A New Choice Of Immune Health For Fish -- Aloe Vera Extract
- Feb 23, 2018 -

8 weeks of 2018

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Intensive aquaculture is becoming a major way to increase fish production and save farming costs, but is prone to widespread outbreaks of fish diseases. Intensive aquaculture also increases fish production and boosts the prevalence of fish diseases. The frequent outbreak of fish diseases and high intensity feeding patterns can not be separated, such as the damage of the low dissolved oxygen and harmful substances in the culture environment to the body organs, and the imbalance of the nutrient ratio in the feed, which will increase the external pressure of the fish, and then affect the immune response of the fish.

There are many ways to prevent the outbreak of fish diseases, including chemotherapy, vaccination, and research and development of products that stimulate the immune system. Among them, the use of antibiotics and chemotherapy can cause corresponding challenges, such as the contamination of drug resistance pathogens and the external environment, and vaccination will produce extra pressure on fish, and the cost is too expensive. In contrast, immunostimulatory stimulation is a relatively mature method. In the selection of potential accelerators of immune system, plant derived substances have attracted much attention. Plant extracts have a wide range of sources, low related costs, widespread inhibition of pathogenic bacteria, and their biodegradability to the environment is relatively small.

The aloe contains phenols, anthraquinones, polysaccharides, trace elements and so on. It can be widely used in medicine, food and beverage, health products, animal feed and other fields. Earlier studies have found that aloe extract has the advantages of cure, anti bacteria, antivirus, antifungal, gastric protection and immune regulation. It has been used in poultry, such as chicken immunity, but its application in aquaculture is still to be dug.

Piaractus mesopotamicus is a freshwater fish native to Brazil. It is also known as the fine scale fat carp, and is the main breed in Latin American countries. The fish is a kind of economic fish with good adaptability, food nature, fast growth, fast growth, strong resistance to disease and delicious meat. It also has a large range of aquaculture in China. A recent study by researchers at the UNESP in Brazil showed that the aloe extract added to the feed could increase the stress response to the outside world and increase the body's immunity. The results are now published in the fish & crustacean immunology magazine.

In this experiment, the researchers divided 240 strips of Scama into 4 different feed schemes, including control group, feed containing 5g kg-1 (0.5%) aloe extract, feed containing 10g kg-1 (1%) aloe extract and feed containing 20g kg-1 (2%) aloe extract for 10 days. On the eleventh day, the researchers sampled the blood of the fish and transported for 4 hours to form pressure stress. After that, the researchers evaluated the fish samples, including LRB, blood glucose levels, hemolytic activity of the complement system, serum lysozyme concentration, and cortisol levels.

Finally, the researchers divided the remaining fish into three groups: no injection, placebo, and Aeromonas hydrophila. After 24 hours of injection, fish samples were collected and tested to assess the plasma sterol, blood glucose level, leucocyte respiratory burst, serum lysis enzyme content, and complement system hemolytic activity. The aloe extract used in this experiment is to remove aloe and its dietary fiber, and add it to feed by spray drying.

The results showed that the plasma cortisol content of fish fed fish containing 1% or 2% aloe extracts after 24 hours of transportation was significantly higher than that in the control group. In the face of disease invasion, the LRB of the control group decreased, but the LRB value of the fish in the aloe extract group increased. Compared with other feeding groups, the concentration of serum lyase in fish with 0.5% and 2% aloe extract increased after 24 hours. Compared with control group and 0.5% aloe vera extract group, SLC increased in 1% and 2% aloe vera extract groups.

In the initial sampling, the hemolytic activity of the fish fed with 2% aloe vera extract feed also decreased. Overall, fish did not die during the whole experiment period. The aloe extract can prevent the loss of the innate immune response of fish, improve the ability of the fish to resist the disease in the process of transportation pressure, and reduce the hemolytic activity of the leucocyte respiration burst and the complement system. At present, the surface aloe extract can be applied in aquaculture, and Chinese herbal medicine in fish feed additives can prevent disease outbreaks.

February 23, 2018