2--Bioslurry-for-Fishpond-final-report.pdf

INDEPENDENT CONSULTANT

AQUACULTURAL DEPARTMENT FACULTY OF ANIMAL AND AQUACULTURAL SCIENCES

HANOI UNIVERSITY OF AGRICULTURE

FINAL REPORT ON RESEARCH IMPLEMENTATION

Utilization of bioslurry for comercial fishpond

PROJECT : BIOGAS PROGRAM FOR THE ANIMAL HUSBANDRY SECTOR IN VIETNAM 2007 - 2011

INVESTOR : LIVESTOCK PRODUCTION DEPARTMENT MINISTRY FOR AGRICULTURE AND RURAL DEVELOPMENT

CONSULTANT : INDEPENDENT CONSULTANT TEAM

AQUACULTURAL DEPARTMENT FACULTY OF ANIMAL AND AQUACULTURAL SCIENCES HANOI UNIVERSITY OF AGRICULTURE

HANOI, 2011

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INFORMATION OF PROJECT

1. Objectives: To estimate the method of using bioslurry from Biologic Gas Project and the effects of that to grow-out pond.

2. Organization in charge: Biologic Gas Project to Animal Science Sector in period of 2007 - 2012

3. Implementation Organization: Independent consulting Team of Aquaculture Department, Faculty of Animal Science and Aquaculture, Ha Noi University of Agriculture.

4. Co-operation team:

5. Expenditure in total: 394,1 Million Vietnam Dong

6. Duration: From January, 2011 to September, 2011.

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PARTICIPANTS

I. Head of consultant team Eng. Nguyen Van Tuyen, Aquacultural Department, Faculty of Animal and Aquacultural Sciences, Hanoi University of Agriculture. II. Team members

No. Full name Degree Office

1 Ms. Pham Thi Lam Hong Master Aquacultural Department, Faculty of Animal and Aquacultural Sciences, Hanoi University of Agriculture

2 Ms. Tran Anh Tuyet Engineer

3 Mr. Trinh Dinh Khuyen Master

4 Mr. Vo Quy Hoan Master

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CONTENTS

INFORMATION OF PROJECT ..................................................................................... i

PARTICIPANTS ............................................................................................................ ii

CONTENTS .................................................................................................................. iii

ABBREVIATIONS AND ACRONYMS ...................................................................... vi

LIST OF TABLES ........................................................................................................ vii

LIST OF TABLES ........................................................................................................ vii

LIST OF FIGURES ..................................................................................................... viii

SUMMARY ..................................................................................................................... x

BACKGROUND ............................................................................................................. 1

CHAPTER I: DOCUMENT OVERVIEW, OBJECTIVE, CONTENT AND METHODOLOGY .......................................................................................................... 2 I. DOCUMENT OVERVIEW ......................................................................................... 2 1.1 Biogas technology ..................................................................................................... 2

1.2 Bioslurry .................................................................................................................... 2

1.3 Quality of bioslurry ................................................................................................... 3

1.4. Utilization of bioslurry in agriculture and fish culture ............................................. 4

1.5 Biological characteristics of some fish used in the research ..................................... 7

2.1. Objective and Approach ......................................................................................... 14

2.2. Approach ................................................................................................................ 14

2.3. Research content ..................................................................................................... 15

2.4. Research methodology ........................................................................................... 16

CHAPTER II: RESULTS AND DISCUSSION............................................................ 21 I. SUBJECT 1: USING BIOSLURRY FOR COMMERCIAL FISHPOND ................ 21 1. Growth rate ................................................................................................................ 21

1.1. Growth rate of silver cap ........................................................................................ 21

1.2. Growth rate of Grass carp ....................................................................................... 24

1.3. Growth rate of Indian carp ..................................................................................... 26

1.4. Growth rate of Common carp ................................................................................. 29

1.5. Growth rate of Black carp ...................................................................................... 32

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1.7. Growth rate of Tilapia ............................................................................................ 37

2. Survival rate ............................................................................................................... 40

3. Food conversion ratio ................................................................................................ 42

II. SUBJECT 2: CULTURE ENVIRONMENT AND FISH HEALTH ....................... 45 1. Monitoring results of environmental parameters before fish culturing ..................... 45 2. Fluctuation of hydration and physical hydrology in culturing environment .................... 45 2.1. Temperature fluctuation ......................................................................................... 45

2.2. Fluctuation of Dissolved oxygen (DO) .................................................................. 47

2.3. pH fluctuation ......................................................................................................... 48

2.4. NH4+ fluctuation ...................................................................................................... 50

2.5. NH3 fluctuation ....................................................................................................... 51

2.6. Nitrate (NO3) fluctuation ....................................................................................... 52

2.7. Nitrite (NO2) fluctuation ....................................................................................... 53

2.8. Turbidity fluctuation ............................................................................................... 54

3. Hydration fluctuation ................................................................................................. 56 3.1. Phytoplankton changes ........................................................................................... 56

3.2. Fluctuations of phytoplankton ............................................................................... 59

3. Results on fish health monitoring .............................................................................. 61 3.1. Prevention ............................................................................................................... 61

III. SUBJECT 3 EVALUATION OF COMPREHENSIVE EFFICIENCY AND ECONOMY WHEN USING BIOSLURRY FOR COMMERCIAL FISH POND ...... 64 1. Evaluating economic efficiency ................................................................................ 64

CHAPTER III. CONCLUSION AND RECOMMENDATION ................................... 66 1. Conclusion ................................................................................................................. 66 1.1. Growth of fish ......................................................................................................... 66

1.2. Survival rate ............................................................................................................ 66

1.3. Feed conversion ratio (FCR) .................................................................................. 66

1.4. Fluctuation of environmental factors ...................................................................... 66

1.5. Disease .................................................................................................................... 67

1.6. Assess the comprehensively effectiveness of the use of bioslurry in commercial

fish ponds ....................................................................................................................... 68

2. Recommendation ....................................................................................................... 68

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CHAPTER IV: REFERENCES .................................................................................... 69 I. Vietnamese documents .................................................................................................. 69 II. English documents ....................................................................................................... 69

CHAPTER V: APPENDIX ........................................................................................... 71 1. Weight ....................................................................................................................... 71 2. The number of dead fish ............................................................................................ 73 3. Feed (kg) .................................................................................................................... 75 4. Temperature (C) ....................................................................................................... 75 5. DO (mg/L) ................................................................................................................. 76 6. pH .............................................................................................................................. 77 7. NH4+, NH3 (mg/L) ..................................................................................................... 78 7. NO2, NO3 (mg/L) ....................................................................................................... 79 8. Turbidity (cm) ............................................................................................................ 80 9. Some pictures on research ......................................................................................... 81

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ABBREVIATIONS AND ACRONYMS

A : Afternoon

FCR : Food Conversion Ratio

GIFT : Genetic Improvement of Farmed Tilapia

M : Morning

P : Pond

T : Treatment

VN : Viet Nam Dong

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LIST OF TABLES

Table 1: Macro nutrients in bioslurry and fresh pig manure ...................................... 3

Table 2. Household participated in research ............................................................ 15

Table 3. Arrange experiments .................................................................................. 17

Table 4. Growth rate of Vietnam Silver cap ............................................................. 21

Table 5. Growth rate of grass carp ........................................................................... 24

Table 6. Growth rate of Indian carp ......................................................................... 26

Table 7. Growth rate of Common carp ..................................................................... 29

Table 8. Growth rate of Black carp .......................................................................... 32

Table 9. Growth rate results of Bighead carp ........................................................... 35

Table 10. Growth rate results of Tilapia ................................................................... 37

Table 11. Survival rate among fish of all experiment (%) ....................................... 40

Table 12. FCR in all experiment treatments during farming time ........................... 43

Table 13. Environment parameters in all experimental before fish culturing .......... 45

Table 14. The parasite check before stocking .......................................................... 62

Table 15. Periodically monitoring on parasitic infected ratio .................................. 62

Table 16. Economic accounting (million VN) ...................................................... 64

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LIST OF FIGURES

Figure 1. Silver carp (Hypophthalmichthys) .............................................................. 7

Figure 2. Bighead carp (Aristicthys nobilis) ............................................................... 8

Figure 3. Common Carp (Cyprinus carpio) ............................................................... 9

Figure 4. Grass carp (Ctenopharyngodon idellus) ..................................................... 9

Figure 5. Black carp (Mylopharyngodon piceus) ..................................................... 10

Figure 6. Nile Tilapia Oreochromis niloticus ........................................................... 11

Figure 7. Indian carp (Labeo rohita) ........................................................................ 13

Figure 9. Absolute growth rates of the silver carps .................................................. 22

Figure 10. Growth rates of the Silver carps in checking times ................................ 23

Figure 11. Absolute growth rates of the grass carps ................................................ 24

Figure 12. Growth rates of the grass carp in checking times ................................... 25

Figure 13. Absolute growth rates of the Indian carp ................................................ 27

Figure 14. Growth rate of Indian carp in all experimental treatments ..................... 28

Figure 15. Growth rate of Common carp in all experimental .................................. 30

Figure 16. Growth rates of the Common carp in all experimental treatments ......... 31

Figure 17. Absolute growth rates of the Black carp ................................................. 33

Figure 18. Growth rates of the Black carp in all experimental treatments ............... 34

Figure 19. Absolute growth rates of the Bighead carp ............................................. 36

Figure 20. Growth rates of the Bighead carp in all checking times ......................... 36

Figure 21. Absolute growth rates of the Talapia ...................................................... 38

Figure 22. Growth rates of the Talapia in all checking times .................................. 39

Figure 23. Average survival in all experimental ...................................................... 41

Figure 24. Survivap raion of all fish furing farming time ........................................ 42

Figure 25. FCR ......................................................................................................... 44

Figure 26. Daily temparature fluctuation ................................................................. 46

Figure 27. DO fluctuation in morning ...................................................................... 47

Figure 28. DO fluctuation in afternoon .................................................................... 47

Figure 29. pH fluctuation in morning ....................................................................... 49

Figure 30. pH fluctuation in afternoon .................................................................... 49

Figure 31. Timely NH4+ variation ............................................................................ 50

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Figure 32. NH3 variation in all experiment ............................................................... 51

Figure 33. NO3 variation in all experimental treatments ........................................ 52

Figure 34. NO2 fluctuation in all experiment .......................................................... 54

Figure 35. Turbidity of all experimental fishponds .................................................. 55

Figure 36. Ratio of algae species in experiments ..................................................... 56

Figure 37. Fluctuation of Phytoplankton amount during rearing time ..................... 57

Figure 38. Percentage of species of phytoplankton in the treatments ...................... 59

Figure 39. Fluctuations of zooplankton over the culture period .............................. 60

Figure 40. experiment pond ...................................................................................... 81

Figure 41. weighting fish .......................................................................................... 81

Figure 42. pellet feed and Fish Health production ................................................... 82

Figure 43. Test Sera .................................................................................................. 82

Figure 44. Disease in Grass Carp by Aeromonnas spp ............................................ 83

Figure 45. Disease in Black carp by Aeromonnas spp ............................................. 83

Figure 46. Probiotic ANOVA NB - 25 ..................................................................... 84

Figure 47. Benkocid ................................................................................................. 84

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SUMMARY

Overview

The development of Animal Science Sector has opened the establishment of Biologic Gas Technology in order to deal with waste of Animal Science Sector. Residues from process of Biologic Gas producing include bioslurry, waste matter and scum. Those brings certain advantages to Aquaculture such as reducing risk of disease infecting; increasing growing rate of fish caused by bioslurry containing nutrient which enrich aquatic organism system. In order to estimate the effects of using bioslurry to grow-out pond, we carried out experiment named Utilization of bioslurry for comercial fishpond

Objective To study method(s) using bioslurry for commercial fish pond and benefits of

the practice. Define method(s) using bioslurry for commercial fish pond (eg. Diet of

bioslurry and pellets; substitution rate of bioslurry for organic manure; substitution rate of bioslurry for chemical fertilizer; what attention should be paid when using bioslurry for fish farming); Calculate economical, environment and safe product benefits; Develop manual on using bioslurry for commercial fishpond.

Method Four formulations was used with tow replicates for each in 8 ponds

(1000m2/pond). Experiment did from January to June, 2011 in nh Bng, T Sn, Bc Ninh.

Results The using of bioslurry shows good influence to growth of fish. That using with

method of mixing and distributing present better effects in comparison with that of using no bioslurry. Especially, Grass Carp and Black Carp which prefer living in clean water, show significant growth. The survival rate was show being lowest at treatment with using pig manure of 85,83%. The highest rate is of 89,29% in treatment with mixture if bioslurry and pellets. Common Carp shows highest survival rate of 94,15% and lowest one is in Grass Carp being 78,61%.

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Feed Converting Rate shows considerable increase during experiment period, that is lowest at 1.42 in method of mixing bioslurry with pellets and highest at 1.55 in control.

In general, water and hydration of the ponds in all treatments are suitable for the development of fish.

Phytoplankton in pond using bioslurry is abundant, in which 222 species of algaes were defined and refered to 5 main species named Euglenophyta, Chlorophyta, Cyanophyta, Bacillariophyta and Pyrrophyta. Some dominate in the pond like Phacus, Trachelomonas, Scenedesmus, Pediastrum, Closterium, Oscillatoria, Melosira. Zooplankton was also isolated with 26 species in 3 groups named Cladocera with 8 species holding 30,76%, Copepoda and Rotatoria with 9 species for each occupying 34,62 %.

We were monitoring epidemic diseases in fishes. We saw epidemic diseases happened in Grass carp and Black carp. Epidemic disease happened strongly in the trial adding pig manure. Thus, when use water discharge from biogas project effect well to speed growth up, rate live kind of fishes in the trade pond. Special, there are two kind of fishes like clear water environment are Grass carp and Black carp. Beside it effect to speed growth up, it reduce coefficient of food (0,13) compare non-use water discharge from biogas project. So, to produce 1 kg of fish if the water discharged from the use of biogas will save 0.12 Kg compared to the non-food use of discharge. Otherwise, use water discharge to be limited as well as disease and make clean products. Finally, when using effluents from biogas projects, bringing economic efficiency than non-use of water discharged from 3.18 to 3.25 million on an area of 1000m2 in the 6 months of culture.

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BACKGROUND

Biogas technology was of interest from the middle of the 19th century and

realy attracted the attention of scientists since 1973 due to the importance of biogas

and the benefits of biogas as source not only non-polluting but also clean energy to

the environment (FAO, 1992).

Today biogas has gain more interested in many countries around the world

and is considered a kind of efficient renewable energies for rural areas. China, India

and Israel are the countries that have extensive experiences in exploitation and

utilization of bioslurry. Many international organizations such as ESCAP, FAO,

WHO, UNIDO, UNEP has been early interested in assessment, development and

support for studies biogas to deal with multi-dimensional and comprehensive

problems of the world in terms of eco- society, food, industry, medicine and

environment (FAO, 1992).

In Vietnam, the use of organic manure for fish-ponds has its long history.

However, this practice not only cause fish diseases as manure bring many harmful

bacteria but also consume dissolved oxygen in water, resulting in the reduction of

dissolved oxygen and head-floating increase. Along with the rapid development of

biogas digester construction, farmers start to use bioslurry to replace the use of fresh

manure. In some provinces, a number of demonstration pilots using bioslurry for

fish pond. Even though positive results achieved from demonstration pilots but still

lack of concrete formula for the substitution of bioslurry for chemical fertilizer or

animal fresh manure nor the calculation for benefits of the practice in terms of

economy, environment and safe product.

Therefore, the study "Utilization of bioslurry for commercial fishpond" is

needed to give people guidance, specific processes and issues that need to be paid

attention during the utilization of bioslurry for commercial fishponds.

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CHAPTER I: DOCUMENT OVERVIEW,

OBJECTIVE, CONTENT AND METHODOLOGY

I. DOCUMENT OVERVIEW

1.1 Biogas technology

Biogas technology was of interest from the middle of the 19th century and realy attracted the attention of scientists since 1973 due to the importance of biogas and the benefits of biogas as source not only non-polluting but also clean energy to the environment (FAO, 1992). Today biogas has gain more interested in many countries around the world and is considered a kind of efficient renewable energies for rural areas. China, India and Israel are the countries that have extensive experiences in exploitation and utilization of bioslurry. Many international organizations such as ESCAP, FAO, WHO, UNIDO, UNEP has been early interested in assessment, development and support for studies biogas to deal with multi-dimensional and comprehensive problems of the world in terms of eco- society, food, industry, medicine and environment (FAO, 1992). In Vietnam, the Centre for New and Renewable Energy under the Institute of Energy has researched on using local construction materials and other materials to build biogas plants. Some typical plants were constructed in different geographical areas while the development programs gained the concern of the State (FAO, 1992). The Project Biogas Program for the Animal Husbandry Sector in Vietnam (the Project) has been implemented for 8 years by the Department of Livestock Production (DLP) of the Ministry of Agriculture and Rural Development (MARD) in cooperation with the Netherlands Development Organization (SNV). The Project has collaborated with professional bodies/organizations to perform a number of studies using bioslurry for pig production and cultivation, achieved some initial results to serve as a basis for guidance to project officers and farmers to implement in reality. However, the project has not conducted any studies on the use of bioslurry for fishpond.

1.2 Bioslurry

Bioslurry has three types of liquid bioslurry, residue and scum. Liquid bioslurry is in liquid form and stored in boislurry pit or compenstation tank that connect to the digester (Biogas Program for the Animal Husbandry Sector in Vietnam, 2008). Researches on bioslurry have been implemented in many countries

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in the world to maximize the utilization of this patent fertilizer in many sectors and purposes like fertilizers for crops, use as additional feed for pig, use for mushroom cultivation and aquacultural production.

1.3 Quality of bioslurry

The quality of bioslurry that was studied by the Project includes the nutritional content and safety levels of bioslurry. Nutritional content of bioslurry includes poly nutritional elements and pH. Analysis results show that bioslurry is slightly acid or neutral pH and can be used to irrigate all crops. Bioslurry is of high protein content and total potassium, rather high total phosphorus, mainly in the form of easy to use for crops such as N-NO3, N-NH4, effective phosphorus and potassium. When compared with regulations on standard hydroponic solution, bioslurry has total nitrogen of 2.5 to 4.3 times (mean 3.4 times) higher, total phosphorus of 0, 38 to 1.14 times higher, total potassium of 2.02 to 2.54 times higher than that of standard hydroponic solution. Compared to the maximum limit in hydroponic solution, bioslurry has much higher of trace elements such as Cu is of 1.8 to 10.9 times higher, Zn is of 2.8 to 10.7 times higher, Mo is of 3.1 to 4.4 times higher while a number of other elements such as Mn, Mg, Fe has equal or slightly higher value. Some elements have lower concentrations such as Ca, Bo. When comparing the levels of macro nutrients (N, P; K) between the bioslurry and fresh manure, it was found that concentrations of macro nutrients in bioslurry are lower than those in fresh manure as shown in Table 1:

Parameter Bioslurry Fresh pig manure Total N (%) 0.06 - 0.07 0.7

Total P2O5 (%) 0.016 - 0.018 1.42

Total K2O (%) 0.107 - 0.129 0.54

(Cao K Sn and partners, 2008)

Table 1: Macro nutrients in bioslurry and fresh pig manure Even though bioslurry has the lower concentration of macro nutrients but the nutrients are mainly in the form of inorganic minerals thus plants and phytoplankton can use immediately. In pig manure, nutrients are partly in the form of inorganic minerals, while the other are in the form of organic compounds thus plants and phytoplankton can not be used immediately, instead it need to be under degradable process to be in the form of inorganic minerals. The utilization of bioslurry is good to the growth of phytoplankton, then good to the growth of bottom species, thus

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positively effects fishes, especialy for the filter feeders (Silver carp, Bighead) and benthic species (Common carp, Indian carp)

Safety of bioslurry: according to Le Thi Xuan Thu (2008), the reason why the concentration of Cadmium, lead, arsenic in bioslurry after biogas treatment are higher than those of allowed threshold can be caused of the infiltrate from food or from drinking water. The process of biogas decomposition itself does not create heavy metals, but change the dynamics of the heavy metals from bio-residue or scum to new forms in bioslurry. It is pretty simple to handle this issue, if would like these metals is deposited in residue or scum, just increase the pH of bioslurry. Bio-residue and scum can be produced organic fertilizer after being composted with straw and/or leaves... that can be safety used for crops. If would like to use bioslurry to irrigate crops, just diluted to concentrations of heavy metals under the suggested threshold.

Microbial safety: The density of microorganisms in the cow manure is 1.27 x 108 CFU/g, in pig manure is 1.39 x108 CFU/g, in a mixture of cow and pig manure is 2.52 x 108 CFU/g that suit to normal distribution of microorganisms in general manure in Vietnam. In bioslurry it is not found epidemic microorganisms such as cholera, typhoid and almost no worm egg density. The degradation of manure in the digester reduces the density of microorganisms in bioslurry to an average of 63.5 times (for cow), 24.0 times (for pig) and 89.4 times (for a mixture of cow manure + pig manure).

According to Cao Ky Son et al 2008, the density of microorganisms in bioslurry is under the permission thredhold, in average of 2 x 106 CFU/ml (bioslurry of the cow dung), 5.79 x 106 CFU/ml (bioslurry of pig dung) and 2.82 x106 CFU/ml (bioslurry of mixture of cow dung and pig dung). It is not found the disease - causing microorganisms, only found few helminth eggs of 1.7 to 3.7 eggs/25 ml they may be introduced from outside into the bioslurry or unexplained sources. Thus bioslurry is safety due to having no disease-causing microorganisms nor insignificant worm eggs, are eligible to irrigate crops.

1.4. Utilization of bioslurry in agriculture and fish culture

Today people care more about construction and utilization of biogas system. Many studies have shown the importance of bioslurry and the utilization of bioslurry become popular in countries like China, India and other countries in South Asia. Bioslurry can be used as a potent fertilizer for crops, as fertilizer for fish production and this system remarkably contributes in pollution reduction. In addition, bioslurry after anaerobic digestion of waste from pig, cattle or poultry can be safely used as additional feed for animal as they can provide protein (2.94% N according to dry matter), multi-minerals and vitamins.

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In 2004, Giang and Len conducted a study on impact of bio-slurry to the development and food transformation in hybrid pig F2. They concluded that mixture of 1 - 2 litters of bio-slurry digested from pig excreta and 1kg mixed food can help increase the efficiency of food transformation and weight of pig. The result shows that when blending bio-slurry with mixed food, there is no symptom of respiration or digestion illness in pigs. However, not many studies focus on methods to process bio-slurry before feeding pig as well as how to feed the pig to get the highest efficiency. Using bioslurry in aquaculture has been known in many countries with a tradition and high technology in fisheries science, such as China, Israel, the Philippines. From the years 1977 - 1978, in Middle East and Israel there have been many trials and studies using untreated animal dung as cow manure as food for fish in the pond . Many experiments were conducted in ponds having polyculture of Carp, Tilapia and White Silver carp. The experiment compared the growth rates of fishes in the ponds when using pellets, fresh cow dung and composted cow dung. The results showed that the growth rate of Tilapia did not differ between treatments. Dissolved oxygen in the ponds varied from 1 to 8 mg/L and in average maintained at 3 mg/L in 80% of the raising time. Primary productivity has been studied to assess the impact of organic matter in ponds on fish yield. Rates of photosynthesis in ponds receiving bioslurry are higher in comparison with those in the ponds using chemical fertilizers. Ponds with bioslurry have rate of zooplankton higher than those in ponds without bioslurry. Results of experiments in three seasons shows using bioslurry for fish ponds can save 50% pellets, eg economically meaning. Degani et al. (1982) conducted laboratory studies using a number of treatments and bioslurry with different diets for Tilapia. Results showed that bioslurry can replace 50% of food in fish farming but the different types of bioslurry, the different effect. Other study evaluating the effects of bioslurry in raising Tilapia showed a part of carbohydrate was replaced by the growth of algae that make balancing the ratio between the energy exchange with the protein in the diet. The results also indicate that bioslurry may play an important role to increase the amount of dissolved oxygen in the pond so help increase primary productivity and Chlorophyll A concentration. Experiment by Marchaim et al, (1983) in pond having carp showed levels of dissolved oxygen in the pond is higher than those in pond with regular fish feed. In China, since 1988s people used pig manure for fishponds to stimulate the growth of aquatic plants to create a natural food source in the ponds. According to Fang Xing and Xu Yiz Hong (1988), the Chinese sprayed liquid bioslurry into the pond every 3 days with a volume of 400 kg/666 m2. This practice showed that the

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utilization of bioslurry for fishpond have many benefits. First, bioslurry contains many nutrients, macro elements and micronutrients that stimulate the growth of phytoplankton and zooplankton in the pond. The aquatic organisms are direct or indirect feed that help increase fish yield. In southern China, raising fish in pond is very common practice. Normally, fish is fed with wheat bran, but recently people use bioslurry as additional feed to increase fish productivity while reduce production costs (Center for Biogas Technology of China, 1982). As bioslurry is the product of the the degredation of organic matters that have been fermented completely, dissolved oxygen in water will not be consumed thus not badly impact water quality. Bislurry has brownish gray color so it absorbs heat from the sunlight better, then the temperature of water ponds increased thus positive impact growth rate of fish. During anaerobic fermentation in the digester, bactericidal and eggs of the parasite causing disease in the fresh dung are killed, so fish in the pond using bioslurry are less infected with diseases. pH value of water of pond using bioslurry is neutral so suitable for the growth of fish. In Vietnam, the use of organic manure for fish-ponds has its long history. However, this practice not only cause fish diseases as manure bring many harmful bacteria but also consume dissolved oxygen in water, resulting in the reduction of dissolved oxygen and head-floating increase. Along with the rapid development of biogas digester construction, farmers start to use bioslurry to replace the use of fresh manure. In some provinces, a number of demonstration pilots using bioslurry for fish pond. Even though positive results achieved from demonstration pilots but still lack of concrete formula for the substitution of bioslurry for chemical fertilizer or animal fresh manure nor the calculation for benefits of the practice in terms of economy, environment and safe product. According to Le Thi Xuan Thu (2008), so far in Vietnam, there are very few studies on bioslurry or nutrient content, toxins and benefits as fertilizer for crops of bioslurry. During the years of 2007 - 2008, the Biogas Program for the Animal Husbandry Sector in Vietnam (the Project) in collaboration with the Research Centre for Nutrition and Fertilizer for plants (National Institute of Soils and Fertilizes) performed a review on the quality of bioslurry based upon results from an investigation and systematic analysis of a wide range of different indicators. The review was carried out in Soc Son district, Hanoi at 9 households having biogas plants that built and operated in accordance with the procedures of the Project. At each household, a slurry pit of 1m3 was built to connect with the compenstation tank. Feeding materials for the digester are cow dung, pig dung and mixture of cow dung and pig dung. Water used to dilute the dung is in accordance with the design and direction to ensures that the animal manure stay in the digester for 45 days.

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1.5 Biological characteristics of some fish used in the research

1.5.1 Vietnam silver carp (Hypophthalmichthys harmandi Sauvage, 1844)

Distribution: Previously, Vietnam white bighead is widely distributed in the Red River system, Thai Binh River, Ma River, and Lam River. This is the typical species of fish in the North of the country. Many documents show this species is detected in the South of Hainan-China. At present, due to the uncontrolled production of varieties of the species, the pure original species are not existed, especially the Vietnam white bighead.

Figure 1. Silver carp (Hypophthalmichthys)

Living behavior: Fish lives in the middle layer, agility, live in herds in rivers, lakes, ponds and fields. When grown in reproductive season fish migrate to the upstream of the river where the ecological conditions are suitable for breeding.

Eating behavior: Major foods of white bighead are phytoplankton and a few zooplankton and organic mulch residue. Growth: In natural conditions in the river, the fish grow rapidly: At 1 year old fish rearch 35.1 - 38cm, weigh 0.785 - 0.885 kg. At 2 years old fish rearch 43.3 - 43.5cm, weigh 1.404 - 1.532 kg. At 3 years old fish rearch 54.1 cm and weight 1.938 - 2.037 kg. In ponds, the growth rate depends on nutrient conditions and density of raising fish, usually after a year one fish reaches 0.3 to 0.5 kg.

1.5.2. Bighead carp (Aristicthys nobilis Rich)

Distribution: Bighead carp is one of the typical species of the fish fauna at the plains of China. At the begining, Bighead carp was naturally distributed Yangtze River and Ngoc River. In our country, Bighead carp is only distributed in Ky Cung River (Lang Son), but the quantity is very low. In 1958 the fish was imported from China and sucessfully carried out the artificial breeding in 1963. From that time the Bighead carp have been become widely farmed in many localities.

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Living behavior: Bighead carp mainly lives in middle layer of water and upper layer of water. They preferred to live in nutrient-rich waters, rich in dissolved oxygen and live in herds. The fish stop eating when dissolved oxygen levels below 1.1 mg/L and death when oxygen concentration is at 0.2 to 0.3 mg/L.

Figure 2. Bighead carp (Aristicthys nobilis)

Eating behavior: At the stages of fry and fingerlings, they eat mainly plankton, or artificial food such as rice bran, wheat, soybean flour. At the stage of maturation, the Bighead carp eat mainly plankton or little algae and also use fine feed. The strong nutrition of the fish is strong in spring, summer and the fall, but falling food in winter but never stop permanently.

Growth: The Bighead carp of 12 days old have 1.52 cm long and weighs 0.134g; 22-day-old one has 1.91cm long and weight 0.176g; 80 days old are 6 cm in length, weighs 63.3 g. The Bighead carp grow faster than the Silver carp. The maximum of length grow from year 1 to year 3 and then decline gradually. In terms of weight of the fish, it increase fast from year 2 to year 6, but the fastest in year 3. The growth of Bighead carp depends on the density of farming and nutrition. When farming density in ponds is low, the fish grow fast: after 1 year fish can weigh 1.0 - 1.5 kg; even 2.0 - 2.5 kg; the fish of two to three years weigh 4 - 6 kg. In the newly formed reservoir, where rich in natural food, the fish grow very fast. Thac Ba Lake (Yn Bi) fish of 1-year-old weigh 2.7 kg; 2-year-old fish weigh 5.218 kg. Cam Son Lake (Bac Giang) fish of 2-year-old weight 20 kg. The biggest Bighead carp was caught in the country is from Thac Ba Lake in 1976.

1.5.3 Common carp (Cyprinus carpio, Line 1758)

Distribution: Common carp is a species that widespread throughout the world. They are found in all types of freshwater. According to a survey by Tran Dinh Trong, Vietnam has seven different types of carp with variety of color. However, carp that are raised most popular is the white carp in the North. Currently, V1 common carp is the most preferred in Vietnam. V1 is selected by the Institute of Aquaculture. Carp V1 has many good characters as they collected good characters from the fish flakes from Hungary, Common Carp from Indonesia and the white carp in Vietnam.

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Figure 3. Common Carp (Cyprinus carpio)

Eating and growth: Fish of 3 to 4 day-old have length of 6 to 7.2 mm live at the upper water layer. Fish of 4 to 6 day old have length of 7.2 to 7.5 mm lives at the middle water layer. Their main feed is plankton. Fish of 80 to 10 days of age have length of 14.3 - 19 mm. Their siege began complete, having flakes, whiskers. Their feed are mainly small benthic. Fish of 20 - 28 days old have length of 19 to 28 mm, live mainly in the bottom. They mainly eat benthic food, organic mulch and a small residue of phytoplankton. When being adult, carp eat the main benthic mollusks, larvae, insects, worms ... In addition, they eat organic residue mulch, bulbs, vegetable seeds and artificial feed. Carp cultured in ponds normally reach weight of 0.7 to 1.0 kg/year. Extensive productivity in the improved culturing ponds in Europe is about 500 kg/ ha/year.

1.5.4 Grass carp (Ctenopharyngodon idellus)

Figure 4. Grass carp (Ctenopharyngodon idellus)

Distribution: Grass carp is a native Chinese freshwater fish with a broad distribution of water in Central Asia, the plains of China, Hainan Island, Amua River Basin, which borders the Soviet Union (former) with China. In Vietnam, P.cherey and Lemasson (1927) found grass carp in the Red River. Grass carp also naturally distributed in Ky Cung River (Lang Son). In 1958, grass carp were imported from China. In 1967 artificial breeding of grass carp was succesful, then the fish become the object of popular culture, especially for mountainous areas, and the object to cage culture in the north.

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Feed: 3 days after hatching fish reach the lenghth of about 7 mm. They started feeding rotifers, non-vertebrae larvae and inferior algae. Fish of 2 to 3 cm start feeding a little pre - plant, proportion of rotifers in the diet reduced, but the crustacean plankton accounted for main proportion in feed. Fish of 30 to 10 cm long can crush superior plants and they switch to feed aquatic plants. Natural food of grass carp is mainly mature superior plant (both aquatic and terrestrial), some insects and worms. Consumption of vegetation of huge grass carp is from 22.1 to 27.8% by weight of fish per day. On average, 40 kg of plant will gain 1 kg of fish. Grass carp feed well artificial feed. However, if the ingredients more starchy, more fatty fish and less growth of fish. Growth: Under culture conditions in Vietnam, when nursuring with density of 180 - 200 fry/m2 for 25 - 30 days, the fish can reach length of 3 - 3.1 cm and weight of 140 - 240mg. At stage of nursuring with density of 10 fry/m2, after two months of nursuring the fish can rearch length of 10 - 12 cm. In mature ponds, 1 year old fish can reach 1 kg and 2 year old fish can reach 2 - 4 kg. Where abundant of aquatic seed, 3 year old grass carp can reach 9 - 12kg/fish.

1.5.5 Black carp (Mylopharyngodon piceus)

Figure 5. Black carp (Mylopharyngodon piceus)

Distribution: In nature Black carp are distributed in China and North

Vietnam. In Vietnam the fish are distributed in the lower Red River, Thai Binh,

Ma, Lam Rivers.

Living character: Grass Carp are peaceful, prefer to clean water, live in

bottom. Their endurance to the fertility of water is less than grass carp.

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Feed: Fry feed mainly zooplankton, while adults feed primarily benthic as

snails, mussels... When feeding, fish use teeth to crush the shells and extract the

meat. In farming ponds and lakes, the Black carp can feed bran, bran circuit, cake,

industria food. Currently Black carp are mostly polycultured with a very low rate in

ponds (1 - 2 fry/sao of pond). Recently appeared monoculture and polyculture of

Black carp in ponds with high rates using both snail and industrial food (Kim Van

Van et al, 2009).

Growth: Black carp is a big size commercial fish with rapid growth rate,

particularly in year 2 and year 4 fish grow quickly. Standard commercial Black carp

from 2.5 kg and above.

1.5.6 Nile Tilapia Oreochromis niloticus

In 1974, Research Institute for Aquaculture No. I imported Nile tilapia with

types of GIFT, Egyptians and Thai from the Philippines. Studies show that GIFT

type , grow faster than types of Viet and Egyptians (Nguyen Cong Dan, 2006).

Figure 6. Nile Tilapia Oreochromis niloticus

Feed: Tilapia are omnivores plant preferred fish. According Chervinski (1982), their feed change at stages of development and culture environment. Their feed are mainly algae, a part of vascular plant and organic humus. In the fry stage (from lavae to fingerlings) their feed is zooplankton. From the fingerlings stage to the mature stage they feed mainly humus and organic residues of phytoplankton. Nile Tilapia can digest green algae, which cannot be digested by some other species. Nile tilapia feed the additional feed such as rice bran, cornmeal and other agricultural residue. Development and growth: The growth and development of tilapia of all stages is not entirely like other fish, and can be divided into 14 stages.

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After hatching 3 to 5 days, tilapia have length of 6.5 to 10 mm, the ball full of air, the fish are able to swmim out, on the surface water layer, and able to catch prey. After hatching 5 to 7 days, tilapia have length of 10 - 10.5 mm, swim to the bottom to feed small Chironomus. After hatching 7 - 9 days, the fish have length of 10.5 - 11mm, live outside their mother fish mouth and able to catch prey. After hatching 9 - 10 days, the fish have length of 11 - 15mm, out of ovule, have all fins, live completely outside. After 20 days, tilapia have length of 17.5mm, have all fins, stable body. Tilapia feed mainly algae, plankton, benthic organic residues and humus. Speed of growth depends on the condition of culture and feed. Nile tilapia grow faster and larger than Black tilapia. Black Tilapia grow fast month 3 and 4 while Nile tilapia grow rapidly from month 5 and 6. Male grow faster than female, especially after sexual maturity. Nile Tilapia GIFT type can reach a weight of an average of 600 - 700g per fish, after 5 to 6 months farming (Trn Vn Tr, 2007). The heat threshold: According to Chervinski (1982), tilapia can stand up with temperatures of 5C to 40C. The growth of Tilapia decrease in temperatures below 20C. The fish stop feeding when temperatures below 15C. Most species of Tilapia grow well at temperatures of 20 - 35C, optimum temperature for growth, development of tilapia is about 25 - 30oC (Rana, 1990). The oxygen threshold: Compared to many species of fish, tilapia can live in an environment with rich in nutrition, such as sewage, water pond... that concentrations of low oxygen dissolves of 1 mg/L. Under experiment conditions, tilapia can tolerate concentrations of oxygen dissolves of less than 0.5 mg/L in a short time. But if the prolonged low concentration of oxygen in water will affect the rate of growth of the fish (Magid and Babiker, 1975). pH threshold: Tilapia grow best in a neutral or slightly alkaline environment with pH of 6.5 - 8.5. It is the ideal range for tilapias growth and development. Tilapia died at pH < 4 or > 11 (Philippart and Ruwet, 1982). Salinity threshold : Tilapia are species adapted to salt. They can live in three of freshwater, brackish and saline (Le Quang Long, 1964). Tilapia O. niloticus is the species can growth fast and adapt to the environment with salinity brackish water from five to ten parts per thousand (Suresh and Kweilin, 1992).

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1.5.7 Indian carp (Labeo rohita, Hamilton (1822))

Indian carp is scientifically name Labeo rohita - Hamilton (1822) of Labeo Cuvier

breed (1817). They are one of three species of Indian carp that introduced Vietnam in August

1982, and have become one of the subjects of freshwater fish farming.

Figure 7. Indian carp (Labeo rohita)

Living characteristics: Indian carp originated from the River Ganges in India,

that quickly become the object of fish culture from South to North in Vietnam. Indian

carp is a species living near the bottom, withstand high temperature of 42 - 43C, but

sensitive with cold temperature, temperature of 12 - 13C cause dead of fish. Suitable

environment for fish: water temperature of 24 - 25C; pH = 7 - 8, oxygen is greater

than 3 mg/L. Oxygen threshold is 0.32 mg/L. The fish can tolerate salinity of 14

parts per thousand.

Nutrient: In the first day old, fish feed small plankton like protozoa, wheel,

single-celled algae etc. From the day 17, the length of bowel is longer than the

length of the body and fish start to eat humus-organic residue.

The most common point in the conclusions that Indian carps are omnivorous

and prefer humus residue therefore their competitiveness is strong. Thank to this

characteristics they have the most common breeding objects.

Growth: Indian carp an reach length of 35 to 45 cm and weight of 0.58

kg in normal culture conditions in 1 year, 2.6 kg in year 2 and year 3 is 5.4 kg.

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II. OBJECTIVE, APPROACH, CONTENT AND METHODOLOGY

2.1. Objective and Approach

2.1.1. General objective

To study method(s) using bioslurry for commercial fish pond and benefits of the practice.

2.1.2. Specific objective

9 Define method(s) using bioslurry for commercial fish pond (eg. Diet of bioslurry and pellets; substitution rate of bioslurry for organic manure; substitution rate of bioslurry for chemical fertilizer; what attention should be paid when using bioslurry for fish farming);

9 Calculate economical, environment and safe product benefits; 9 Develop manual on using bioslurry for commercial fishpond.

2.2. Approach

2.2.1. Desk-study

The study was carried out with desk-study on the overview of the domestic and abroad researches and issues related to the study such as species, percentage of polyculturing in commercial ponds, percentage of bioslurry replacement, combined industrial feed, etc.

2.2.2. Investigation, selection of research place and households

Site selection for study is based on the project database of the Biogas Project on research localities and a list of participating households. We conducted a survey (November and December 2010) and selected four households having eight ponds and five households having biogas plants with appropriate livestock scale. The selected households are households meeting the required conditions for conducting research such as equally area of ponds, depth of the pond, biogas plants, suitable breeding pigs. Priority went to households who are voluntary contribution of capital to participate in research. List of participating households are presented in Table 2

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Table 2. Household participated in research

No. Full name Address Area of

pond (m2) Size of biogas

plant (m3) Remark

1 Nguyen The Toan Cao Lam 2,200 -

Two ponds per

household

2 Nguyen The Sang Cao Lam 2,000 -

3 Nguyen Thi Thao Cao Lam 2,000 -

4 Nguyen Thi Van Cao Lam 2,000 -

5 Tran Duc Thang Ao Sen - 12 10 pigs

6 Nguyen The Thang Ao Sen - 12 12 pigs

7 Ngo Van Lam Ao Sen - 12 10 pigs

8 Ngo Van Diem Ao Sen - 12 10 pigs

9 Nguyen Dinh Luan Ao Sen - 17 30 pigs

Biogas plants are all constructed 3 years ago and located in Dinh Bang village, Tu Son district, Bac Ninh province.

2.3. Research content

2.3.1. Culturing environment

Daily observed changes in the experimental ponds. Take samples of water in ponds before, during and after the experiment to examine changes in the hydration factor, and aquatic life.

2.3.2. Monitor the health of the fish

Health of fish is daily observed. When the fish have healthy problem, measurements have to carry out such as testing sample swabs, drug prevention, treatment and processing environment.

2.3.3. Comprehensive evaluation of bioslurry use in commercial fish pond

All results from the research are comprehensively evaluated, including: the growth rate, commercial size, survival rate, feed conversion ratio, feed cost, total

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cost and evaluation on economic efficiency when using feed pellets, bioslurry use, fresh manure, fish yield when harvesting, comparing the economic efficiency.

2.3.4. Develop draft technical document for utilization of bioslurry for

commercial fish pond

The draft technical documents on using bioslurry in commercial fish has been developed based on the results and content of research after evaluation, compilation and analysis of experimental results, the frequency and volume of bioslurry used in ponds, the amount of bioslurry mixing into feed for the fish are daily recorded by all households. Notebooks of research are checked monthly.

2.4. Research methodology

2.4.1. Experiment equipment:

- Bioslurry was sampled by specialized equipment to transport to the ponds and weight carefully.

- After research on biological characteristics, we refer intergrated treatments on local fish (pond environment, potencial feed supplement, price of commercial fish), collect intergrated treatments as well as amount of types of fish in experiments as following: Tilapia 40%, Grass carp 15%, Bighead Carp 5%, and 10% for each species of Common Carp, Mrigal, Silver Carp and Black Carp. When you use the amount of types of fish essential refer on the fish biological characteristics.

- After studying the biological characteristics, the actual conditions (pond environment, the ability to provide food, the price of each commercial species), and discussions with participating households, we give suggestions on formula for the experiment as follows: Tilapia 40%, Grass Carp 15%, Bighead 5% and 10% each for other species: Common Carp, Indian Carp, Silver Carp, Black Carp. The formula is proposed basing on eating characteristic of each species and their commercial value (households contributed to the including ponds, 50% of the purchase of fingerling fish, 75% of food, therefore cost efficient economy which provided by the formula polyculture that people care). The filter feeding fish: Silver carp and Bighead can use algae in ponds to make ponds water clean. However, these species have low economic value thus the polyculture rate is low (50-10%). Tilapia have the ability to consume food, high resistant and economic value, easy to sell thus have a high rate of polyculture (40%). Grass carp and black carp are species of high economic value but they prefer clean water so they have low polyculture rate (10-15%%). Although common carp has high economic value and high resistance but their growth depends to the number of bottom animals then they should not be raised in high density resulting in low polyculture rate (10%).

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2.4.2. Experiment arrangement

Experiments was carried out on 8 ponds and arrange as below:

Table 3. Arrange experiments

Experiment Description Pond Area (m2)

1 Feed pallets + Fresh manure (10 kg/100m2/week)

P1, P2 1,100

2 Pump bioslurry into fishponds twice a week + feed pallets (10L/100m2/2times/week)

P3, P5 1,000

3 Mix bioslurry with feed pallets with ratio of 1:1(L/kg)

P4, P6 1,000

4 Only feed pallets P7, P8 1,000

The experimental ponds are located in places far away from the household having biogas plants to avoid undefinite impacts of the waste water to flow freely to experimental ponds.

2.4.3. Culture engineering

Details of the general specification follow the prescribed technical standards: the pond that cleared of dusty, dry pond bottoms for 3 days, clearance ponds with 7 - 10 kg/100 m2, water of the pond is filtered through the grid, feeding twice a day, feed management, monitoring on health of fish

2.4.4. Management on pond and feed

Fish are fed twice a day with feed pellets of 3 - 10% of body weight. During culture, daily notes exactly the volume of consumed feed in order to calculate the feed consumed coefficient. Managing measures to the pond and feeding technique are applied in order to minimize losses and achieve economic efficiency. The depth of pond is maintained of 1.5 - 2 m.

2.4.5. Monitoring on environment and fish health during culture

9 Culture environment: Check the water environemtn:

temperature, dissolved oxygen in water, pH, total ammonia, nitrate, nitrite, total by using test analysis kits in order to timely treatment at the research site.

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Checking bio-planton (phytoplankton and zooplankton): Water samples were taken by phytoplankton and zooplankton nets. Sample taking places: taking samples at 4 pond corners, every month for four times

- Quantitative sample taking: The phytoplankton net was used to horizontally get out of the ponds in 8 places like octagon and zigzag. Water samples were contained in 500ml bottle, marked, fixed by Lugol solution and then brought to the laboratory.

- Qualitative sample taking: In sample taking places, we used 20L buckets to get water samples, filtered through phytoplankton and zooplankton rackets. Getting 125ml water to contain 500ml plastic bottles, marked, fixed by Lugol solution and brought to the laboratory.

Identification of species Component (Qualtitative analysis): Pouring 1 - 2 drops to glass, covered by slide and looked through CETI light-microscope with magnification of 40 - 100 times. The samples were looked repeatedly 2 - 3 times. Identification of species Component was refered the doccument below: Nguyen Van Tuyen, 2003; Identification of zooplankton species: According to document of Dang Ngoc Thanh, Pham Van Mien, Thai Tran Bai (1980).

Determination of phytoplankton amount (Quantitative analysis): Sacking gentlely water samples, put 1 drop into Neubauer. Counting the number of agar and zooplankton in center of square with 1mm2. Formula of phytoplankton and zooplankton density: B = A x 104 In Which: B : Density of total counted cells (tb/mL)

A: Counted cells in the center square Density of phytoplankton and zooplankton in 1 little was presented below:

C (tb/l) = B x 103/h In Which: B: Density of phytoplankton and zooplankton (tb/mL)

h: afterfilter coefficient (h = 20000/125 = 1.6 x 102) Determination of zooplankton amount (Quantitative analysis): Individual

counting method of Konkvic (1905): Counting the number of zooplankton by advanced Bogrov method in Microscope with magnification of 40 - 100 times. According to the number of individuals that we looked, calculate the quantity of individual in cubic (A):

C x V' A =

V" x V"' In which: C is the number of counted zooplanktons in V" (individual)

V' is the volume of center samples (100 ml)

V" is the volume of counted samples (ml)

V"' is the volume of pond taking samples (m3)

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9 Fish health: Select healthy and normal shape, free diseases etc. - Fish was bathed with with dilute concentration of 2 - 3% (2 - 3kg of salt per 100 liters of water) for 10 minutes before stocking. - Monitoring fish health during farming duration. - In case of disquality of the environment, timely solutions such as using lime processing environment or using drugs, chemicals, biological products that licensed by the Ministry of Agriculture and Rural Development are used to prevent diseases.

2.4.6. Methods for define growth rate, feed consuming coefficient, living rate

and productivity

The speed growth was monthly checked by examining a random 30 individuals, calculate the average weight to adjust food intake accordingly.

Calculate the average growth speed M1 - M2

M = T

In which: M: Average gain (g/individual/day)

M1: Average weight of individual when stocking

M2: Average weight of individual when harvesting

T: Farming day

Total harvesting quantity (head) Living ratio (% ) = x 100

Total stocking quantity (head) Total amount of feed used (kg)

Feed coefficient = Total amount of weight gained (kg) Total weight of harvesting fish (ton)

Yield (ton/ha) = Culture area (ha) The data on the volume of fish (stock, harvest), food consumption,

environmental data etc are calculated for average value, standard errors, statistical analysis have done on 2003 Excell sheet and SPSS software.

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2.4.7. Method for economic benefit assessment:

Effective breeding including indicators when harvest could be calculated: size of fish, feed consuming coefficient, cost of feed and cost of production. Economic efficiency = total revenue - total expense cost In which: total revenue = quantity of sold fish x product price Total expense cost = breeder cost + feed costs + labor cost + cost depreciation pond.

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CHAPTER II: RESULTS AND DISCUSSION

I. SUBJECT 1: USING BIOSLURRY FOR COMMERCIAL FISHPOND

1. Growth rate

Influence result of using bioslurry for commercial fishpond on growth speed as follows:

1.1. Growth rate of silver cap

Growth result of Vietnam silver cap is presented in Table 4.

Table 4. Growth rate of Vietnam Silver cap

Indicators T1 T2 T3 T4

Average weight when stocking (g/individual)

326.5 326.5 326.5 326.5

Average weight when harvesting

(g/individual) 889.91 881.33 874.83 851.96

Averate growth (g/individual)

563.41 0.78 554.83 1.67 548.33 3.07 525.46 4.46

Farming day (day)

176 176 176 176

Absolute growth (g/individual/day)

3.201 0.004a 3.152 0.009b 3.116 0.017bc 2.986 0.025c

The same scripts in one row mean that there is no statistical significance (P > 0.05)

Through the Table 4, the average weights of the harvested silver carps shot up a peak of 889.91 g/individual in T1 (fresh manure supplemental experiemental), and then reduced in T2, T3 and plunged to 851.96 g/individual in T4 (only feed pallets). At the same time, the absolute growth rates of such fish were fastest in T1 (3.201 g/individual/day) and slowest in T4 (2.986 g/individual/day). The differences in the absolute growth rates of the silver carps in all experiemental treatments are shown in the Firgure 9.

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3.2013.152

3.116

2.986

2.8

2.9

3.0

3.1

3.2

3.3

T 1 T 2 T 3 T 4

Treatments

Absolute growth(g/individual/day)

Figure 9. Absolute growth rates of the silver carps

When using ANOVA analysis of the Excel 2003 software, it is shown that the absolute growth rates of the silver carps in T1(fresh manure supplemental experiemental) was different to those of other treatments (P < 0.05). However, there was no statistical significance on the growth rates of the silver carps in the T2 (Pump bioslurry into fishponds experiemental) and T3 (mix bioslurry with feed pallets experiemental) (P > 0.05). This means the method of using different bioslurry did not affect the growth rates of the silver carps in polyculture ponds of commercial fish species. On the other hand, the growth rates of the Silver carps in T2 and T3 contrasted markedly with that in T4 ((only feed pallets). The growth rates in T2 was statistically different to that in T4 (p < 0.05), whereas T3s was not (p < 0.05).

This can be explained as silver carp is a filter feeding spieces; its main foods are phytoplankton and zooplankton so that its growth rate is influenced by the quantity of the foods in the fishing ponds. It is therefore, when adding an equivalent volume of bioslurry into T2 and T3, the phytoplankton and zooplankton there grew similarly. However, when mixing the bioslurry into industrial fish meal, part of the bioslurry penetrated into the meal and eaten immediately by the spcieces that feed on the industrial meal (common carp, black carp, nile talapia...). This leads to the difference in the volume of the bioslurry in the fishing ponds of T2 in comparison to those of T3. That is why the quantity of phytoplankton and zooplankton in NT3 was lower than T2s but higher than T4s. However the difference between the quantities

23

of phytoplankton and zooplankton of T2 and T3 was not significant enough to lead to discrepancies in the growth rates of the silver carps in the two said experimental treatments. The growth rate of the silver carps in T2 was therefore not statistically different to that in T3 but significantly varies to that in T4. On the contrary, although making use of bioslurry, the quantity of phytoplankton and zooplankton in T3 ponds was not markedly higher than that in T4. That is why the growth rate of the silver carps in T3 was not different to that in T4

When monitoring the growth rates of the silver carps in all experimental treatments, it was recognized that the rates differed throughout the farming months. This is presented in Figure 10.

Figure 10. Growth rates of the Silver carps in checking times

The figure 10 showns that growth rate of silver carp is increased gradually from the first to the fourth checking times, and accelerated faster from the fourth to the sixth checking period. This can be explained that: in the former period (from first farming month to fourth farming month), the pond experienced a lower temperature, and the weather was less sunny than the latter duration; thus, the quantity of phytoplankton and zooplankton in the pond was correspondingly reduced and the carp growth rate was consequently slowlier. On the other hand, in the fry and fingerlings stage, silver carp undergoes a slowlier absolute growth rate than that in the mature period. The Firgure 10 also shows the insignificant differences amongst the growth rates of the Silver Carps in all experimental treatments, only T4s was lower than the others.

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1.2. Growth rate of Grass carp

Table 5. Growth rate of grass carp



538.3 538.3 538.3 538.3


(g/individual) 1,306.66 1,334.83 1,345.77 1,333.96


768.36 5.71 796.53 2.72 807.47 2.26 795.63 0.63

Farming day (day)

176 176 176 176

Absolute growth (g/individual/day) 4.37 0.0334

a 4.53 0.0154b 4.59 0.0129c 4.52 0.0036b

The same scripts in one row mean that there is no statistical significance (P > 0.05)

In the Table 5 showed that, the average weights of the harvested grass carps is shot up a peak of 1,345.77 g/individual in T3 and then is in T2, T4 and smallest average weight is in T1 (1,306.66g/idividual/day). At the same time, the absolute growth rates of such fish were fastest in T3 (4.59 g/individual/day) and slowest in T1 (4.37 g/individual/day). The differences in the absolute growth rates of the grass carps in all experiemental treatments are shown in the Firgure 11.

4.37

4.534.59

4.52

4.20

4.35

4.50

4.65

T 1 T 2 T 3 T 4

Treatments


Figure 11. Absolute growth rates of the grass carps

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ANOVA analysis results indicated that there was a statistically significance in the growth rate of the grass carp in T1 to those of the other experiment treatments (p < 0.05). Thus, the use of fresh pig mannure in the polyculture ponds of commercial fish species has slowed down the growth rate of the grass carp. Such carps in T3 experienced a statistically significant growth rate to those of T2 and T4 (p < 0.05). However, the growth rates of the grass carps in T2 and T4 had no statistical significance (p > 0.05). The two different methods of using bioslurry (Pump directly bioslurry into fishponds and mix bioslurry with feed pallets) has consequently resulted in the different growth rates of the grass carps.

Growth rates of the grass carps in all experimental treatments is presented in Figure 12.

50

100

150

200

250

1st 2nd 3rd 4th 5th 6th

Checking period

Growth (g/individual)

T 1

T 2

T 3

T 4

Figure 12. Growth rates of the grass carp in checking times

In the Figure 12 showed that, the weight growth of the Grass Carps remained consistent amongst all checking times at all experimental treatments, and tended to gradually increase after each checking times. Initially, from the first to the third checking times, the growth rate in T1 was lowest to those of the rest treatments (the line showing the grass carp growth rate in T1 always lay below those of T2, T3 and T4 in the Grass Carp growth rate chart). From the third to fifth checking times, the growth rates in all streatments were relatively alike, all lines came closer. From the fifth to sixth checking times, the growth rates of the grass carps in T2, T3 and T4 were quite the same and higher than T1s.

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1.3. Growth rate of Indian carp

Growth rate of Mud carp is presented in Table 6.

Table 6. Growth rate of Indian carp



215.7 215.7 215.7 215.7


(g/individual) 735.39 710.88 718.55 703.71


519.69 5.74 495.18 1.52 502.85 3.33 488.01 0.87

Farming day (day)

176 176 176 176


2.95 0.0326a 2.81 0.0086b 2.86 0.0189b 2.77 0.0049c

The same scripts in one row mean that there is no statistical significance (P > 0.05).

Through Table 6, its is showed that , the average weights of the harvested Indian carps shot up a peak of 735.39 g/individual in T1 (fresh manure supplemental experiemental), and then reduced in T3 ( mix bioslurry with feed pallets), T2 (pump directly bioslurry into fishponds) and plunged to 703.71 g/individual in T4 (control experiemental - only feed pallets). However, maximum standard declination value is in T1 (5.74) and smallest is in T4 (0.87), this mean showed that growth rate level of Indian carp in T4 is highest and T1 is lowest.

Absolute growth rate of T1 is 2.95 g/individual/day, T2 is 2.81g/individual/day, T3 is 2.86 g/individual/day and lowest is T4 (2.77 g/individual/day).

ANOVA analysis revealed that the absolute growth rate of the Indian carps in T1 had statistically significance with those of the other experimental treatments (P < 0.05), this means the supplementing of fresh pig manure has accelerated the growth rate of such fish in T1 in comparison with those in T2 and T3 wherein bioslurry was added, and that in T4 (the control experiment - only use industrial fish meal). On the other hand, the growth rate of Indian carps in the

27

experiemental treatment where the bioslurry was mixed with feed pallets was faster than that in the experimental treatment where the bioslurry was sploshed into the pond. However, the ANOVA analysis provided no statistical significance between the growth rates of T1 and T2 (p > 0.05). This reflects that two different methods of using bioslurry (sploshing directly to the pond and mixing with feed pallets) have not affected the growth rates of the Indian carps in the polyculture ponds of commercial fish species. When analysing the absolute growth rates of the Indian carps amongst the bioslurry using expirmental treatments and the control treatment (only feed pallets), statistical significance was there to appear (p < 0.05), thus, adding of bioslurry can affect the Indian carp growth rate in the polyculture ponds of commerical fish. The differences in the absolute growth rates of the Indian carp in all experiemental treatments are shown in the Firgure 13.

2.95

2.812.86

2.77

2.6

2.7

2.8

2.9

3.0

T 1 T 2 T 3 T 4

Treatments


Figure 13. Absolute growth rates of the Indian carp

Above-mentioned results indicated that as Indian carps are omnivorous feeding species, their main foods are organic humus, benthic; the Indian carp can also feed well on industrial fish meal. When using fresh pig manure in T1, the increased amount of organic humus, and nutrients has speed up the growth of the benthic in the ponds. Hence, the amount of preferred diets of the Indian carp increased, giving positive effects on the our growth rate. As a result, the absolute growth rate of the Indian Carp in the experimental treatment using fresh pig manure was higher than those in the other treatments. Similarly, when adding bioslurry into the ponds, although the amount of organic humus there is not as much as pig manure brings, the bioslurry is still rich in nutrients so that it can accelerate the

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growth of the benthic within the ponds, leading to a faster growth rate of the Indian Carp. As a result, the growth rates of such fish in the bioslurry-using experimental treatments were higher than that of the control experimental treatment (only feed pallets). However, the growth rates of the Indian Carp of T2 and T3 have no statistical significance (p > 0.05). The reason is that the volume of bioslurry added into the two experimental ponds were equal, so that it did not impringe the growth of benthic even when the bioslurry has partially penetrated into the feed but not mixed into the pond water in the treatments where the bioslurry was mixed with industrial fish meal.

Growth rates of the Indian carp in all experimental treatments is presented in Figure 14.


20

60

100

140

180


Checking period

T 1

T 2

T 3

T 4

Figure 14. Growth rate of Indian carp in all experimental treatments

Look into the graph showing the Indian Carp growths via all checking times, it is clear that from the first to third checking times, there was a gradual and equal increase on the growth of the Indian Carp in all exprimental treatments (the lines showing the growth rates of the Indian Carp were close to each other). From the third to sixth checking times, the growths of the Indian Carp in T2, T3 and T4 were quite similar and lower than that in the T1 (the illustrated growth lines of the Indian Carp in T2, T3 and T4 were close to each other and lower than that of T1). Nevertheless, the growth rate during the fourth and sixth checking period was slowlier than that of the former period (the growth lines of the Indian Carp in all experimental treatments during the first to fourth checking period were less sloping than those of the fourth to sixth checking times). Thus the use of fresh pig manure has affected markedly on the growth of the Indian carp since the forth checking times.

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1.4. Growth rate of Common carp

Growth rate results of Common carp is presented in Table 7.

Table 7. Growth rate of Common carp



268.5 268.5 268.5 268.5


(g/individual) 827.40 820.13 819.63 801.33


558.90 1.34 551.63 2.23 551.13 0.96 532.83 4.93

Farming day (day)

176 176 176 176


3.176 0.008a 3.134 0.013ab 3.131 0.005b 3.027 0.028c


Table 7 showed that the average weights of the harvested Common carp shot up a peak of 558.9 g/fish in T1 (fresh manure supplement), and then reduced in T2 (pump directly bioslurry into fishponds), T3 (mix bioslurry with feed pallets) and plunged to 523.83 g/fish in T4 (control experimental - only feed pallets). However, smallest standard diclination in T3 is 0.96g/individual, and then T1, T2 and biggest is T4 (4.93g/individual). At the same time, the absolute growth rates of such fish were fastest in T3 and slowest in T4. This much when polyculturing serveral commercial fish species, if fresh pig manure or bioslurry is added, the uniformity of the Common Carp sizes is higher than that of just using feed pallets.

Absolute growth rate in Common carp in T1 is 3.176 g/individual/day, T2 is 3.134 g/individual/day, T3 is 3.131 g/individual/day and lowest is in T4 (3.027 g/individual/day). When using ANOVA analysis, it is clear that the absolute growth rate of the Common arp in T1 was statistically different to those of the Common carp in T3 and T4 (P < 0.05), but not different to that in T2. Thus, the adding of fresh pig manure has increased the growth of the Common carp in T1 than in T3 and T4.

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However, when analysing the growth rate of the Common carp at the bioslurry using treatments, there was no statistical significances (p > 0.05). This means the different methods of using bioslurry (ploshing directly into the ponds and mixing with the fish meal) have not impringed the growth rates of the common carp in the polycuture ponds of commercial fish species. When analysing the absolute growth rates of the Common carp in the bioslurry using experimental treatments in comparison with that of the control treatment, a statistical significance was recorded (p < 0.05). Thus, the adding of bioslurry into the commericial polyculture ponds can give positive effects on the carp growth rates.

The differences in the absolute growth rates of the Common Carp in all experimental is presented in Figure 15.

3.1763.134 3.134

3.027

2.80

2.90

3.00

3.10

3.20

3.30

T 1 T 2 T 3 T 4

Treatments


Figure 15. Growth rate of Common carp in all experimental

The differences in the absolute growth rates of the Common carp amongst all experimental treatments are explained as: because the Common carp are omnivorous feeding species, their main fodds are benthic, it can either feed well on feed pallets. When using fresh pig manure in T1, the incrased amount of organic humus and nutrients has speed up the benthic growth in the ponds. Thus, the amount of prefered diets for the Common Carp increased, positively accelarting the growth rate of the carp. As a result, the absolute growth rate of the Common carp in the experimental treatment using fresh pig manure was higher than those of T3 and T4 ones. Similarly, when adding the bioslurry into the ponds, the amount of organic humus was not as much as the pig manure does, but the slurry has sustaintial nutrients so that it can accelerate the growth of the benthic within the ponds, leading

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to a faster growth rate of the Common carp. As a result, the growth rates of the Common carp in the bioslurry-using experimental treatments were higher than that of the control treatment. However, the two methods of ploshing directly the bioslurry and mixing the bioslurry with fish meal have no differences on the Common carp growth rates. The reason is that the volume of bioslurry added into the two experimental ponds were equal, so that it did not impringe the development of benthic; even when part of the slurry has penetrated into the feed but not mixed into the pond water.

Growth rates of the Common carp in all experimental treatments is presented in Figure 16.


30

60

90

120

150

180


Checking period

T 1

T 2

T 3

T 4

Figure 16. Growth rates of the Common carp in all experimental treatments

The Common carp growth graph during all checking times shows that from the first to third checking time, there was a similar increase on the growth of the common carp at all expriments. From the third to sixth checking time, the growths of the Common carp at T1, T2 and T3 are quite similar and higher than that of NT4 (the growth graph lines of Common carp at NT1, NT2 and NT3 are close to each other and higher than that of NT4). However, the growth rate in the period of the first to second checking time was slowlier than that of the second to sixth checking period (the sloping level of the growth lines in all experiments during the former period was smaller to that of the latter one). Thus the use of fresh pig manure has positively impacts on the growth of the Common carp since the third checking times.

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1.5. Growth rate of Black carp

Growth rate results of Common carp is presented in Table 8.

Table 8. Growth rate of Black carp



212.6 212.6 212.6 212.6


(g/individual) 1,069.17 1,097.26 1,111.29 1,096.27


856.75 5.95 884.66 3.46 898.69 5.41 883.67 5.30

Farming day (day)

176 176 176 176


4.867 0.0339a 5.026 0.0197b 5.106 0.0307b 5.021 0.0301b


The Table 8 showed that the average weights of the harvested Black carps shot up a peak of 898.69 g/individual in T3, and then reduced in T2, T4 and plunged to 856.75 g/individual in T1. However, smallest standard diclination in T2 is 3.46 g/individual, and then T3, T4 and biggest is T1 (5.95g/individual). This mean showed that uniform level of Black carp in T2 is highest and T1 is lowest.

The absolute growth rates of such fish were fastest in T3 (5.106 g/individual/day) and then T2 (4.687g/individual/day), T4 (5.021 g/individual/day) and slowest in T1 (4.687 g/individual/day).

When using ANOVA analysis, it shows that the absolute growth rate of the Black carp of the T1 (supplement fresh pig manure) has statistically significant difference with those of other experiments (P < 0.05). This means the supplementing of fresh pig manure has accelerated the growth rate of the the Black carp of T1 in comparison with those of T2 (pump directly bioslurry into fishponds), T3 (mix bioslurry with feed pallets), T4 (control experiment - only feed pallets) . On the other hand, when analysing the growth rates of the Black carp, it is recognized that there was no statistical discrepancy beween the experiments using bioslurry as well

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as between these with the control experienment (p > 0.05). This reflects that using bioslurry and using different methods for adding bioslurry did not affected the Black carp growth rate in the polyculture pond of commercial fish.

The differences in the absolute growth rates of the Black carp in all experimental is presented in Figure 17.

4.867

5.0265.106

5.021

4.6

4.8

5.0

5.2

T 1 T 2 T 3 T 4

Treatments


Figure 17. Absolute growth rates of the Black carp

The differences and similarities of the growth rates of the Black carp of all experimental treatments are explained as follows: As far as we know, Black carp are the species prefering clean water, requiring high transparency and having high demand for disolved oxygen. That is why when whe used fresh pig manure in T1, the amount of nutrient in the ponds went up but the preferred diets of the Black carp were not increased; the water quality in the pond was either decreased. When adding the fresh pig manure, the decomposition of organic matters in the manure will consume disolved oxygen in the water, leading to a reduction of disolved oxygen concent. At the same time, the manure stimulates the growth of plankton in the water, reducing the water trasparency, and leads to a reduction of the disolved oxygen content at night due to the strong respiration of the plankton. On the contrary, in cases of using bioslurry or not using bioslurry combined with manure, a lower amount of organic humus, lower density of plankton were recorded in the ponds, the disolved oxygen content at night was higher. This beneficially influenced the growth of the Black carp. Consequently, the growth rate of the Black carp at the experimental treatment using the fresh pig manure was slowlier than that of the Black carp in the other experimental treatments. Concurrently, the absolute growth rates of the Black carp amongst the bioslurry and control experimental treatments had no discrepancy.

Growth rates of the Black carp in all experimental treatments is presented in Figure 18

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50

100

150

200

250


Checking period

T 1

T 2

T 3

T 4

Figure 18. Growth rates of the Black carp in all experimental treatments

The growth rates of the Black carp in all experiemental treatments were similar throughout all checking times, just only T1s was lower than those of the other treatments (the growh lines showing the growth rates of such fish in all experimental treatment were close to each oher, except the T1 which lay below the others). On the other hand, the graph has several rough sections, reflecting that the growth rates varied throughout the monitoring times. From the first to second checking times, the growth rates were slow, illustrated by a marginal upward trend on the graph. From the second to the fourth checking times, the growth rates were higher and reflected by a steep slope on the graph. From the fourth to the fifth checking times, the rates were slowlier, reflected by a less steep slope. From the fifth to sixth checking times, the growth rates went up again, the illustrating lines were steeper in comparison to all previous periods.

This can be explained as follows: From the first to the fourth checking times, the pond temperature rose gradually (from 11C to 25C); When the temperature increased and still under the suitable theshold for the Black carp growth, it can stimulate the growth rates of the fish. However, the characteristics of the species are that during the period of increasing from 200 to 1200 g/fish, the growth rates of the fish go in a direct proportion with its weight. Hence, its growth rates from the first to the second checking times were low, and then increased from the second to fourth checking times. From the fourth to fifth checking times, the growth rates reduced since the fish got deseases and had to take medicine. After the fifth checking times, the growth rates increased again since the epidemic was cured, and the fish got recovered,

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