HEPATOPANCREAS RELATED DISEASES OF PENAEUS VANNAMEI.

Shrimp hepatitis, also known as hepatopancreatic necrosis syndrome (AHPNS) or early death syndrome (EMS), is a toxic disease, the incidence of this disease is up to 90% in recent years. EMS is also the main causes of death of shrimp. EMS mainly damages the hepatopancreas and gastrointestinal tract of the digestive system of shrimp, and eventually causes the severe liver, pancreas and gastrointestinal inflammation, and the infectious shrimp is generally weak. Nowadays, the most common symptoms of P. vannamei farming are hepatopancreas and alimentary tract problems.

Liver and pancreas also known as the digestive gland, is evolved from the midgut, its main function is to digest enzymes, absorption and storage of nutrients, manufacturing clotting factor, metabolism of various vitamins, fats, proteins, hormones. Once the shrimp hepatopancreas has problems, it will lead to shrimp chronic hepatitis and serious complications. How to protect the liver and pancreas of shrimp has become a top priority.

First, before talking about the protection of the hepatopancreas, let's take a look at the causes of liver and pancreatic lesions in shrimp:

1. Feed quality problems. In recent years, feed raw materials prices rose rapidly, feed prices are relatively rising, many farmers in order to save costs, feed the poor quality of feed, or improper storage of food, easy moldy, resulting in a lot of mycotoxins. Shrimp eat poor quality or moldy food, it is easy to cause hepatitis, coupled with the external environment stimulus can lead to a large number of deaths shrimp.

2.Water quality problems. Poor water quality, no matter how good the shrimp is also easy to get sick. The factors that affect water quality are the following:

Microorganisms: Water grows in many microorganisms, shrimp usually by filtering the microorganisms in the water to obtain nutrients, but if the water is not suitable for the consumption of microorganisms in shrimp, it is easy to cause gastrointestinal diseases.

Toxins: Algae toxins, bacterial toxins, mycotoxins, free radicals, ammonia nitrogen, nitrite and other toxic and harmful substances through the liver or blood circulation system into the liver, increase liver detoxification or immune burden, resulting in shrimp liver dysfunction or failure.

Salinity changes: Taking P. vannamei as an example, the optimum growth salinity of P. vannamei is 10-25 , with a lower incidence in this salinity, but less likely to occur at low salinity and high salinity.

Heavy metals: In hepatopancreas, an important small molecule protein, metallothionein, is a kind of small molecule protein which can chelate metal ions and regulate the storage and transportation of trace elements (mainly Cu and Zn) And metabolism and has the function of detoxification of heavy metal poisoning and scavenging oxygen free radicals.

Temperature: The drastic temperature change led to the metabolic disorder of shrimp and the decrease of the antioxidant enzyme activities of shrimp and hepatopancreas. The more temperature changes, the more vulnerable the shrimp was to oxidative damage, which led to the decrease of disease resistance and easy death of shrimp.

 Shrimp liver conditioning. If you mess with liver protection drugs, but also very easy to disease. In many cases, farmers in order to shrimp liver, will use some drugs, but with improper use, but will give the liver caused by shrimp burden. This is why sometimes there is no reason to add less drug deaths and increase drug deaths if added.

Unreasonable feeding. Feeding the amount of food inappropriate, too much or too little, will give the liver and pancreas of shrimp cause some digestive pressure, but also very easy to onset, the incidence of the most common symptom is the liver swelling.

 Second, white prawn in the South American culture process, the key in liver protection, liver disease is sick. Liver and pancreas are shrimp's immune organs, but also detoxification weapon. How to correctly prevent P. vannamei liver disease?

1. The correct preservation of feed to prevent mildew feed mold mycotoxin;

2.Reasonable regulation of water quality, always concerned about the salinity of water changes, regular removal of harmful algae and microorganisms in water, shrimp to provide an excellent growth environment;

3. A reasonable feeding, feeding should be scientific and ration

 4. The rational use of liver products

 Liver, intends to enhance the shrimp hepatopancreas digestion and detoxification capacity, improve their ability to resist stress, this is a good way once and for all. However, ordinary liver drugs can only treat the surface problems, fundamental problems can not be solved, shrimp or hepatitis will be sick.