Polyphenol Supplement to Improve Grass Carp Health

Research shows that Polyphenols extracted from apples have the ability to enhance immunity and resist pathogens in grass carp.

Grass carp (Ctenopharyngodon idella) of the family Cyprinidae is a traditional fish with high economic value, delicious and nutritious grass carp meat. To ensure the success of grass carp farming, disease management on grass carp and disease prevention and treatment measures play an important role. Some common diseases on grass carp such as: black head disease, black body disease, scale loss, bleeding on grass carp ... cause many difficulties for farmers. Therefore, studying herbal extracts is an optimal method in prevention and strengthening of fish immunity.

Polyphenol compounds extracted from apples and other plants have powerful antioxidant biological activities, effectively limiting heat stress and oxidative stress in livestock. Many studies prove that Polyphenol supplementation is an effective measure to reduce the harm caused by stress to pets. 

During the rearing process, grass carp have to face many stress triggers such as habitat, immune status, disease, cellular oxidation, etc., all of which adversely affect fish health. farming and crop productivity. In particular, it will weaken immune function, making livestock more susceptible to pathogens, reduce feed intake, reduce growth performance, and even increase mortality. They also affect meat quality, as it can adversely affect the color, elasticity and pH of the meat.

Also read: The Red Earthworm as an Alternative Protein Source in Aquafeeds

Polyphenols extracted from apples have powerful antioxidant biological activities, effectively limiting stress. Photo: pixel2013.

Polyphenols are known to improve antioxidant capacity and inflammatory responses in humans, but their positive response and underlying mechanism have not been clearly established in fish. 

Therefore, a 60-day feeding trial was conducted to explore the effect of apple polyphenols (AP) on improving the health of grass carp. Fish were fed with a vegetable protein diet supplemented with 0, 1, 5 and 10g apple polyphenols/kg feed. 

The results of the study showed that the addition of polyphenols in apples with 5g/kg of feed showed the highest growth rate compared with the other treatments, however, adding polyphenols in apples with the amount of 10g/kg showed the highest growth rate. The growth rate of fish was lower than other groups. 

Dietary inclusion of apple polyphenols exhibited hepatoprotective effects through decreased activity of serum alanine aminotransferase, aspartate aminotransferase and γ-glutamyl transaminase (P < 0.05), and hypocholesterolemic effects. 

Apple polyphenol supplementation improved the high antioxidant status expressed in serum and intestinal tissue antioxidant parameters, followed by a decrease in malondialdehyde content (P < 0.05). 

Antioxidant capacity was improved by apple polyphenols through Nrf2 activation, and overexpression of catalase and copper/zinc superoxide dismutase (P < 0.05). 

Also read: The Endogenous Bacteria Bacillus licheniformis Helps to Boost The Immunity on Grass Carp

Dietary inclusion of apple polyphenols exhibited hepatoprotective effects on grass carp. Photo:  Fisheries and Oceans Canada.

In addition, apple polyphenol supplementation exerts an anti-inflammatory effect through inhibition of the TLR4 signaling pathway, followed by a significant decrease in the transcription of pro-inflammatory cytokines such as IL-1β, IL- 6 and TNF-α (P < 0.05). Thereafter, an enhancement of intestinal barrier function was observed in the apple polyphenols groups of 1g, 5g and 10g in terms of overexpression of junction proteins such as ZO-1, ZO-2, ZO -3 and Occludin (P < 0.05). 

These results suggest that apple polyphenols exhibit beneficial effects on the health of grass carp through improving antioxidant capacity, inhibiting inflammatory responses, and enhancing intestinal barrier function. Overall, the optimal apple polyphenol dosage for grass carp is 5 g/kg diet. Adding Polyphenols in apples helps to save some costs but still maintain or further improve meat quality, helping to increase economic profits for farmers.

Source: tepbac.com