Feed accounts for up to 70% production costs in aquaculture. The increase in the use of vegetable and other alternative protein sources, together with the recent aquafeed price increases of up to 30%, calls for the further innovation in lower cost ingredients. However, the optimal nutritional value of the feed should be maintained, and the use of dietary enzymes in aquafeeds have potential to improve the nutritional value of the feed as well as contributing to the sustainable development of aquaculture.
Accordingly, the hunt for new raw materials of sufficient quality and affordable price is very challenging across aquaculture species and their growing conditions. In addition, stakeholder concerns are not limited to the nutritional value of individual raw materials but also include important factors such as sustainability, welfare, and the effect on the environment A reminder on the benefits of available enzymes to support aquaculture as it grows sustainably is of major interest.
Data from trials with phytases, proteases and enzymes improving the digestion of non-starch polysaccharides, have shown to have significant effects in the performance of the species, the cost of the feed and reduction in phosphorous excretion for example (salmonids, warm water species, Mediterranean species, and shrimp).
A few recent studies show that the use of phytase enzymes (release the phosphorus contained in phytate form in the vegetable ingredients: Phytate P) impact the digestibility and absorption of phosphorus, other minerals and protein. The effect of phytase on the phytate-P, which is poorly digested by animals and is also an antinutritional factor, can improve growth performance in fish species up to 5% because of an increase in phosphorus digestibility up to 65% in rainbow trout and 60% in tilapia. At the same time, these studies demonstrated a reduction in environmental emissions of phosphorous.
Proteases are a key tool to improve the digestibility of ‘low value’ ingredients, increasing the flexibility of the raw material basket: protease inclusion in shrimp and tilapia feeds can maintain animal’s performance with a significant decrease on the use of marine proteins or soy protein concentrates, contributing to control the costs of the feeds and reducing the feed and farm footprints.
Studies demonstrate that the in-feed inclusion of a combination of enzymes, such as phytase, protease and xylanase, can improve energy utilization up to 8% in tilapia when modern formulas are used.
This paper will review the existing data in the use of enzymes in aquaculture feeds, as well identifying current gaps and future needs to support the sustainable growth of aquaculture.