History of White Feces Disease and How to Handle it
In early 2010, tempted by the high price of shrimp, many shrimp farmers in Thailand decided to increase stocking density to achieve high levels of production. Therefore, an increase in water temperature (> 32oC) and an increase in the amount of feed given, resulting in increased levels of organic matter at the bottom of the pond. High levels of organic matter at the bottom of the pond cause the emergence of new pathologies namely Vibrio parahaemolyticus (green colony), V. fluvialis (yellow colony), V. vulnificus (green colony), V. mimicus (green colony), V. alginolyticus and V. cholera. The six types of pathogenic vibrio are allegedly the cause of the emergence of WFD disease or often referred to as white feces disease.
This disease was first detected in Penaeus Monodon, which is cultivated in waters with low salinity, but then spread to all shrimp production areas in Thailand, where to date 99% have switched to Litopenaeus Vannamei cultivation.
From the results of subsequent analyses, Gregarine was found in shrimp feces. Gregarine is a Nemaptosis sp. Gregarine is an endoparasite found in shrimp midget. This protozoan is mostly observed in the trophozoite stage (an active form of protozoa that can invade tissues). Damage caused by Gregarine is minor, but if in large conditions it can cause damage to the stomach edge and become an intermediary for bacterial infections.
This disease occurs in pond bottom quality that is different from normal conditions, which results in deteriorating water quality. Peak death rates are seen at very low oxygen levels (3.0 mg / l) and also low levels of alkalinity (<80 ppm).
The addition of organic acids (Acetic Acid, Formic Acid, Lactic Acid, and Propionate Acid) of 10 ml/kg of feed and probiotics were allegedly able to help prevent shrimp from WFD infection. Organic acids are recommended to be added to the feed is in liquid form, because it is more easily seep into the feed.
DISEASE SCENARIO
This disease occurs in pond bottom quality that is different from normal conditions, which results in deteriorating water quality. Peak death rates are seen at very low oxygen levels (3.0 mg / l) and also low levels of alkalinity (<80 ppm).
An early indication of this disease is the appearance of white stools (like a thread) that float on the surface of the water and anco.
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| White Feces Shrimp floats on the surface of the water |
Characteristic of viruses
Clinical symptoms that can be observed include Blackish color changes in the gills caused by the presence of epibiotic protozoa, loose shells and shrinkage of the hepatopancreas. The intestine is not filled with food but there are strands of white feces. Sometimes white stool (2-3 cm long) can be seen on the diseased tail of the shrimp. Besides contracting, the hepatopancreas also changes color to blue and white. (Figure 2)
WFD can have an impact on shrimp in the form of decreased appetite, stunted growth, and chronic death. Feed conversion (FCR) also reported an increase of 2-3 compared to healthy shrimp ranging from 1.4 to 1.7.
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| Physical shrimp infected with White Feces Disease (WFD) |
Some things that can be done to prevent WFD include:
- Control of feed program
- Good management of pond bottom and DO
- Addition of organic acids to feed
- Adding probiotics to clean pond bottom
- Giving immunostimulant in feed
The addition of organic acids (Acetic Acid, Formic Acid, Lactic Acid, and Propionate Acid) of 10 ml/kg of feed and probiotics were allegedly able to help prevent shrimp from WFD infection. Organic acids are recommended to be added to the feed is in liquid form, because it is more easily seep into the feed.
