Species that feed at the lowest level of the food chain, such as cyprinids (carps), are often recommended for sustainable aquaculture. However, the gastrointestinal biology of carps has limited their acid-peptic digestion, acid lysis of plants and invertebrate tissues, and phosphorus absorption.
Moreover, intensive carp farming induces stress in the fish, leading to high susceptibility to various pathogens such as fungi, bacteria, viruses, and parasites, thereby affecting the profitability of aquaculture operations.
In this regard, carp farmers require techniques to reduce mortality rates and increase production, which are important for ensuring successful carp aquaculture. One of these techniques is the use of feed additives.
Researchers from the Institute of Aquaculture and Protection of Waters at the University of South Bohemia in České Budějovice published a scientific review on the use of plant-origin food additives (PFA) in Cyprinus carpio (common carp).
According to the researchers, most of the research on plant-origin food additives in carp focuses on improving the efficiency of food and nutrient utilization across various levels, while the other half focuses on ensuring animal welfare standards.
Plant-Origin Food Additives
The European Commission defines feed additives as “products used in animal nutrition to improve the quality of feeds and the quality of animal-derived food, or to improve the performance and health of animals by enhancing the digestibility of feed materials.”
In this sense, food additives can enhance the digestibility of non-traditional food ingredients and promote their conversion into food or flesh.
Plant-origin food additives include essential oils (EO), plant part extracts (PPE), medicinal plants (herbs), and spices. These additives have been widely used in common carp aquaculture research to improve food and nutrient utilization.
However, it has also been reported that some plant-origin food additives reduce carp growth or have no impact on fish health.
Food Additives Used in Common Carp
The researchers report that plant parts such as leaves, roots, barks, branches/stems, fruits, and flowers have been used as additives due to their content of terpenes and phenols.
However, they emphasize that some additives contain undesirable compounds such as saponins, tannins, and alkaloids, which are antinutrients and could be harmful to fish in high doses.
“The chemical composition of plants and their associated bioactivities depend on various factors, such as geography, season, and maturity stage,” they report, highlighting that this information is necessary to understand the mechanisms of additives and the repeatability of experiments.
Factors Influencing the Performance of Additives
The effects of additives depend on factors such as bioactive components, administration method, dosage, timing, and the physiological conditions of the fish.
“According to the results of principal component analysis (PCA), the main factors influencing the performance of additives are the inclusion percentage of the additive, fish age/size, population density, experiment duration, and feed ration,” they report.
Inclusion Rates
According to the study, the effective inclusion rate for essential oils is 0.5 – 0.75%.
On the other hand, plant part extracts (PPE), herbs, and spices work with a generic inclusion rate of 2% to 5% in carp feed.
Plant Species
In carp, dietary supplementation (0.1% and 0.2%) of dill (Anethum graveolens) suppressed growth, while garden cress (Lepidium sativum) improved growth at the same inclusion rate.
Some plants like oak (Quercus aegilops), ginger, lemon (Citrus limon), asafoetida (F. asafoetida), and lamb’s quarters (Chenopodium album) improved carp growth by ≥100% compared to the control, depending on the inclusion percentage.
On the other hand, plants like pistachio (Pistacia vera), common mallow, bayleaf cistus, and pepper-rosemallow (L. sidoides) can reduce carp growth beyond −20% depending on the inclusion rate.
Conclusion
“The use of plant-origin food additives in the diet of Cyprinus carpio is a promising approach to enhance food and nutrient utilization, leading to improved growth and immunity,” concluded the researchers.
They established trends in the use of plant-origin food additives in the diet of C. carpio and identified some factors influencing their effectiveness.
“While it has been demonstrated that PFA, such as essential oils, plant extracts, medicinal plants, and spices, are effective in improving growth and immunity, it is essential to note that not all PFA have a positive influence, and some may even have negative effects,” they conclude.
The researchers recommend establishing a threshold for the inclusion of PFA in the diet of C. carpio to maximize their benefits and minimize potential risks.
Contact
Jan Mraz
Institute of Aquaculture and Protection of Waters
Faculty of Fisheries and Protection of Waters, University of South Bohemia in České Budějovice
Na Sadkach 1780, České Budějovice 370 05, Czech Republic.
Email: jmraz@frov.jcu.cz
Reference (open access)
Kuebutornye, FKA, Roy, K, Folorunso, EA, Mraz, J. Plant-based feed additives in Cyprinus carpio aquaculture. Rev Aquac. 2023; 1- 28. doi:10.1111/raq.12840
