Phytogenic Feed Additives in Aquaculture
Plant-based ingredients support the health and productivity of fish and shrimp
Phytogenic feed additives (PFAs), also called botanicals, are plant-based substances that are added to animal diets to improve health and performance. These secondary metabolites have vast potential in terms of biological activities.
Phytogenic feed additives are mixtures of plant-derived secondary metabolites. They are substances that are not important for the primary metabolisms of the plants, but that play a major role for the protection and defense of the plants against environmental and other threats, as well as for attraction purposes like pollination and seed dispersal. These bioactive compounds can beneficially impact the health of fish and shrimp by exerting antioxidant and anti-inflammatory activities. Further, some phytogenic feed additives can also support gut health of aquatic animals through their direct anti-bacterial, anti-fungal and anti-viral properties. These properties explain why phytogenic feed additives play an important role in aquaculture, in addition to their well-known ability to improve digestibility.
Phytogenic feed additives can support gut health of aquatic animals through their direct anti-bacterial, anti-fungal and anti-viral properties.
Challenges in Aquaculture Operations
According to the surveys released at the Global Outlook Aquaculture Leadership Conferences in the last three years, among the four most critical challenges in fish and shrimp production are listed both production costs, with specific reference to feed costs, and diseases. In fact, according to the United Nations’ Food and Agriculture Organization, the cost of the most important ingredients in aqua feeds are constantly increasing. Feed represents 50% to 70% of the production costs and more and more experts are looking into alternatives to be able to reduce feed costs and make the operation still profitable. On the other side the costs of feed, although a huge problem, becomes a minor issue when there are survival losses related to the spread of diseases. A 2014 World Bank estimate attributed approximately US$6 billion of aquaculture losses to diseases. In this scenario every little intervention is important if it can help minimize costs and losses and overcome the productivity gap.
Phytogenic feed additives play an important role in aquaculture by helping to reduce feed costs and support the animal against specific pathogens.
A 2014 World Bank estimate attributed approximately US$6 billion of aquaculture losses to diseases.
Reducing Feed Costs
Feed is the single largest cost item in aquatic production. Fishmeal is decreasing in supply and increasing in price. Consequently, the industry is moving away from this material as a protein source and becoming more dependent on plant proteins. These materials are generally lower in digestibility, higher in amino acid imbalance as well as higher carbohydrate and fiber content. This can negatively affect fish health and growth performance. Phytogenic feed additives can mitigate or reverse these negative effects and hence be a useful tool for fish nutritionists, feed manufacturers and producers to fill the gap between costs and profitability.
Digestarom® P.E.P. MGE has proven to support growth performance in fish in high and low fishmeal diets. The supplementation of Digestarom® in a normal European seabass (D. labrax) diet and a diet with 12.5% reduced fishmeal resulted in numerical improvement of feed conversion ratio when compared to the respective control. Further, the use of Digestarom® in the reduced fishmeal diet could close the feed conversion ratio (FCR) gap between a normal diet and the low fishmeal diet (Figure 1).
Similar results have also been repeated in Nile tilapia (O. niloticus) where normal diets (15% fishmeal inclusion) with and without Digestarom® P.E.P. MGE were compared to low fishmeal diets (5% fishmeal) with and without the product. Improvements in FCR were measured, and the addition of Digestarom® to a low fishmeal diet showed comparable results to the diet with normal fishmeal content (Figure 2).
Phytogenic feed additives in shrimp production
A similar outcome was also seen using phytogenic feed additives in shrimp production. Five isoproteic diets (40% crude protein) but reduced fishmeal levels with or without the addition of Digestarom® P.E.P. MGE were tested. With the use of the phytogenic feed additive the performance gap (measured as FCR) was reduced (Figure 3).
The performance improvements reported here show the importance of phytogenic feed additives when it comes to cost-optimization in aqua diets.
Support Against Pathogens
Major pathogens affecting the aquaculture industry include fungi, viruses, parasites and bacteria. Bacteria can survive very well in aquatic environments, especially when water temperature rises, and can pose major impediments to aquaculture production by causing huge economic losses. Bacteria such as Aeromonas, Flavobacterium, Francisella, Photobacterium, Piscirickettsia, Pseudomonas, Vibrio and Streptococcus have been reported to be pathogenic to aquatic animals. Outbreaks of bacterial diseases are usually contained using antibiotics. However, extensive use of such antimicrobials is linked to the development of antibiotic resistant strains and the transfer of resistant genes between different bacterial species. The emergence of pathogenic resistant bacteria has negative impact not only on aquaculture production but also on human health and consumers perceive fish farming more and more negatively. Therefore, the demand for more environmentally friendly alternatives is higher than ever.
Phytogenic feed additives can have very strong antibacterial effects. Digestarom® P.E.P. MGE proved effective in improving survival rates of Nile tilapia challenged intraperitoneally with Streptococcus agalactiae when compared to a challenged control group (Figure 4). This shows that the product can support the fish by reducing the impact of pathogens.
One of the most important criteria in providing consistent results in the field is the quality of the raw ingredients.
The Digestarom® P.E.P. MGE product line is a science-based solution that combines different essential oils properly selected to improve profitability in production. To provide an efficient solution for aquaculture, where high temperatures and harsh feed production techniques like extrusion are commonly used, the essential oils are delivered through a matrix encapsulation technology that protects them against high temperature conditions and makes sure that the active compounds are released where necessary.
Although new technologies are an advantage when it comes to PFAs, one of the most important criteria in providing consistent results in the field is a good quality of the raw ingredients.
Distillation processes can have different efficiencies in concentrating key compounds and different raw ingredient sources, and different harvest periods may lead to differing concentration of these same compounds.
A mark of reliability for any phytogenic product is to have a standardized formulation and a strong Quality Control (QC) program behind it to insure both consistency and efficacy. Both these characteristics are key to all PFAs produced at BIOMIN.
Gonçalves RA et al. Interactive effects of dietary fishmeal level and plant essential oils supplementation on European sea bass, Dicentrarchus labrax: Growth performance, nutrient utilization, and immunological response. J World Aquacult Soc. 2019; 1–15.