elena et al., 2008) The lipid content in fish liver at the end of experiment was 3˗ to 5˗fold higher than the initial values and that in fish fillet and kidney The high fat content in the liver can be explained by it being the major storage site for lipids (Guillaume, 2001; Segner & Böhm, 1994) The HSI, IPF and VSI indices in present study were lower than those reported previously for Asian catfish species (Phumee et al., 2011; Hung et al., 2003) The HSI index was higher for the groundnut cake, golden apple snail meal and shrimp head meal diets than for the reference diet Peres & OlivaTeles (2008) demonstrated a correlation between HSI index and lysine level in the diet of turbot (Scophthalmus maximus) juveniles, with a linear decrease in HSI index with increased dietary lysine level This relationship could not be confirmed in the present study It has also been suggested that diets containing high amounts of carbohydrates should result in higher HSI index (Hernández et al., 2007; Hung et al., 2003) However, the rice bran diet, which had the highest carbohydrate content, resulted in a comparable HSI to the diets with shrimp head meal and golden apple snail meal Except for the rice bran diet, the diets in the present study had similar carbohydrate content, but with some differences in the relative proportions of fibre and non-fibre fractions The utilisation of the non-fibre fraction may have differed between diets The highest VSI index in the present study was found on the rice bran and golden apple snail meal diets, followed by the shrimp head meal and soybean meal diets and with the lowest values for the reference diet and the diets with groundnut cake, cassava leaf meal and sweet potato leaf meal There were no differences in feed intake between diets and no obvious differences in diet composition that can explain the effect on the VSI index Hernández et al (2007) reported that IPF index is closely related to the digestible energy intake of sharpsnout seabream (Diplodus puntazzo), a finding that cannot be confirmed by the results in the present study 12 The average water temperature was 28.6 °C, with a pH value of 7.8 (range 6.7˗8.2) and a DO content of 7.0 (range 5.4˗7.2 mg/L) The average concentrations of BOD (19.8 mg/L), COD (43.4 mg/L), TAN (0.4 mg/L), NO2– (0.1 mg/L) and NO3– (0.07 mg/L) were low compared with the limits recommended in National Standards (TCVN 5942, 1995) In general, the water quality was good throughout the experiment and the values recorded can be considered low compared with the results of water quality monitoring in striped catfish farms in the Mekong Delta (Phuong et al., 2010) The average density in water of phytoplankton was 29,661 (11,359˗48,857) individuals/L and the average density of zooplankton was 3,530 (1,002˗7,651) individuals/L This was 5˗ to 3˗fold higher than the densities of phytoplankton and zooplankton found in river water (Phuong et al., 2010) Conclusions Fish meal protein in feed for striped catfish (Pangasianodon hypophthalmus) fingerlings can be replaced by protein from locally available plant and animal feed ingredients without compromising growth performance, feed utilisation or carcass traits However, the extent of replacement will depend on the properties of the individual feed ingredient Further studies on grow-out fish are warranted to confirm the present findings, and to quantify the impact on fish performance and product quality traits under commercial conditions Acknowledgements The authors wish to thank the Sida/SAREC MEKARN (“Mekong Basin Animal Research Network”) project for funding the research and a PhD scholarship for Chau Thi Da The authors also wish to thank the laboratory staff of the National Institute of Animal Husbandry, Ministry of Agriculture and Rural Development, Vietnam, and Mr Huynh Thanh Phuong and Mr Le Van Kha, students at the Aquaculture Department, Faculty of Agriculture and Natural Resources, An Giang University, Vietnam, for their support and assistance during this study 13 Table Ingredient composition of reference diet (RD) and test diets (g/kg) for striped catfish (Pangasianodon hypophthalmus) fingerlings Test diets RD Groundnut cake Cassava leaf meal Sweet potato leaf meal Soybean meal Golden apple snail meal Shrimp head meal Rice bran Fish meal 260 195 195 208 0.0 0.0 0.0 0.0 Vegetable protein mix 480 480 400 400 450 480 480 0.0 Wheat flour 200 200 200 200 200 220 260 0.0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Groundnut cake – 65 – – – – – – Cassava leaf meal – – 145 – – – – – Sweet potato leaf meal – – – 132 – – – – Soybean meal – – – – 290 – – – Golden apple snail meal – – – – – 240 – – Shrimp head meal – – – – – – 200 – Rice bran – – – – – – – 940 Rate of replacement of fish meal (FM) (%) 25 25 20 100 100 100 100 Squid liver oil Vit-min premix CMC Commercial product used for striped catfish feed in the Mekong Delta of Vietnam The product is based on soybean and rice products and contains (% of DM): CP 21.2%, EE 7.6%, NDF 25.5%, ash 3.1% Vitamin and mineral premix; content per kg: vitamin A 4.000.000 UI; vitamin D3 800.000 UI; vitamin E 8.500 UI; vitamin K3 750 UI; vitamin B1 375 UI; vitamin C 8.750 UI; vitamin B2 1.600 mg; vitamin B6 750 mg; folic acid 200 mg; vitamin B12 3.000 mcg; biotin 20.000 mcg; methionine 2.500 mg; Mn, Zn, Mg, K and Na 10 mg Carboxymethyl cellulose (CMC): Imported from Korea 14 Table Chemical composition (g/kg DM), gross energy (MJ/kg DM) and amino acid (g/kg DM) content of test ingredients Groundnut cake Cassava leaf meal Sweet potato leaf meal Soybean meal Golden apple snail meal Shrimp head meal Rice bran Crude protein 316 223 166 485 564 661 144 Lipid 100 65 24 10 16 36 126 Crude fibre 41 145 14 35 10 61 37 NDF 342 339 397 198 239 242 217 Ash 55 97 170 73 118 143 79 Gross energy 19.5 18.9 14.6 17.8 12.3 16.6 18.2 Essential amino acids Arginine 27.9 11.1 7.7 24.9 32.1 38.2 8.2 Histidine 5.0 3.4 1.9 4.8 11.9 11.1 1.9 Isoleucine 12.0 10.7 7.5 18.3 18.8 20.9 5.4 Leucine 19.8 17.2 10.9 29.1 36.2 37.2 8.7 Lysine 5.2 6.7 2.6 15.1 16.3 25.5 2.9 Methionine 4.0 5.2 4.3 6.4 10.9 14.5 2.8 Phenylalanine 13.8 10.6 7.6 18.6 16.4 19.0 5.9 Threonine 6.7 8.4 5.0 14.2 11.1 9.0 4.5 Valine 13.6 11.5 8.7 18.3 20.8 19.3 5.8 Total 108.0 84.8 56.2 149.7 174.5 194.7 46.1 Non-essential amino acids Aspartic acid 18.8 22.4 14.6 32.8 35.1 22.3 7.2 Glutamic 59.4 28.4 19.3 77.6 69.0 65.5 18.1 Serine 13.9 8.0 4.2 16.9 17.9 15.7 4.8 Alanine 11.7 12.0 8.9 16.3 31.3 28.2 6.6 Glycine 11.8 7.7 5.1 10.9 24.1 22.9 4.2 Proline 12.3 10.7 6.9 24.6 16.3 24.7 6.8 Tyrosine 9.6 7.8 7.3 15.2 17.8 16.0 4.7 Total 137.5 97.0 66.3 194.3 211.5 195.3 52.4 15 Table Chemical composition (g/kg DM), and gross energy (MJ/kg DM) and amino acid (g/kg DM) content of the reference diet (RD) and test diets Test diets (% of fish meal crude protein replaced) RD Groundnut cake (25%) Cassava leaf meal (25%) Sweet potato leaf meal (20%) Soybean meal (100%) Golden apple snail meal (100%) Shrimp head meal (100%) Rice bran (100%) Crude protein 225 230 227 223 234 227 225 124 Lipid 45 39 44 38 35 31 35 106 Crude fibre 29 45 51 51 37 53 59 84 NDF 166 242 261 278 201 253 259 290 Ash 102 81 73 84 41 41 89 72 Gross energy 16.2 16.7 17.1 16.5 17.2 16.8 15.9 17.6 Ca 15.6 17.4 13.6 13.8 1.0 5.2 20.9 2.2 Na 3.5 2.3 3.2 3.7 1.1 1.5 6.5 1.3 K 12.1 11.2 12.1 14.6 20.5 10.4 9.5 20.5 Mg 0.4 0.4 0.5 0.5 0.4 0.4 0.5 0.6 Essential amino acids Arginine 14.8 14.7 13.4 13.2 13.7 14.6 14.7 7.7 Histidine 6.4 5.6 5.5 5.5 3.2 4.8 4.2 1.8 Isoleucine 9.7 9.3 9.3 9.0 10.2 9.7 9.5 5.0 Leucine 17.6 16.6 16.6 16.0 16.5 17.3 16.3 8.1 Lysine 9.3 8.0 8.2 7.9 6.9 6.6 7.8 2.7 Methionine 5.9 5.3 5.4 5.4 4.0 4.9 5.3 2.6 Phenylalanine 9.8 9.7 9.5 9.1 10.6 9.6 9.6 5.5 Threonine 6.3 6.1 6.3 5.8 7.7 6.6 5.7 4.2 Valine 10.5 10.1 10.1 9.8 10.5 10.5 9.5 5.4 Total 90.3 85.4 84.3 81.7 83.3 84.6 82.6 43.0 Non- essential amino acids Aspartic acid 19.5 18.7 19.0 18.0 20.2 19.9 16.1 6.8 Glutamic 39.0 38.8 36.0 35.3 44.2 39.8 37.3 17.1 Serine 8.4 8.3 7.9 7.4 9.0 8.7 7.6 4.5 Glycine 13.1 11.4 11.3 11.3 6.2 9.0 7.9 4.0 Alanine 14.6 13.0 13.2 13.1 9.6 12.8 11.0 6.2 Proline 13.5 12.7 12.6 12.3 14.1 11.4 12.8 6.4 Tyrosine 8.5 8.1 8.0 8.0 8.4 8.5 7.6 4.4 Total 116.6 111.0 108.0 105.4 111.7 110.1 100.3 49.4 16 Table Growth performance and feed utilisation of striped catfish (Pangasianodon hypophthalmus) fingerlings fed the reference diet (RD) and the test diets Test diets (% of fish meal crude protein replaced) RD Initial BW Final BW WG (g) 16.1 ab 229.4 ab Groundnut cake (25%) Cassava leaf meal (25%) Sweet potato leaf meal (20%) Soybean meal (100%) Golden apple snail meal (100%) Shrimp head meal (100%) Rice bran (100%) SEM P-value 16.9 16.2 16.1 16.2 16.2 16.2 16.1 b 219.0 b 213.3 202.1 ab b DWG (g) 1.90 SGR (%) 2.35ab 1.81 c 177.9 c 161.7 1.44 c 2.28b 2.10c 1.58 b 1.97 b 2.94 a 2.35 a 0.74 a 0.79 a bc 204.9 bc d 132.5 d b 222.3 b 188.8 116.3 206.1 bc d b 1.69 2.20bc 2.75 a 0.78 a 2.10 b 2.69 a 0.84 a 1.84 2.32ab 1.54 b 3.15 a 0.69 a 7.45 0.02 e 7.39 0.01 e 0.07 0.02 2.45a 1.47e 0.04 0.03 1.42 b 4.47 a 0.29 0.02 3.18 a 0.84 b 0.27 0.01 0.77 a 0.36 b 0.04 0.03 257.0 a 240.8 2.15 a 83.8 67.7 0.60 1.66 2.96 a PI 0.73 a FI 326.1 320.8 347.3 351.7 359.1 305.5 340.0 293.9 7.89 0.71 SR (%) 95.2 93.2 90.5 96.3 92.5 93.5 95.2 92.2 0.74 0.62 PER 1.68 1.87d 1.00 b FCR b 1.04 0.42 e a BW (g): body weight; WG: weight gain; DWG: daily weight gain; SGR: specific growth rate; FCR: feed conversion ratio; PER: protein efficiency ratio; PI: protein intake; FI: total feed intake per fish; SR: survival ratio SEM = Standard error of the mean Means within rows with different superscript letters are significantly different (P