CAN THO UNIVERSITY COLLEGE OF AQUACULTURE AND FISHERIES EVALUATE POTENTIAL USE OF GUT WEED (Enteromorpha sp.) AS A FOOD SOURCE FOR TILAPIA (Oreochromis niloticus): AFFECT ON SURVIVAL AND GROWTH By DAM PHUOC HIEN A thesis submitted in partial fulfillment of the requirements for The degree of Bachelor of Aquaculture Can Tho City, December 2012 CAN THO UNIVERSITY COLLEGE OF AQUACULTURE AND FISHERIES EVALUATE POTENTIAL USE OF GUT WEED (Enteromorpha sp.) AS A FOOD SOURCE FOR TILAPIA (Oreochromis niloticus): AFFECT ON SURVIVAL AND GROWTH By DAM PHUOC HIEN A thesis submitted in partial fulfillment of the requirements for The degree of Bachelor of Aquaculture Promoter Dr NGUYEN THI NGOC ANH Can Tho City, December 2012 ACKNOWLEDGE I would like to express my deep gratitude to my promoter Dr Nguyen Thi Ngoc Anh for constant guidance and enthusiastic help during conducting experiment and her patience in correcting thesis Special acknowledgements to teachers of College of Aquaculture and Fisheries, Can Tho University have taught me the experiences during study I especially thanks to my classmates from Advanced Aquaculture course 34 and Aquaculture course 35 Always facilitating and enthusiastically helping me complete the thesis i ABSTRACT Two experiments were performed to assess the potential use of gut weed (Enteromorpha sp.) as a feed for tilapia (Oreochromis niloticus) In the first experiment, dried gut weed was used as a drect feed to replace pellet feed for feeding tilapia juvenile, consisting of treatments: pellet feed everyday as a control, day pellet feed_1 day dried gut weed, day pellet feed_2 day dried gut weed and dried gut weed everyday In the second experiment, a control diet containing fishmeal as main protein source was compared with five experimental diets in which fishmeal protein was replaced by increasing dietary levels of gut weed protein, respectively, 10%, 20%, 30%, 40% and 50% in practical diets for tilapia fry All experimental diets were formulated to be equivalent in crude protein (30%) and lipid (7%) Triplicate groups of fish with average initial weight of 3.04g and 0.33 g in the first and second experiment, respectively Tilapia were stocked in the 120L-composite tanks for the first experiment and in the 70L-plastic tanks for the second experiment at a density of 30 fish per tank and in seawater at salinity of ppt Fish were fed to satiation twice a day for 42 days At the end of the feeding trials, survival of experimental fish in two experiments was not affected by the feeding treatments ranging from 82.0 to 84.4% and 100% for the first and the second experiments, respectively The results in the first experiment showed that growth performance of the experimental fish fed day pellet feed_1 day dried gut weed was comparable to the group fed single pellet feed Moreover, using gut weed as direct feed can maintain better water quality and reduce the feed costs The results of the second experiment showed that mean final body weight and specific growth rate and Daily weight gain increased with increasing gut weed protein level in the fish diet up to 20% Increasing the level of gut weed protein in the diet from 30 to 40% did not exert any additional advantage in terms of growth of fish and an inclusion level of 50% led to negative effects on growth Based on the present study, it is concluded that gut weed has a great potential as alternative ingredients in diets and inclusion level up to 40% have no adverse effect on growth, feed utilization ii TABLE OF CONTENTS Contents Page ACKOWLEDGE i ABSTRACT ii TABLE OF CONTENTS iii LIST OF TABLES vii LIST OF FIGURES viii LIST OF ABBREVIATIONS viiii Chapter INTRODUCTION 1.1 Introduction 1.2 Research objectives 1.3 Research contents Chapter LITERATURE REVIEW 2.1 Gut weed 2.1.1 Classification 2.1.2 Morphology of Enteromorpha sp 2.1.3 Distribution iii 2.1.4 Nutritional value of gut weed Enteromorpha 2.1.5 Use of gut weed in aquaculture 2.2 Tilapia 2.2.1 Production of Tilapia in the world and in Vietnam 2.2.2 Classification and habitat 2.2.3 Nutritional requirement Chapter 11 MATERIALS AND METHODS 11 3.1 Study subject 11 3.2 Materials and chemicals 11 3.3 Research methodologies 11 3.3.1 Experiment Evaluating the effect of dried gut weed (Enteromorpha sp.) as direct food to replace pellet feed for feeding fingerling Tilapia 11 3.3.2 Experiment 2: Evaluating the effect of fishmeal replacement with gut weed (Enteromorpha sp.) as a protein source in practical diets for Tilapia 15 Chapter 20 RESULTS AND DISCUSSION 20 4.1 Experiment 1: Evaluating the effect of dried gut weed (Enteromorpha sp.) as direct food to replace pellet feed for feeding fingerling Tilapia 20 4.2 Effects of using dried gut weed (Enteromorpha sp.) as direct food to replace pellet feed on Tilapia performance 21 iv 4.2.1 Survival 21 4.2.2 Growth performance 22 4.2.3 Feed conversion ratio (FCR) 24 4.2.4 Cost reduction of replacing gut weed Enteromorpha sp in diets 25 4.3 Experiment 2: Effect of protein fishmeal replacement with gut weed protein on Tilapia performance 26 4.3.1 Water quality 26 4.3.2 Survival and Growth performance 27 4.3.3 Feed conversion ratio (FCR) 29 4.3.4 Economic comparison of feed cost 30 Chapter 31 CONCLUSION AND RECOMMENDATION 31 5.1 Conclusion 31 5.2 Recommendation 31 REFERENCES 32 v LIST OF TABLES Table 1: Proximate composition (% dry matter) of the experimental diets 13 Table 2: Proximate composition of ingredients used for experimental diets (% dry matter)……………………………………………………………………………………17 Table 3: Ingredients and proximate analysis of the experimental diets (% dry matter) 18 Table 4: Average water temperature and pH during 42 days in experiment 20 Table 5: Average concentration of TAN and NO2 in experiment 21 Table 6: Mean initial weight, mean final weight, weight gain, specific growth rate (SGR) and daily weight gain (DWG) of Tilapia in experiment 23 Table 7: Feed conversion ratio in the Experiment 24 Table 8: The expenditure of commercial feed combined feed with dried gut weeds to replace in diets of tilapia in the Experiment 25 Table 9: Temperature and pH during 42 days of experiment 26 Table 10: Total Ammonia Nitrogen (TAN) and Nitrite (NO2) during 42 days of Experiment 27 Table 11: Survival and growth performance of Tilapia fry fed different diets over 42 days………………… .28 Table 12: Feed cost for Tilapia growth in the Experiment 30 vi LIST OF FIGURES Figure 1: Morphology of Enteromorpha species Figure 2: Experimental system 12 Figure 3: Experimental system 16 Figure 4: Survival rate of Tilapia fed the first experiment diets after 42 days 22 Figure 5: Feed conversion ratio in the Experiment 29 vii LIST OF ABBREVIATIONS GW Gut weed WG Weight gain CF Commercial feed DGW Dried gut weed DWG Daily weight gain SGR Specific growth rate FCR Feed conversion ratio TAN Total ammonium nitrogen viii day, followed by the treatment of 1CF-1DGW and 1CF-2DGW While the lowest value of TAN (0.26 mg/L) and NO2 (0.33 mg/L) was found in the group fed single dried gut weed (DGW) These result indicated that combined feeding commercial feed with dried gut weed can maintain better water quality in the culture tank than using single commercial feed According to Boyd (1990), suitable level of TAN for aquatic animals is between 0.2-2 mg/L Truong Quoc Phu (2006) reported that overfeeding combined with the waste products of the fish are the main cause of the increasing ammonia concentration in the water Nitrite Nitrogen is the form of the protein is very toxic to aquatic species In aquaculture ponds, nitrite concentration is up to 0.5 mg/L, which can cause slow growth or can be harmful to fish The author suggested that NO2 level should be maintained a level less than 0.1 mg/L However, in salt water, chloride will reduce the concentration of NO2-N limiting toxic to fish Fish cultured at 16 ppt salinity may allow concentration of NO2-N up to 5.5 mg / L (Truong Quoc Phu, 2006) Therefore, water quality parameters in this experiment were in the acceptable range for growth of Tilapia Table 5: Average concentration of TAN and NO2 in experiment N-NO-2 (mg/L) Treatment TAN (mg/L) CF 0.50±0.05 1.10±0.12 DGW 0.26±0.04 0.33±0.06 1CF-1DGW 0.46±0.04 0.98±0.15 1CF-2DGW 0.33±0.03 0.61±0.21 4.2 Effects of using dried gut weed (Enteromorpha sp.) as direct food to replace pellet feed on Tilapia performance 4.2.1 Survival After 42 days of feeding trial, survival of experimental fish was not significantly different among treatments (P>0.05), ranging from 82.0 to 84.4% (Fig 4) 20 100 90 84.3 83.7 82 84.4 CF DGW 1CF_1DGW 1CF_2DGW S u r v i v a l r a te (% ) 80 70 60 50 40 30 20 10 Treatment Figure 4: Survival rate of Tilapia fed the first experiment diets after 42 days The result in this study is in agreement with the study of Nguyen Thi Ty Ni (2012), who assessed the fresh gut weed as direct food to substitute the commercial feed for spotted scat (Scatophagus argus) and obtained survival between 86.7 – 93.3% Author confirmed that using single gut weed or combined with commercial feed did not affect survival of this species Similar experiment was conducted by Ho Tuyet Cuong (2012), using dried gut weed for feeding red Tilapia (Oreochromis sp.), survival of fish was similar among treatments 4.2.2 Growth performance The growth rate depends on the nutritional condition, environment and development stages of fish The growth of fish is an important factor used to assess the quality of fish feed intake In aquaculture, besides management of good water quality, feed is extremely important factor supporting fish to grow rapidly, limit investment costs, and contribute to increase production efficiency 21 Table 6: Mean initial weight, mean final weight, weight gain, specific growth rate (SGR) and daily weight gain (DWG) of Tilapia in experiment Treatment Initial weight Final weight (g) (g) CF 3.04±0.48 11.92±1.79c 8.88±1.73c 3.22±0.40c 0.212±0.04c 1CF-1DGW 3.04±0.48 11.62±1.29c 8.85±1.21c 3.18±0.27c 0.205±0.03c 1CF-2DGW 3.04±0.48 9.77±2.07b 6.73±2.04b 2.73±0.51b 0.160±0.05b DGW 6.11±1.33a 3.07±1.33a 1.55±0.52a 0.073±0.03a 3.04±0.48 Weight gain SGR (%/day) DWG (g/day) (g) Values are mean ± standard deviation Mean values in each column bearing different superscripts are significantly different (P[...]... encourage farmers using local availability of gut weed as food source for tilapia or other fish in the Mekong delta and it could contribute to reduce feed costs and improve profits for farmers 1.3 Research contents Effects of dried gut weeds (Enteromorpha sp.) as food source on survival and growth rate of Tilapia (Oreochromis niloticus) Effects of fishmeal replacement with gut weed (Enteromorpha sp.) as a. .. reduction in treatment 1 day on commercial feed and 2 days on dried gut weed is more than in the treatment 1 day on commercial feed and 1 day on gut weed However, the growth of Tilapia in the treatment 1 day on commercial feed and 2 days on gut weed is 24 lower and statistical significance compared to control treatment So, gut weed can replace pellets with frequency of 1 day on commercial feed and 1 day on. .. El Sayed (1999), evaluated seaweeds as food source for Tilapia, author revealed that tilapia is able to absorb 70-80% of green algae that some fish species are unlikely to digest Yousif, et al (2004) evaluated the dehydrated Enteromorpha incorporated at a rate of 0 (control), 10, 20 and 30% in the diets for rabbitfish, Siganus canaliculatus (Park) They found that the survival, growth performance and. .. prolifera can reach at least 15% without affecting the growth and still maintain a high survival rate for this fish species Swain and Padhi (2011), evaluated the nutritional value of four seaweeds such as Enteromorpha intestinalis, Grateloupia filicina, Gracilaria verrucosa and Polysiphonia sertularioides which were added at various induction levels in the diets fed to juvenile Rohu (Labeo rohita) and. .. economic and can live in fresh and brackish water (Sayed, et al., 2006) 1 Consequently, investigating the potential use of gut weed (Enteromorpha sp.) as feed for Tilapia was implemented 1.2 Research objectives Determine suitable percentage of fish meal protein replaced by gut weed protein (Enteromorpha sp.) in a practical diet and gut weed as direct feed to substitute a commercial feed for Tilapia. .. revealed that gut weed (Enteromorpha sp.) belonging to green algae distribute abundantly in the extensive shrimp farms and other brackish water bodies of the Mekong delta (SUDA, 2009) This indicates large quantity of gut weed is available for aquaculture feeds So far, in Vietnam study on the utilization of gut weed for fish has not been greatly considered In the other hand, one of the great advantages... phosphorus) of fish carcass in all treatments was similar except the lipid and calcium levels in the treatments of 40 and 50% substitution were significantly lower compared to the control treatment 2.2 Tilapia 2.2.1 Production of Tilapia in the world and in Vietnam Tilapia is one of the most widely cultured fish in the world such as China, Taiwan, Brazil, Africa, and Costa Rica… Currently, farmed tilapia represents... alternative plant protein sources such as soybean meal, seaweed meal or other sources that may reduce the use of fishmeal in feeds is necessary (FAO, 2011) Among alternative plant protein sources, seaweeds may be considered as a suitable ingredient for replacing fishmeal in fish and shrimp diets because of its high nutritional value (FAO, 2003; Dhargalkar and Pereira, 2005) Like other seaweeds, gut weed Enteromorpha... the main tilapia producing country, alone produces 1.2 million, while the rest of Asia contributes 0.9 million tones Total tilapia production is mainly Nile tilapia (Oreochromis niloticus) All new countries entering tilapia production concentrate on this species, which is easy to grow In 2008, about three quarters of world Tilapia production were Nile Tilapia Production of Tilapia in Vietnam has been... Table 10 showed that the concentration of TAN and NO2 were not much different among feeding treatments ranging from 0.22-0.40 mg/L and 0.29-0.45 mg/L, correspondingly According to Truong Quoc Phu (2006), these values are in the range for normal growth of Tilapia 4.3.2 Survival and Growth performance Survival of Tilapia was not affected by the feeding treatments; all treatments had 100% survival (Table