LIST OF TABLES
Table 4.1: Number of red blood cells in experimental fish infected with cypermethrin 31
Table 4.2: Experimental white blood cell count of fish infected with cypermethrin 32
Table 4.3: Hemoglobin content (mmol/l) of fish infected with cypermethrin. 33 Table 4.4: Hemoglobin ratio (%) of fish infected with cypermethrin. 34
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Table 4.5: Experimental red blood cell volume of fish infected with cypermethrin 34
Table 4.6: MCH (pg) of experimental fish infected with cypermethrin 35
Table 4.7: MCHC (%) of experimental fish infected with cypermethrin 36
Table 4.8: Hematological parameters of fish injected with E.ictaluri 37 bacteria
LIST OF IMAGES
Figure 2.7: Structure of Cypermethrin 10
Figure 4.1 Fish with liver pus disease 27
Figure 4.2 Types of white blood cells 30
LIST OF ABBREVIATIONS
Mekong Delta Mekong Delta Plant Protection Plant Protection
LC50 lethal concentration 50 (threshold causing death of 50% of test organisms) MCV mean cell volume (Red blood cell volume)
MCH mean cell hemoglobin (Mean cell hemoglobin)
MCHC mean cell hemoglobin concentration
CHAPTER 1:
PROBLEM STATEMENT
1.1 Introduction
It can be said that currently in the world there are hundreds of aquatic species that are domesticated and used for aquaculture in all three environments: fresh, brackish and saltwater. In the group of freshwater species, pangasius is a catfish species with high economic value. In recent years, pangasius has been one of the important farming species in the Mekong Delta. In Can Tho, the farming area up to November was 14,113 hectares, equal to 110% compared to the same period in 2009, of which the pangasius farming area was 581 hectares; farming output reached 164,579 tons, exceeding 8% over the same period. In Vinh Long, the pangasius farming area was 405.9 hectares and the output reached 108,746 tons.
With the rapid expansion of aquaculture, environmental degradation and disease have become major obstacles to the sustainable development of freshwater aquaculture in Vietnam. According to Pham Dinh Khoi (2009), in the past 5 years, environmental pollution and disease have reduced the average survival rate of farmed fish from 90% to 80%. Ly Thi Thanh Loan and colleagues (2006) when collecting and isolating pathogenic bacteria on Tra fish in the Mekong Delta, liver and kidney diseases caused by Clostridium sp. accounted for 69.38%, hemorrhage caused by Aeromonas sp. accounted for 44.89% and Pseudomonas sp. accounted for 4.08%.
However, the current trend of disease prevention and treatment in freshwater fish in our country is still mainly based on the use of antibiotics and chemicals, including chemicals banned from use in aquaculture, causing many difficulties in exporting Vietnamese seafood due to the increasing list of drugs and chemicals banned from use in aquaculture.
Fish hematological parameters are increasingly being studied in aquaculture disease management, and can be used to indicate the health status of fish as well as water quality, as the blood in the gills is directly related to the water environment and adverse environmental changes can be reflected in the circulatory system (Mulcahy, 1975). There are several scientific studies on the effects of pesticides on fish hematological parameters (Srivastava, 1988; Khattak and Hafeez, 1996; Tavares et al ., 1999; Svoboda et al ., 2001). The changes in hematological parameters and excretion function at different stages and concentrations of pesticides in tilapia Orieochromis mossambicus (Sampath et al ., 1993).
The question is how there are differences in some hematological indicators of pangasius when there is an impact of biological and chemical agents. For the above reasons, the topic: "Effect of infection with Edwardsiella ictaluri bacteria and Cyrus pesticide on changes in some hematological indicators of pangasius ( Pangasianodon hypophthalmus )" was carried out.
1.2 Objectives of the topic
Determine some hematological factors of healthy pangasius fish and fish infected by bacteria and chemicals, thereby evaluating the changes in some hematological indicators of fish infected by diseases and chemicals to provide scientific data for diagnosis and health assessment in farmed fish.
1.3 Content of the topic
- Determination of LC 50 -96 hours of pesticide Cyrux 25EC (active ingredient cypermethrin) on pangasius fingerlings.
- Effects of Edwardsiella ictaluri CT 258 bacteria on some hematological parameters (red blood cells, white blood cells, hematorite and hemoglobin) of pangasius fingerlings.
- Effects of pesticide Cyrux 25EC on some hematological indicators (red blood cells, white blood cells, hematorite and hemoglobin) of pangasius fingerlings.
1.4 Project implementation time
From August 2009 to December 2010
CHAPTER 2: OVERVIEW OF DOCUMENTS
2.1 Biological characteristics of pangasius fish
2.1.1 Classification : Pangasius is one of 11 species of the Pangasiidae family that have been identified in the Mekong River. The most recent classification document by author Rainboth classifies Pangasius in the genus Pangasianodon .
Order Siluriformes Family Pangasiidae
Genus Pangasianodon
Species Pangasianodon hypophthalmus (Sauvage, 1878)
2.1.2 Biological characteristics
Pangasius can live in environments with lots of organic debris, stagnant water, and low dissolved oxygen (Duong Nhut Long, 2003). Pangasius exhibits a broad, bottom-feeding and omnivorous nature, but is easily able to switch between food types. In pond conditions, it can easily adapt to many types of food of animal and plant origin (Le Nhu Xuan, 2000). Pangasius lives mainly in fresh water, can live in brackish water (salt concentration 7-10‰), can tolerate alum water with pH = 4.5, easily dies at low temperatures below 15 o C, but can withstand heat up to 39 o C.
(VINAFIS, 2004). Pangasius has a higher number of red blood cells in its blood than other fish species. It has accessory respiratory organs and can also breathe through its air bladder and skin, so it can tolerate water environments with very low dissolved oxygen (Le Nhu Xuan, 2000).
2.1.3 Current status of pangasius farming in the Mekong Delta
The Mekong Delta has special potential and natural advantages for developing pangasius farming. The average pangasius farming productivity reaches 150-300 tons/ha, the pangasius farming area of the Mekong Delta in 2007 reached 7000 ha, reaching an output of over 1 million tons with an export value of over 1 billion USD (Ministry of Agriculture and Rural Development, 2008). The whole region has 157 hatcheries, in 2007 and produced 4.1 billion fish fry, enough to meet the farming demand (Ministry of Agriculture and Rural Development, 2008).
In the Mekong Delta, the intensive pangasius farming movement has developed strongly in the areas along the Tien and Hau rivers, especially in An Giang, Dong Thap, Vinh Long provinces and Can Tho City. However, due to spontaneous development in area and high increase in farming density from 20-30 fish/m2 to 50-70 fish/m2 , in addition to increasing output, income for
Farmers have led to the farming environment in some places showing signs of pollution and frequent outbreaks of disease causing great economic losses. Some common diseases in farmed pangasius are ulcers, red spots, white spots, necrosis and hemorrhage of fins, slime loss, and pus-filled liver and kidney disease.
2.2 Blood physiology and hematology of fish
In fish, blood accounts for 2-4% of body weight, less than in other vertebrates (5-8%). Hematological parameters of fish are related to age, sex, diet, species, season of the year and water temperature (Branson, 1993).
2.2.1 Functions of blood
Fish blood is similar to other vertebrates and consists of body fluids and cellular components (Hibiya, 1982). Fish blood also has the function of transporting (gas, nutrients, products of metabolism), regulating body fluids, protecting and maintaining the internal environment of the body (Do Thi Thanh Huong and Tran Thi Thanh Hien, 2000).
2.2.2 Composition and physical and chemical properties of blood
Blood cells include red blood cells, white blood cells and platelets (Do Thi Thanh Huong and Tran Thi Thanh Hien, 2000).
Red blood cells: According to Supranee et al . (1991), red blood cells are divided into two groups: mature red blood cells and immature red blood cells. In fish, they are oval in shape, convex on both sides, with a nucleus in the middle, and their size varies depending on the species of fish, the largest being cartilaginous fish, round-mouthed fish, and then bony fish. In catfish, they are about 6.16×6.87 µm. Red blood cells vary according to the physiological state of the fish, the species, the diet, the age, and the fluctuations of environmental factors. Red blood cells are elastic cells that can stretch and change shape to enter the capillaries. The chemical composition of red blood cells includes water (60%), dry matter (40%), mainly hemoglobin (90%). Each red blood cell contains about 340 million hemoglobin molecules. In addition, there are proteins, lipids, inorganic salts, and enzymes. The amount of hemoglobin changes according to the change in the number of red blood cells (Do Thi Thanh Huong and Tran Thi Thanh Hien, 2000).
Leukocytes: According to Do Thi Thanh Huong and Tran Thi Thanh Hien (2000), leukocytes are cells with large nuclei, larger in size than red blood cells. The number of leukocytes varies depending on species, physiology, age, nutrition, temperature, and sexual maturity. The function of leukocytes is to protect the body against invasion by phagocytosis (by monocytes and neutrophil leukocytes) and to create antibodies (by
Lymphocytes), which contribute to ovulation and digestion. Based on the staining and dyeing properties, they are divided into two groups: granular leukocytes and agranular leukocytes.
Granular leukocytes: The cytoplasm of granular leukocytes is stained and the nucleus has many lobes. Depending on the type of dye, people divide them into acidophil leukocytes, basodophil leukocytes and neutrophil leukocytes. Neutrophil leukocytes are the most numerous in the total number of leukocytes, accounting for 60-70%. They are abundant in peripheral blood, play a key role in inflammatory reactions, and have the ability to eat small cells, so they are called macrophages. Therefore, when the body is injured, neutrophils come to phagocytose bacteria and foreign objects. The nucleus of this leukocyte is always changing. When young, the nucleus is rod-shaped, when old, the nucleus is divided into lobes, which can be from 2-5 lobes.
Acidophil leukocytes: account for 2-4% of total leukocytes, diameter from 10-12 microns, granules in the cytoplasm stain acid. Granules in the cytoplasm of this leukocyte are larger than granules in the cytoplasm of other granular leukocytes. The number of acidophils increases when the body is infected with bacteria, infected with intestinal parasites and allergic states as well as injected with foreign proteins into the body.
Basodophil leucocyte: accounts for 0.5-1% of total leukocytes. Diameter is 8-10 microns. The granules in the cytoplasm absorb alkaline dye. In some fish species, this type of leukocyte is absent. Its function is not clear, but when there is a lack of vitamin A, this type of leukocyte increases significantly.
Granulocytes: are the type that do not have stained granules and non-lobed nuclei. There are 2 types: monocytes (have 1 nucleus) and lymphocytes (have many nuclei).
Monocyte : has a nucleus, binds to tissues of target organs (kidneys, spleen, digestive tract,...) to perform phagocytic function right in the blood vessels, only exists for a few days in the blood circulation, participates in the process of antigen presentation.
Lymphocytes : account for about 20-25% of total leukocytes, in young animals can account for up to 50%. Have the ability to phagocytose when out of the blood vessels into connective tissue. Have an important role in the immune system after binding to tissues of target organs.
Platelets: small in size, about the size of a red blood cell nucleus, unstable spindle-shaped, exist in the blood for 5-9 days, have a large nucleus, have a thin cytoplasmic layer that plays a role