Analysis of the prevention and treatment of shrimp white feces

Analysis of the prevention and treatment of shrimp ' white feces ' 

--- broken jejunum, floating white linear sticky feces

Litopenaeus vannamei is the main economic species of shrimp aquaculture in the world because of its fast growth, short breeding cycle, high yield and economic benefits.

The symptoms of diseased shrimp were not obvious at the beginning of the disease. With the development of the disease, floating white linear viscous feces could be seen on the surface of the lower tuyere of the pond. The intestinal tract of the diseased shrimp was ' broken intestine ' and jejunum. When the disease was serious, the whole intestine became milky white, showing ' white intestine ', and the hepatopancreas was atrophy and blurred. Penaeus vannamei breeding industry is seriously plagued by high incidence and strong infectivity of fecal syndrome. Through electron microscope observation, the white stool syndrome is a aggregation formed in the lumen after the microvilli of glandular epithelium fall off, and when the number is large and serious, white feces are formed in shrimp. Due to the high nutritional value and economic benefits of Penaeus vannamei, the majority of aquatic friends still pay high attention to Penaeus vannamei. This paper will focus on another common disease of Penaeus vannamei, white feces syndrome ( WFS ), and analyze it in detail to understand the causes, characteristics and prevention measures of  white feces.

1. ' White feces' features

Shrimp excreted in vitro feces slender white, sticky, often floating on the surface, large, long-term aggregation will emit odor. In the early stage of the disease, shrimp fed normally and had no obvious changes in body surface. However, with the aggravation of the disease, gradually appear to eat slowly or even not to eat or shrimp lean ( shell meat separation ), and accompanied by swimming ponds and ' steal death ' ( shrimp intestinal red or intestinal white pus ). The typical intestinal pathological changes were the proliferation of submucosa cells and the shedding of epithelial cells. The proliferative and fibrotic cell layer fell off as a whole, and could fall off many times to form multiple white stools.

2.  Cause analysis of ' white feces'

2.1. Bacterial infection

Bacterial infection is the main cause of white stool disease in shrimp. A large number of pathogenic bacteria such as Vibrio parahaemolyticus, Vibrio harveyi, Vibrio vulnificus and Vibrio cholerae were detected from diseased shrimp, and the hepatopancreas and intestine of shrimp were infected. Vibrio cholerae incubation period is long, shallow disease, not easy to detect. Once slow or not to eat is already late, it is basically difficult to save, the disease late hepatopancreas necrosis, and a large number of white mucus plug the intestine. The intestinal tract caused by Vibrio parahaemolyticus, Vibrio harveyi, Vibrio vulnificus is redr, and it is also often accompanied by yellow legs, red whiskers, red tail, black gills, and often accompanied by abnormal water quality. In view of this situation, the use of antimicrobial agents, supplemented by Bacillus and lactic acid bacteria products, will achieve better treatment effect.

2.2. Algae toxin

Algae toxins have a class of liver toxins, into the shrimp body, will lead to hepatopancreas swelling, atrophy, bleeding, necrosis and gastrointestinal inflammation, necrosis and other lesions, open liver visible obvious black, yellow or red liquid outflow, and shrimp body without obvious disease, this situation treatment first stop feeding 3 ~ 5 days, and then use biological organic acids, humic acid, multidimensional products such as water detoxification, improve the immunity of shrimp, the situation will be effectively alleviated.

2.3. Chronic poisoning

Chronic poisoning is generally caused by deterioration of water quality and long-term deterioration of sediment. South American white shrimp ( Penaeus vannamei ) is a benthic organism, which lives in the middle and lower layers of water. Due to the accumulation of residual bait, feces, dead algae and the abuse of flocculation, the water quality, substrate heat, ozone, pan-acid, biological and chemical oxygen consumption are large, and toxic substances such as ammonia nitrogen, nitrite, hydrogen sulfide and microcystins are seriously exceeded. Being a veritable “ polytoxic layer ” has not been eliminated in a timely manner, which will increase the liver and pancreas burden of shrimp, erode intestinal mucosa, and eventually lead to “ white stool ”. Faced with this situation, the first appropriate water exchange, and then the use of Bacillus sprinkling water timely decomposition of organic matter at the bottom of the conversion tank ; the water quality will be improved and the ' white stool ' will be alleviated by using oxygen-enriched bottom modifier to increase the dissolved oxygen at the bottom.

2.4. Mycotoxins

The feed raw materials in hot and humid seasons are often mouldy. Due to poor raw materials and improper storage methods, mycotoxins in feed often exceed the standard. Long-term consumption of moldy feed resulted in liver cell necrosis, hepatopancreatic detoxification and digestive dysfunction, resulting in necrosis of intestinal mucosa and blood cells. Mycotoxin inhibited the immune system of shrimp and was prone to large-scale diseases.

    3.Prevention and control of shrimp ' white feces '

Penaeus vannamei ' white feces ' is a kind of intractable enteritis disease, which is difficult to cure. It is the phenomenon that intestinal epithelial cells in shrimp are stimulated by the outside world and fall off with feces. White stool disease is related to factors such as water quality deterioration, feed deterioration and bacterial infection. A long time will form ' steal death '. Therefore, it is necessary to do a good job of prevention in the early stage of disease, and have a certain sensitivity to water quality changes, so as to achieve early prevention, early detection and early treatment.

3.1. Stolen death

Stealing death, also known as Deady Bottom Disease, is a disease that occurs in the late mid-term of South American white shrimp aquaculture. The pond accumulates a large number of residual baits, feces and dead algae. After the decomposition of heterotrophic bacteria, a large number of nitrogen-containing harmful substances such as ammonia are produced. After the role of nitrite bacteria, it is transformed into nitrite, resulting in chronic poisoning of shrimp, resulting in metabolic disorder, and often died of hypoxia at the bottom of the pond. If blind use of antibiotics will accelerating death.

Measures :

( 1 ) Pond rest : After one year of culture, it can clear the pond sun, kill pathogens, restore soil potential, and lay the foundation for the next year.

( 2 ) Reasonable stocking : avoid high density breeding, reasonable stocking not only good water quality, accelerate the growth of shrimp.

( 3 ) Appropriate mixed culture : meat-eating fish, diseased shrimp and dead shrimp can reduce the outbreak of shrimp infection.

( 4 ) Maintaining water environment : regular spraying of photosynthetic bacteria, Bacillus, EM bacteria, nitrifying bacteria, etc. Regular bottom change, observe sediment color, odor changes.

( 5 ) Add beneficial bacteria to feed : use oral and external application. Oral conditioning gastrointestinal products, external drops of enterocolitis bacteria. If infected with vibrio, then vibrio vermiculi freeze-dried powder.

3.2. White feces

At the beginning of the disease, the symptoms of diseased shrimp were not obvious. With the development of the disease, floating white linear viscous feces could be seen on the surface of the lower tuyere of the pond. The intestinal tract of diseased shrimp was ' broken intestine ' and jejunum. When the disease was serious, the whole intestinal tract became milky white, showing ' white intestine ', and the hepatopancreas was atrophy and blurred.

Measures :

( 1 ) Diet reduction : Diet reduction is a necessary way to help solve the ' white feces ', which can slow down the occurrence of white feces.

( 2 ) Add beneficial bacteria to feed : use the internal and external feeding modes. Oral conditioning gastrointestinal products,such as the Aquatic feed mixed bacteria 10 billion-50 billion,it can regulate the stomach and intestines, to prevent the effect of disease;External drops of Enhanced water purification complex bacteria,it can purify water quality, reduce ammonia nitrogen, give fish and shrimp a safe and healthy breeding environment.