effects of magnesiumphosphoruspotassium containing in water on molting, growth and survival rate of the white shrimp (litopenaeus vannamei) juveniles, reared in low salinity water

CAN THO UNIVERSITY COLLEGE OF AQUACULTURE AND FISHERIES EFFECTS OF MAGNESIUM-PHOSPHORUS-POTASSIUM CONTAINING IN WATER ON MOLTING, GROWTH AND SURVIVAL RATE OF THE WHITE SHRIMP (Litopenaeus vannamei) JUVENILES, REARED IN LOW SALINITY WATER By TRAN THI BE GAM A thesis submitted in partial fulfillment of the requirements for the degree of Bachelor of Aquaculture Can Tho, 12/2013 CAN THO UNIVERSITY COLLEGE OF AQUACULTURE AND FISHERIES EFFECTS OF MAGNESIUM-PHOSPHORUS-POTASSIUM CONTAINING IN WATER ON MOLTING, GROWTH AND SURVIVAL RATE OF THE WHITE SHRIMP (Litopenaeus vannamei) JUVENILES, REARED IN LOW SALINITY WATER By TRAN THI BE GAM A thesis submitted in partial fulfillment of the requirements for the degree of Bachelor of Aquaculture Supervisor MSc HUYNH TRUONG GIANG Can Tho, 12/2013 ACKNOWLEDGEMENT Foremost, I would like to express my sincere gratitude to my supervisor, MSc Huynh Truong Giang for the continuous support of my study, for his invaluable guidance, advice, encouragement, and immense knowledge His guidance helped me in all the time of research and writing of this thesis I want to dedicate my great appreciation to Ms Phan Thi Cam Tu for her kind help in finishing the research Many thanks are also giving to all other doctors of the college of aquaculture and fisheries, and especially to those of the Department of Applied Hydrobiology for providing me with great working and learning conditions I would love to express my sincere appreciation to many of my friends, especially Pham Thi Trang Nhung, Le Phuoc Dai, Bui Doan Luan, and Tran Trung Giang for their unconditionally kind help throughout the experimental period Last but not the least, I really want to thank my family for their great life-time support which makes everything possible for me Tran Thi Be Gam i APPROVEMENT The thesis “Effect of Mg-P-K levels containing in water on molting, growth, and survival rate of the white shrimp L vannamei juveniles, reared in low salinity water” was completed base on my results Supervisor’s signature Student’s signature ii ABSTRACT The objective of the present study was to evaluate the effects of several aqueous magnesium, potassium, and phosphorus on survival, growth, and molting interval of L.vannamei at salinity 2‰ The study consisted of two experiments The study consisted of two experiments For the first experiment with postlarvae 15-day, aqueous Mg-K-P were supplemented directly into water at three different levels (10-5-5; 20-1010; 40-20-20 mg/L) and a treatment with no supplemented minerals severed as the control group In the second experiment, concentrations of minerals added in the treatments were the same as the first experiment but conducted with juvenile shrimp (4.7±0.02 g) Each treatment comprised of 14 shrimp Each shrimp was individually cultured in a small net cage Fourteen small net cages were allocated in a composite tank with a capacity of m3 Molting interval, survival, growth rate were recorded Results from the first experiment indicated no significant differences (p>0.05) in survival and growth of shrimp among treatments Results from the second experiment reveal a significant difference in survival between 10-5-5 treatment (14.29%) and all other treatments (28-36%) The results showed highest weight gain (1.7±0.27 g), length gain (1.81±0.29 cm), SGR (1.71±0.35% day-1) and DWG (0.08±0.016 g day-1) in 20-10-10 treatment However, no differences in molting interval were observed These results suggest supplementation of mineral are common in low salinity water Keywords: Litopenaeus vannamei, low salinity, magnesium, phosphorus, potassium, molting iii TABLE OF CONTENTS Pages ACKNOWLEDGEMENT i APPROVEMENT ii ABSTRACT iii TABLE OF CONTENTS iv LIST OF TABLES vii LIST OF FIGURES viii LIST OF FIGURES viii LIST OF ABBREVIATIONS .ix LIST OF ABBREVIATIONS .ix Chapter .1 INTRODUCTION .1 1.1 Problem identification: .1 1.2 Objective: 1.3 Research content: .2 Chapter .3 LITERATURE REVIEW 2.1 Biological characteristics of white shrimp (Litopenaeus vannamei): 2.1.1 Classification: .3 2.1.2 Distribution: 2.1.3 Life cycle: 2.1.4 Growth characteristics: .4 2.1.5 Molting cycle: 2.1.6 Nutrition demand: .6 iv 2.2 Osmoregulation of shrimp 2.3 Effect of low salinity on the growth and survival rates of white shrimp (L.vannamei) 2.4 White shrimp (L vannamei) production in the world: .8 2.5 White shrimp (L vannamei) production in Vietnam: Chapter 10 MATERIALS AND METHODS .10 3.1 Time and location 10 3.2 Materials 10 3.2.1 Shrimp culture 10 3.2.2 Equipment and chemicals 10 3.3 Research design and experimental approaches 10 3.3.1 Experiment 1: Effects of Mg-P-K supplemented in water on growth and survival rate of white shrimp (L vannamei) 10 3.3.2 Experiment 2: Effects of Mg-P-K supplemented on molting intervals of white shrimp L vannamei (4-5 g) that reared in low salinity water .12 3.4 Data analysis 13 Chapter 14 RESULTS AND DISCUSSIONS 14 4.1 Experiment 1: Effects of Mg-P-K supplemented in water on growth and survival rate of white shrimp (L vannamei) .14 4.1.1 Water quality .14 4.1.1.1 Temperature (oC) and pH 14 4.1.1.2 Total ammonia nitrogen (TAN), Nitrite (N-NO2-), and Phosphate (PPO43-) 14 4.1.1.3 Calcium (Ca2+), Magnesium (Mg2+), Potassium (K+) concentrations and Mg:Ca ratios 15 v 4.1.2 Growth performance 16 4.1.2.1 Weight Gain (WG), Daily Weight Gain (DWG), Specific Growth Rate (SGR) .16 4.1.2.2 Length Gain (LG), Daily Length Gain (DLG), Specific Growth Rate (SGR) .17 4.1.3 Survival rate (%) 17 4.2 Experiment 2: Effects of Mg-P-K supplemented on molting intervals of white shrimp L vannamei that cultured in low salinity water 19 4.2.1 Water quality .19 4.2.1.1 Temperature, pH 19 4.2.1.2 Total ammonia nitrogen (TAN), Nitrite (N-NO2-), Phosphate (P-PO43-) 19 4.2.1.3 Calcium (Ca2+), Magnesium (Mg2+), Potassium (K+), and Mg:Ca ratios 20 4.2.2 Growth performance of white shrimp L vannamei 21 4.2.2.1 Molting intervals of white shrimp L vannamei 21 4.2.2.2 Weight gain of white shrimp after molting 22 4.2.2.3 Length gain of white shrimp after molting 23 4.2.2.4 Growth performance of white shrimp at the end of experiment 24 4.2.2.5 Survival rate 25 Chapter 27 CONCLUSIONS AND RECOMMENDATIONS 27 5.1 Conclusions 27 5.2 Recommendations 27 REFERENCES 28 vi LIST OF TABLES Table 1: Events of possible technological significance occurring in the molting cycle of shrimp .5 Table 2: Ionic composition of seawater and freshwater Table 3: Production of white shrimp in North, Central and South of Viet Nam in 20099 Table 4: Methods for water quality sampling and analysis 11 Table 5: Temperature and pH in Experiment 14 Table 6: TAN, N-NO2- and P-PO43- in Experiment 15 Table 7: K+, Mg2+ and Ca2+ concentrations in Experiment 15 Table 8: Hardness and Mg:Ca ratios for white shrimp reared in low salinity water in Experiment .16 Table 9: Growth performance indices of white shrimp L.vannamei that reared in salinity 2‰ with different Mg-K-P supplemented levels in Experiement 17 Table 10: Initial length (cm), final length (cm), daily length gain (cm day-1), specific growth rate (% day-1), and length gain (g) for L.vannamei reared in salinity 2‰ in Experiment .17 Table 11: Temperature and pH in Experiment .19 Table 12: TAN, Nitrite, and Phosphate for white shrimp reared in low salinity water in Experiment .20 Table 13: Potassium, magnesium, and calcium for white shrimp reared in low salinity water in Experiment 20 Table 14: Hardness and Mg:Ca ratios for white shrimp reared in low salinity water in Experiment .21 Table 15: Weight gain (g), daily weight gain (g day-1), specific growth rate (% day-1 ) of shrimp reared in low salinity water in Experiment 25 Table 16: Length gain (cm), daily length gain (cm day-1), specific growth rate (% day1 ) of shrimp reared in low salinity water in Experiment 25 vii LIST OF FIGURES Fig 1: White shrimp (Litopenaeus vannamei) Fig 2: Life cycle of Litopenaeus vannamei Fig.3 Net cage used in Experiment .13 Fig.4: Survival rate (%) of shrimp that reared in low salinity (2‰) at different Mg-K-P supplements Each bar represents the mean value from replicates with a standard error 18 Fig.5: Molting intervals of white shrimp (L.vannamei) 22 Fig.6: Weight gain of L.vannamei after molting .22 Fig.7: Mean weight of shrimp after each molting .23 Fig.8: Length gain of L.vannamei after each molting 23 Fig.9: Mean length of shrimp after each molting 24 Fig 10: Survival rate (%) of shrimp in Experiment .26 viii Treatment 40-20-20 4.1 4.2 4.3 W (g) L (cm) W (g) L (cm) W (g) L (cm) 1 1.06 0.6 4.5 0.62 4.3 0.4 0.7 4.5 0.38 3.4 2.2 6.5 1.1 5.5 1.2 5.9 1.1 5 1.1 0.41 3.8 0.61 4.1 0.2 0.7 5.1 0.9 4.2 1.2 5.7 1.41 5.6 0.8 4.6 1.8 6.5 1.1 5.8 0.5 3.2 0.9 0.48 0.49 3.7 10 0.76 4.6 0.61 4.3 0.56 11 0.6 4.7 1.2 5.8 0.62 4.5 12 1.1 0.52 4.2 0.3 3.9 13 0.6 0.9 5.1 0.4 4.3 14 0.9 5.1 1.5 6.2 0.6 4.4 15 0.8 0.23 2.5 0.85 4.9 16 0.3 3.5 1.4 5.2 17 0.76 4.8 0.26 3.2 0.53 4.4 18 0.2 4.6 0.67 4.7 19 0.9 4.6 0.58 4.3 0.7 4.6 20 0.28 3.5 0.8 5.4 0.76 4.4 Treatment 40-20-20 4.1 4.2 4.3 W (g) L (cm) W (g) L (cm) W (g) L (cm) 21 0.3 3.5 0.43 3.5 0.4 3.5 22 0.5 0.5 0.7 4.7 23 0.62 4.2 0.4 0.7 3.8 24 0.4 3.5 0.5 4.5 0.6 3.6 25 0.4 3.5 0.5 4.5 0.3 3.5 26 0.1 0.57 3.7 0.3 3.5 27 0.41 4.2 0.7 3.2 0.4 3.5 28 0.3 0.45 3.4 0.4 3.5 29 0.3 3.3 0.38 3.5 0.32 3.5 30 0.4 0.41 4.2 0.5 3.2 31 0.1 2.7 0.21 2.7 32 0.5 0.8 4.9 0.17 33 0.39 3.7 1.3 5.7 0.3 3.1 34 0.4 0.53 3.8 0.1 2.2 35 0.2 0.66 4.5 0.44 4.4 36 0.2 0.6 4.1 0.4 3.5 37 0.48 5.5 1.4 5.9 38 0.3 0.7 4.9 0.2 3.5 39 0.2 0.8 4.5 1.46 5.4 40 0.22 3.1 0.7 4.7 0.7 4.9 Treatment 40-20-20 4.1 4.2 4.3 W (g) L (cm) W (g) L (cm) W (g) L (cm) 41 0.4 3.3 1.2 5.9 0.6 4.6 42 0.53 3.8 0.44 0.7 4.7 43 0.32 3.6 0.3 3.5 1.1 5.4 44 0.08 2.2 0.9 0.5 4.5 45 0.91 4.7 0.5 4.5 0.5 4.3 46 1.98 6.3 0.9 5.5 0.8 4.7 47 0.67 4.5 0.3 3.5 0.6 48 0.37 3.8 0.6 4.4 0.6 4.3 49 0.5 4.3 0.3 3.4 50 0.4 3.5 Mean 0.587083 4.102083 0.7066 4.458 0.618163 4.157143 DWG 0.012935 0.091046 0.015591 0.098956 0.013626 0.09227 SGR 10.59051 4.271824 11.00228 4.456724 10.70514 4.301453 WG 0.582083 3.502083 0.7016 3.858 0.613163 3.557143 Appendix 3: Water quality parameters in Experiment Temperature and pH Treatment Control pH 10-5-5 Temp pH 20-10-10 Temp pH 40-20-20 Temp pH Temp Day M A M A M A M A M A M A M A M A 8.2 8.1 28.0 28.8 8.3 8.3 27.7 28.6 8.2 8.2 27.8 28.8 8.0 8.2 27.3 28.7 8.0 8.2 27.1 27.5 8.2 8.4 26.9 27.3 8.1 8.2 27.1 28.1 8.2 8.2 26.3 27.1 8.0 7.7 26.6 27.5 8.2 8.3 26.6 27.3 8.1 8.1 26.6 27.4 8.0 8.1 26.3 27.1 8.2 7.8 27.0 27.5 8.2 8.2 26.8 27.3 8.3 8.0 27.0 27.5 8.0 8.1 26.6 27.3 7.9 8.1 27.2 28.0 8.2 8.5 26.9 27.6 8.1 8.3 27.1 27.8 8.2 8.3 26.6 27.7 8.5 8.4 27.0 26.8 8.7 8.5 26.8 26.6 8.7 8.5 27.0 26.8 8.6 8.4 26.7 26.3 8.5 8.4 25.8 26.1 8.6 8.5 25.6 25.8 8.6 8.5 25.8 26.1 8.5 8.4 25.4 25.7 10 8.5 8.4 26.6 27.5 8.6 8.5 26.6 27.3 8.7 8.6 26.6 27.4 8.6 8.5 26.3 27.1 11 8.4 8.4 25.7 27.5 8.7 8.6 25.5 27.0 8.7 8.6 25.6 27.1 8.6 8.5 25.3 27.4 12 8.4 8.3 27.0 28.3 8.5 8.5 26.8 28.2 8.6 8.5 26.9 28.4 8.5 8.5 26.6 28.5 13 8.4 8.5 27.4 29.1 8.6 8.7 27.2 28.8 8.5 8.6 27.5 29.0 8.5 8.5 27.1 28.9 14 8.4 8.4 27.7 29.2 8.5 8.5 27.4 28.9 8.5 8.5 27.7 29.1 8.6 8.5 27.4 29.0 15 8.5 8.4 27.7 28.3 8.6 8.5 27.4 28.4 8.6 8.5 27.9 28.0 8.6 8.5 27.4 28.1 16 8.5 8.4 27.7 28.9 8.6 8.6 27.0 28.5 8.6 8.5 27.4 28.8 8.5 8.5 27.0 28.7 17 8.4 8.5 27.1 28.6 8.6 8.7 26.8 28.2 8.5 8.6 27.2 28.5 8.3 8.6 26.8 28.2 18 8.6 8.5 26.7 28.4 8.7 8.4 26.3 28.0 8.6 8.5 26.7 28.2 8.6 8.5 26.3 27.9 19 8.5 8.5 26.9 27.9 8.6 8.7 26.6 27.5 8.6 8.7 26.9 27.7 8.6 8.6 26.5 27.5 20 8.4 8.5 27.0 27.9 8.7 8.6 26.6 27.3 8.6 8.6 26.9 27.3 8.6 8.5 26.6 27.1 21 8.4 8.5 26.4 27.3 8.6 8.7 26.2 27.3 8.6 8.6 26.4 27.3 8.5 8.6 26.1 27.0 22 8.6 8.5 26.6 26.9 8.4 8.7 26.4 26.6 8.6 8.6 26.3 26.8 8.6 8.6 26.5 26.6 23 8.6 8.5 26.6 28.1 8.7 8.6 26.2 27.9 8.5 8.6 26.4 28.0 8.5 8.6 26.1 28.0 24 8.5 8.5 27.3 28.5 8.6 8.7 27.1 28.2 8.6 8.6 27.3 28.4 8.6 8.6 27.1 28.2 25 8.5 8.4 27.1 27.6 8.7 8.6 26.8 27.3 8.6 8.6 27.1 27.5 8.7 8.5 26.8 27.2 26 8.6 8.5 26.6 28.1 8.7 8.6 26.2 27.9 8.5 8.6 26.4 28.0 8.5 8.6 26.1 28.0 27 8.5 8.4 27.1 27.6 8.7 8.6 26.8 27.3 8.6 8.6 27.1 27.5 8.7 8.5 26.8 27.2 28 8.5 8.5 28.0 29.7 8.6 8.6 27.5 29.3 8.6 8.6 27.9 29.5 8.5 8.5 27.5 29.3 29 8.5 8.6 27.9 30.2 8.7 8.7 27.3 29.8 8.7 8.6 27.9 30.1 8.6 8.6 27.4 29.9 30 8.5 8.5 28.0 29.7 8.6 8.6 27.5 29.3 8.6 8.6 27.9 29.5 8.5 8.5 27.5 29.3 Day/ Treatments 20-10-10 40-20-20 377.5 400 467.5 565 370 387.5 430 535 14 333.5 336.25 388.5 520.75 21 285.5 333 355 515 28 256.5 315 337.5 504.5 36 38.2 36.4 38 Calcium 10-5-5 Hardness Control 34.4 36.2 35.4 35.6 14 33.8 34 33.8 32.7 21 32.5 32.8 31.2 31.6 28 30.7 30.7 29.2 30.3 Day/ Treatments 0.024 0.058 0.025 0.016 0.088 0.054 0.049 0.101 14 0.488 0.155 0.497 0.684 21 0.789 0.809 1.24 1.359 28 0.034 0.553 1.317 1.432 0.232 0.3065 0.259 0.201 0.7635 0.565 0.682 1.0555 14 0.282 0.8355 0.222 0.8665 21 0.1035 0.16 0.0765 0.565 28 0.075 0.0845 0.0315 0.103 0.11 5.49 8.53 14.86 Phosphate 20-10-10 TAN 10-5-5 Nitrite Control 40-20-20 0.21 4.43 6.685 8.625 14 0.115 3.97 5.81 8.215 21 0.24 3.92 5.68 6.725 28 0.36 3.85 5.41 5.73 Day/ Treatments 20-10-10 40-20-20 115 121.8 150.6 188 113.6 118.8 136.6 178.4 14 99.6 100.5 121.6 175.6 21 81.7 100.4 110.8 174.4 28 71.9 95.3 105.8 171.5 34.4 40.2 41 60 Potassium 10-5-5 Magnesium Control 33.8 39.2 39 59 14 33 38.8 38 58.7 21 32.5 38 37.6 58 28 32.1 37.3 37.4 57 Appendix 4: Weight and length of shrimp in Experiment Trt Initial 1st molting 2nd molting Molting Control W (g) L (cm) W (g) L (cm) interval 3rd molting Molting Molting W (g) L (cm) interval W (g) L (cm) interval (day) (day) (day) 5.3 9.3 6.1 9.4 5.3 9.5 6.2 10 6.8 10.3 12 5.1 9.2 5.5 9.4 9.5 10 5.4 9.5 5.9 9.6 6.2 9.6 15 5.2 5.5 9.1 6.8 10 16 7.4 10.1 13 4.8 7.4 4.9 7.9 5.3 11 5.8 8.2 10 5.1 8.3 5.2 8.3 5.6 8.5 6.1 8.8 10 5.1 8.7 6.3 9.4 10 5.5 9.6 5.6 9.6 6.2 9.8 10 11 4.5 7.5 4.6 7.5 7.9 5.7 12 12 4.3 7.6 3.9 7.4 13 4.4 7.6 4.2 4.7 8.3 5.3 8.5 11 14 4.3 7.5 4.5 7.6 4 7.4 3.9 7.3 4.3 7.6 4.6 8.2 4.6 8.2 4.9 8.4 10 4.9 8.8 5.3 4 7.4 10-5-5 Trt Initial 1st molting 2nd molting 3rd molting 4.2 7.5 4.3 7.7 4.8 7.9 10 7.6 7.8 4.3 8 8.2 12 5.3 4.9 8.4 8 4.3 7.6 4.4 7.5 4.3 7.7 10 7.8 4.2 7.7 4.6 7.8 5.1 10 11 4.2 8.3 4.5 15 12 4.9 8.2 4.7 8.1 13 7.9 7.9 4.6 13 14 4.5 8.2 4.7 8.1 8.2 15 7.4 5.8 9.1 6.4 9.7 13 6.7 10 11 4.6 8.2 5.7 9.7 6.3 10.1 12 6.6 10.5 10 4.9 8.8 8.6 5.6 9.3 11 4 7.4 5.4 9.2 4.2 7.5 4.7 8.8 5.1 5.4 9.2 7.6 4.4 9.5 12 7.6 4.2 8.3 4.8 8.6 11 5.1 11 4.3 7.6 5.7 9.5 6.2 9.7 12 7.5 5.9 9.6 12 6.4 10.2 11 6.8 10.6 11 10 7.8 6.9 20 11 4.2 8.3 4.9 15 20-10-10 Trt Initial 1st molting 2nd molting 3rd molting 12 4.9 8.2 4.8 8.6 5.6 9.1 21 13 7.9 8.1 5.7 8.6 10 14 4.5 8.2 4.5 7.5 4.5 10 3.9 7.6 4.4 10 3.9 7.9 5.2 11 4.4 7.6 4.6 7.7 13 4.3 7.7 4.7 7.8 11 4.9 5.2 8.4 5.3 8.4 6.2 8.8 4.6 8.1 4.7 8.2 5.2 7.8 4.9 8.1 18 4.5 8.3 4.6 10 4.5 8.3 4.6 8.3 11 3.9 7.8 4.5 12 4.9 8.2 13 4.6 14 4.1 17 40-20-20 7.5 5 8.3 11 10 6.7 9.1 10 8.5 10 5.7 8.7 10 5.3 8.3 11 12 8.4 8.2 11 5.9 8.6 6.2 8.6 6.4 8.9 8.3 4.8 8.4 5.2 8.6 12 8.1 4.5 8.3 8.4 10 5.5 8.8 10 1st molting 2nd molting interval interval WG WG LG Final W Final L Control WG1 LG1 LG 2 0.6 0.3 1.5 0.8 6.8 10.3 0.5 0.1 0.9 0.3 9.5 0.3 0.8 0.1 6.2 9.6 0.6 0.1 1.9 7.4 10.1 0.4 0.1 0.5 0.2 0.8 5.8 8.2 0.4 0.2 0.5 0.3 0.5 6.1 8.8 10 0.6 0.2 0.7 0.2 6.2 9.8 11 0.4 0.4 0.7 0.1 1.2 0.5 5.7 0.5 0.3 0.6 0.2 0.9 0.9 5.3 8.5 0.4 0.3 0.3 0.2 4.3 7.6 0.3 0.2 0.3 0.2 4.9 8.4 0.5 0.2 0.6 0.4 4.8 7.9 0.3 0.2 0.7 0.2 0.6 8.2 10 0.4 0.1 0.5 0.2 1.1 0.2 5.1 13 0.6 0.1 0.6 0.1 4.6 14 0.3 0.1 0.5 8.2 0.6 0.6 0.3 0.3 2.7 2.6 6.7 10 0.6 0.4 0.3 0.4 2.3 6.6 10.5 12 13 14 10-5-5 20-10-10 0.6 0.7 1.4 0.4 0.2 0.6 0.6 0.3 0.5 0.5 0.6 12 0.8 13 9.2 0.2 5.4 0.5 1.8 0.3 0.2 1.2 1.7 5.4 9.2 0.3 0.4 1.1 1.4 5.1 0.4 0.4 2.8 3.1 6.8 10.6 0.5 0.7 0.9 5.6 9.1 0.7 0.5 1.7 0.7 5.7 8.6 0.5 0.5 0.8 8.3 0.4 0.3 0.2 0.2 0.6 0.3 4.9 0.9 0.4 0.5 0.3 1.5 0.7 6.7 9.1 0.5 0.3 0.5 0.2 1.1 0.6 5.7 8.7 0.4 0.2 1.3 0.5 5.3 8.3 10 0.4 0.1 0.5 0.1 8.4 11 0.5 0.2 1.1 0.4 8.2 12 0.3 1.5 0.7 6.4 8.9 13 0.4 0.2 0.6 0.3 5.2 8.6 14 0.5 0.1 1.4 0.7 5.5 8.8 40-20-20 0.5 0.2 0.5 0.3 0.3 0.4 DWG DLG SGR SGR (g/day) Control (cm/day) (%/day) (%cm/day) Days 20 0.075 0.04 1.25 0.40 17 0.052941 0.017647 0.96 0.19 24 0.033333 0.004167 0.58 0.04 29 0.065517 0.034483 1.02 0.36 23 0.043478 0.034783 0.82 0.45 22 0.045455 0.022727 0.81 0.27 10 12 0.058333 0.016667 1.00 0.17 11 21 0.057143 0.02381 1.13 0.31 12 13 21 0.042857 0.042857 0.89 0.53 11 0.027273 0.018182 0.66 0.24 11 0.027273 0.018182 0.57 0.22 12 0.05 0.033333 1.11 22 0.045455 0.027273 1.01 0.35 8 10 26 0.042308 0.007692 0.93 0.10 11 15 10-5-5 12 13 17 0.035294 0.005882 0.82 0.07 14 22 0.022727 0.48 0.00 32 0.084375 0.08125 1.61 0.94 30 0.066667 0.076667 1.20 0.82 12 0.175 0.225 3.75 2.72 18 0.066667 0.094444 1.40 1.14 20 23 0.047826 0.06087 1.06 0.74 17 34 0.082353 0.091176 1.56 1.02 10 20 11 15 12 23 0.030435 0.03913 0.58 0.45 13 14 0.121429 0.05 2.53 0.61 14 17 DWG DLG SGR SGR (g/day) (cm/day) (%/day) (%cm/day) 0.038462 0.030769 0.86 0.39 20-10-10 Days 40-20-20 26 10 11 22 20 0.03 0.015 0.65 0.19 27 0.055556 0.025926 0.94 0.30 29 0.037931 0.02069 0.74 0.25 29 0.044828 0.017241 0.97 0.21 10 21 0.02381 0.004762 0.50 0.06 11 18 0.061111 0.022222 1.38 0.28 12 26 0.057692 0.026923 1.03 0.32 13 19 0.031579 0.015789 0.65 0.19 14 28 0.05 0.025 1.05 0.30 ... COLLEGE OF AQUACULTURE AND FISHERIES EFFECTS OF MAGNESIUM-PHOSPHORUS-POTASSIUM CONTAINING IN WATER ON MOLTING, GROWTH AND SURVIVAL RATE OF THE WHITE SHRIMP (Litopenaeus vannamei) JUVENILES, REARED IN. .. remains until the next molting cycle Duration of the molting cycle depends on the species and age of the shrimp Molting frequency on white shrimp decreased along with increasing the size of shrimp. .. observation of feeding activity of shrimp Salinity water was 2‰ Determination of molting intervals of shrimp: Molting of shrimp were recorded daily at 7~8:00 AM through the old shell in the net case Shrimp