A Study on the Effects of Tannin-Coated Feed on Grass Carp Intestinal Health and Growth Performance
Release date:
2025-08-01
| As aquaculture scales up and intensive farming models become more widespread, challenges hindering the industry's sustainable development have emerged. Among these, intestinal health issues stand out particularly, becoming a critical bottleneck that limits grass carp growth performance and farming profitability. Under high-density rearing conditions, grass carp are highly susceptible to pathogenic microorganisms such as E. coli and Aeromonas, which can trigger intestinal inflammation. Additionally, deteriorating water quality and inconsistent feed quality further jeopardize the fish’s gut health. To address this, identifying safe, efficient, and eco-friendly feed additives to enhance grass carp intestinal health and boost growth performance has become a critical issue in aquaculture. Tannic acid, a natural polyphenolic compound, possesses notable properties such as antibacterial, antioxidant, and anti-inflammatory effects. It has already been proven effective in regulating gut microbiota and strengthening intestinal barrier function in livestock and poultry farming. However, its application in aquaculture—particularly in grass carp farming—remains in its early stages, and the underlying mechanisms by which it influences grass carp intestinal health and growth performance still require further investigation. |
This study focuses on grass carp, aiming to investigate the effects of tannin coating on intestinal health and growth performance in these fish, while also determining the optimal inclusion level in grass carp feed. The findings will provide scientific evidence and practical guidance for the aquaculture industry.
Materials and Methods
Experimental Design and Grouping
Table 1: Experimental Design
Group Category | Control group | Trial Group 1 | Trial Group 2 |
Normal Control Group | No added tannins | 500g/t Anchangfen M60 | 800 g/t Anchangfen M60 |
Colitis Test Group | No added tannins | 500g/t Anchangfen M60 | 800 g/t Anchangfen M60 |
| Note: Anchangfen M60: Coated with natural plant tannins, with an effective content of ≥40%. Colitis Group: Before the experiment, the animals were fed moldy feed for 15 days; upon dissection, intestinal inflammation was observed. | |||
This study used grass carp as the experimental subjects, which were purchased from a fishery near Guangzhou’s Haigou Island. Six hundred healthy, uniformly sized fish of the current year were selected for the experiment. They were randomly divided into three groups for the normal trial and three groups for the enteritis trial, with five replicates per group—each replicate consisting of 20 fish. During the 63-day experimental period, the fish were fed one of three different formulated grass carp feeds.
Trial address and time: The trial was conducted at the New Hope Seagull Island Aquaculture R&D Demonstration Base in Guangzhou, lasting from September 2024 to November 2024— a total of 63 days.
Test diet: Produced internally by Guangzhou New Hope Company. The trial utilized three types of grass carp compound feed, with Anchangfen M60 provided by Guangdong NanKun Biotechnology Co., Ltd.
Table 2: Analysis of Feed Nutritional Composition
Category | Control group | Trial Group 1 | Trial Group 2 |
Moisture % | 6.56 | 6.51 | 7.41 |
Crude Protein % | 31.42 | 31.25 | 30.86 |
Crude Ash % | 7.74 | 7.76 | 7.63 |
Crude Fat % | 5.74 | 5.63 | 6.15 |
Calcium % | 0.80 | 0.84 | 0.78 |
Total Phosphorus % | 1.28 | 1.30 | 1.27 |
Salt content % | 0.64 | 0.59 | 0.58 |
Aspartic acid | 2.68 | 2.69 | 2.67 |
Threonine | 1.16 | 1.17 | 1.16 |
Serine | 1.35 | 1.37 | 1.36 |
Glutamic acid | 5.69 | 5.71 | 5.67 |
Glycine | 1.48 | 1.5 | 1.49 |
Alanine | 1.51 | 1.57 | 1.48 |
Cystine | 0.05 | 0.18 | 0.14 |
Valine | 1.51 | 1.56 | 1.46 |
Methionine | 0.29 | 0.29 | 0.37 |
Isoleucine | 1.3 | 1.34 | 1.27 |
Leucine | 2.21 | 2.23 | 2.25 |
L-Tyrosine | 1 | 1.02 | 1.01 |
Phenylalanine | 1.4 | 1.41 | 1.39 |
Histidine | 0.84 | 0.82 | 0.83 |
Lysine | 1.9 | 1.93 | 1.93 |
Ammonia | 0.5 | 0.5 | 0.5 |
Arginine | 1.82 | 1.79 | 1.78 |
Proline | 1.68 | 1.6 | 1.66 |
Total | 28.37 | 28.68 | 28.42 |
Note: This data is derived from the testing report provided by the Chengdu Testing Center.
Test measurement indicators: Weight gain rate, specific growth rate, feed conversion ratio, feeding rate, survival rate, and condition factor.
Results and Analysis
The Effect of Tannic Acid on the Growth Performance of Grass Carp
Table 3: Effect of Tannic Acid on Intestinal Health and Growth Performance in the Control Group
Project | Control group | 500 Amp Colon M60 g/t | 800 Ampere-Intestinal Phenol M60 g/t |
Initial tail weight/g | 383.33 ± 6.01 | 379.00 ± 4.30 | 381.25 ± 3.15 |
End-of-life weight/G | 871.67 ± 31.80a | 887.33 ± 6.29a | 953.75 ± 9.65b |
Weight gain rate / % | 127.25 ± 4.73a | 134.20 ± 2.20a | 150.26 ± 4.35b |
Daily Feeding Rate % | 1.91 ± 0.06 | 1.93 ± 0.04 | 1.80 ± 0.01 |
Feed Conversion Ratio | 1.55 ± 0.08b | 1.52 ± 0.03b | 1.33 ± 0.03a |
Specific growth rate % | 1.30 ± 0.03a | 1.35 ± 0.02a | 1.46 ± 0.03b |
Body Fat Percentage | 1.98 ± 0.06 | 1.97 ± 0.04 | 1.99 ± 0.05 |
Back-to-length ratio | 6.85 ± 0.06 | 9.66 ± 2.89 | 7.00 ± 0.12 |
Generosity and Accumulation | 627.08 ± 70.11 | 737.74 ± 29.44 | 764.85 ± 44.76 |
Survival Rate % | 100 ± 0 | 98 ± 2 | 100 ± 0 |
Note: ① Data points in the same column with the same letter superscript indicate no significant difference. P > 0.05), different lowercase letters indicate significant differences P <0.05) Same as in the table below ( P <0.05)
As shown in Table 3, adding Anchangfen M60 to the diet of healthy, normal grass carp significantly improved weight gain, reduced the feed conversion ratio, and enhanced the growth performance of the fish.
Table 4: Effect of Tannic Acid on Intestinal Health and Growth Performance in Grass Carp—Enteritis Test Group
Project | Control group | 500 Amp Colon M60 g/t | 800 Ampere-Intestinal Phenol M60 g/t |
Initial tail weight/g | 450.00 ± 5.00 | 453.33 ± 7.26 | 453.33 ± 7.26 |
End-of-life weight/G | 963.16 ± 19.53 | 862.37 ± 37.48 | 961.67 ± 4.41 |
Weight gain rate / % | 114.18 ± 6.61 | 90.08 ± 5.50 | 112.22 ± 3.00 |
Daily Feeding Rate % | 1.73 ± 0.02 | 1.86 ± 0.07 | 1.70 ± 0.01 |
Feed Conversion Ratio | 1.50 ± 0.06 years | 1.90 ± 0.15b | 1.49 ± 0.02a |
Specific growth rate % | 1.21 ± 0.05 | 1.02 ± 0.05 | 1.20 ± 0.02 |
Body Fat Percentage | 1.84 ± 0.03 | 1.92 ± 0.04 | 1.88 ± 0.05 |
Back-to-length ratio | 7.13 ± 0.05 | 7.02 ± 0.02 | 6.99 ± 0.03 |
Generosity and Accumulation | 814.15 ± 25.22 | 758.75 ± 45.71 | 847.57 ± 40.99 |
Survival Rate % | 98.33 ± 1.67 | 98.33 ± 1.67 | 100.00 ± 0.00 |
As shown in Table 4, when feeding grass carp with enteritis, adding at least 800 g/t of Anchangfen M60 to the diet is necessary to maintain optimal growth performance and improve survival rates.
The Effects of Tannic Acid on Intestinal Health-Related Parameters in Grass Carp
Table 5: Effects of the Normal Test Group on Internal Organ Indices in Grass Carp
Normal Control Group | Control group | 500 Amp Colon M60 g/t | 800 Ampere-Intestinal Phenol M60 g/t |
Dirty Body Ratio | 10.89 ± 9.94 | 10.69 ± 0.21 | 11.42 ± 0.42 |
Liver-to-body ratio % | 1.78 ± 0.15 | 1.73 ± 0.08 | 1.99 ± 0.05 |
Intestinal Elasticity Assessment | 718.75 ± 62.39 | 830 ± 48.99 | 860 ± 53.96 |
Thick intestinal wall | 0.10 ± 0.01 | 0.11 ± 0.00 | 0.11 ± 0.01 |
As shown in Table 5, adding Anchangfen M60 to the diet of healthy, normal grass carp tends to improve their intestinal health.
Table 6: Effects of the Enteritis Test Group on Internal Organ Indices in Grass Carp
Colitis Experimental Group | Control group | 500 Amp Colon M60 g/t | 800 Ampere-Intestinal Phenol M60 g/t |
Dirty Body Ratio | 10.37 ± 0.24 | 9.99 ± 0.60 | 10.71 ± 0.65 |
Liver-to-body ratio % | 1.59 ± 0.20 | 1.63 ± 0.22 | 1.66 ± 0.06 |
Intestinal Elasticity Assessment | 812.5 ± 50.2 | 891.6 ± 29.1 | 883.3 ± 20.8 |
Thick intestinal wall | 0.11 ± 0.00 | 0.11 ± 0.00 | 0.11 ± 0.00 |
As shown in Table 6, adding Anchangfen M60 to the diet of grass carp with enteritis can improve intestinal health in these fish.
Discussion
| Tannins, due to their astringent properties, can effectively enhance intestinal health in animals and alleviate intestinal inflammation. Additionally, tannins exhibit antioxidant activity, offering protective effects on the liver—particularly in aquatic species. Under the conditions of this experiment, when encapsulated tannins were added to the diet of healthy young grass carp, it significantly improved final body weight, weight gain rate, feed intake, feed conversion ratio, and specific growth rate. P <: itemprop="text">(<0.05), and showed a linear correlation with the addition level. The results indicate that adding coated tannins to the diet can improve the viscera-to-body ratio, liver-to-body ratio, intestinal elasticity, and intestinal wall thickness in grass carp, leading to healthier intestines that better facilitate the absorption of dietary nutrients. This, in turn, enhances weight gain and reduces the feed conversion ratio in grass carp. However, for grass carp already suffering from enteritis, the initial impact on their overall health—particularly the impaired secretion of digestive enzymes and reduced digestive capacity due to intestinal inflammation—requires the supplementation of higher doses of coated tannins (800 g/t). Such high doses can positively support the maintenance or recovery of liver and pancreatic functions, gradually improving the health of the fish’s organs and intestines while strengthening the intestinal barrier. Ultimately, this leads to enhanced growth performance and survival rates. In summary, tannic acid exerts a profound influence on grass carp intestinal health, directly linked to their growth performance and overall well-being. Under normal conditions, it promotes the development of the liver and pancreas and safeguards intestinal health. In cases of enteritis, tannic acid significantly boosts gut health by modulating the development of visceral organs and ensuring efficient nutrient accumulation, thereby helping the fish combat inflammation and accelerate recovery. These findings highlight the potential value of tannic acid as a promising tool for both preventing and treating intestinal diseases in grass carp aquaculture. |
Conclusion
| Under the conditions of this experiment, adding 500 g/t Anchangfen M60 or 800 g/t Anchangfen M60 to the diet effectively improved the growth performance, pancreatic health, and intestinal well-being of healthy grass carp, with a linear correlation observed between the supplement levels and these benefits. For grass carp suffering from enteritis, incorporating a high dose of Anchangfen M60 into their diet significantly and progressively enhanced gut health, leading to improved production performance and survival rates. |
Previous entry
Related News
Nacore Biotech, located in Huizhou Shiwan Industrial Park, is a high-tech company specializing in feed additives for livestock, ruminants, aquaculture, and pets—integrating R&D, production, sales, and service.
North Side of Keji North Road, Shiwan Town, Boluo County,Huizhou City, Guangdong Province (No.15)