According to the FAO, aquaculture has projected growth to produce nearly 109 million metric tonnes by 2030. The global trend to be more sustainable is paramount in the aquaculture industry and is leading to better use and optimisation of all the ingredients often used in the feed industry.
It is known that phytase enzymes maximise the phosphorus (P) availability in plant-based ingredients and also makes feed ingredients more cost-effective by optimizing the animal's use of the nutrients in raw materials. This is also valid for omnivorous fish species produced and consumed around the world.
Tilapia is the second most cultivated fish in the world, just after carp and ahead of salmon. Production is growing at an estimated 7% annually over the last decade. This growth demands more resources and the sector must be compliant with better and sustainable production. Technical performance focusing on better nutrition is a key area for improvement as well as decreasing P discharged into the environment. Recent studies estimate that as much as 75% of P contained in fish feed used in intensive aquaculture production is excreted into the environment.
OptiPhos® Plus in tilapia
OptiPhos® Plus is the latest generation phytase developed by Huvepharma based on its know-how of enzyme technology. It was developed by screening phytase variant libraries (based on OptiPhos®) for improved thermal stability while keeping other favourable OptiPhos® properties (ideal pH profile, pepsin resistance and fast action). Huvepharma®'s research demonstrates that apart from being the fastest phytase on the market, OptiPhos® Plus secures stability. The product formulation is presented in liquid form for PPLA (post-pelleting liquid application) processes in aquaculture feed.
Our recent research demonstrated that OptiPhos® Plus improves the growth performance in Nile tilapia (Oreochromis niloticus) during a trial completed in a recirculating aquaculture system (RAS). The total duration of the trial was 93 days, starting with juveniles of 13.3 ± 0.80 g. A total of three diets by quintuplicate (five-fold) were evaluated on a total of 450 fish. All diets were produced by extrusion. The trial setup is described in Table 1 and feed composition is shown in Table 2. Fish were fed in three daily meals (09:00. 14:00 and 17:00) ad libitum. Feed was measured and distributed per tank daily to allow accurate recording and to avoid feed wastage during manual feeding.
The measurements recorded were the feed coversion ratio (FCR), protein efficiency ratio (PER, which is the weight gain of the test groups divided by the protein consumed by the test group), specific growth ratio (SGR) and water quality parameters. In addition, health and mortality were monitored daily.
Results
The results showed that, when using OptiPhos® Plus at 1500 FTU/kg feed, fish body weight (FBW), PER and SGR were significantly higher (p < 0.05) than the treatment with monocalcium phosphate (MCP; Table 3). The OptiPhos® Plus treatment group also showed a higher FBW, PER and SGR compared to the negative control group (p < 0.05).
Changes in the body weight (BW) and FCR alongside the complete trial are shown in Figures 1 and 2, respectively.
Assuming that MCP contains 21% available P, we can demonstrate that 11 kg of MCP can be replaced with OptiPhos® Plus included at 300g/tonne. Recently, MCP prices have increased. Considering an average price of €1000/tonne for MCP we can estimate that replacing MCP with OptiPhos® Plus saves about €11/tonne of feed.
Conclusion
After 93 days of experimental feeding, data shows that supplementation with OptiPhos® Plus improved the overall performance criteria of tilapia. The weight achieved with the OptiPhos® Plus treatment is significantly higher than the weight observed for the negative control group as well as the group receiving MCP.
For all the parameters measured in the study, OptiPhos® Plus improved the zootechnical performance of Nile tilapia. The use of OptiPhos® Plus at 1500 FTU/kg can reduce costs of up to €11/tonne of feed produced.
