In recent years, due to long-term high-density intensive breeding and the use of feed with high nutritional indicators, the outbreak of grass carp liver disease (hepatobiliary disease) has led to serious economic losses. This disease is often complicated with hemorrhagic disease and gill rot disease, the larger the fish, the more fish they eat, the more serious the disease, and the more deaths.
First, the main function of the liver
1. Secretion of bile: it can emulsify fat and promote the digestion and absorption of fat. The gallbladder is the place where bile is stored.
2. Metabolic function: various nutrients absorbed from the digestive tract enter the vein into the liver, processed and processed in liver cells, and synthesized important substances needed by the body, such as protein, fibrin and part of globulins. Liver cells also synthesize and break down glycogen, which is involved in the metabolism of vitamins and hormones.
3. Detoxification effect: some toxic substances absorbed by the intestine and metabolized and toxic substances in the body are transformed or combined by liver cells to eliminate or reduce toxicity.
4. Defense function: Hepatic macrophages have an active phagocytic ability, which can eliminate bacteria, harmful substances and senescent white blood cells.
Second, how is hepatobiliary disease caused
1. Feed compound feed with high nutritional indicators. This is the main reason, in order to stimulate the rapid growth of fish, the use of high nutritional indicators of the compound feed feeding grass carp, such as the use of fish fingerling feed feeding adult fish and feeding too much, resulting in the emergence of "fat" and fatty liver.
2. Lack of trace elements induces liver disease. The lack of trace elements such as vitamin E, choline, inositol, selenium and other trace elements in the feed used, phosphorus deficiency or imbalance in the proportion of calcium and phosphorus is also easy to induce liver disease, which is more common in self-ingredients or reasonable formulation of feeds.
3. Chemical drugs cause liver damage in fish. Fish disease control mostly relies on the use of chemical drugs, and frequent indiscriminate drug delivery leads to liver damage in fish.
4. Foreign pollutants cause liver damage in fish. If the pond inlet and drainage is polluted to varying degrees, coupled with the pollution of the culture itself such as hydrogen sulfide, ammonia nitrogen, algal toxins, etc., it will also cause damage to the liver of fish.
Third, how to prevent the occurrence of grass carp liver disease
1. Improve the breeding environment
Pay attention to changes in water sources and pond water bodies, fill new water at any time and use microecological agents to regulate water quality.
2. Take bile acid internally in the mixing ingredients to reduce the burden on the liver and protect the liver and detoxify
Bile acids can improve the activity of lipase, improve the utilization of fat in fish, promote the digestion and absorption of fat, and improve the liver function of grass carp. In addition, bile acids can bind or decompose endotoxins in the intestine, prevent endotoxins from entering the liver, reduce the absorption of endotoxins in the intestines, increase intestinal barrier function, and prevent the harm caused by endotoxins.
3. Reasonable feeding
In the case of unstable weather, the appropriate amount of feeding should be reduced, not blindly pursuing long speed, in order to reduce the digestive burden of the fish body, ensure the health of the fish body, and achieve sustainable growth, while the daily feeding should be scientific feeding, "seven points full", to avoid excessive feeding.