Currently, there is a wide variety of commercial aquafeeds for tilapia. A precise evaluation of the suitability of aquafeeds for the particular conditions of a given farm is required to optimize fish feeding and economic feed conversion, while controlling waste emissions. This is highly relevant for optimal fish growth and performance, while ensuring minimal environmental impacts. Monitoring feeding efficiency indicators is very important not only for the economics of feed conversion but also for planning and managing production plans. In this context, it is paramount to develop decision supporting tools for monitoring and forecasting the fish performance as well as nutrient waste. Herein, we illustrate the application of a nutrient-based model (FEEDNETICSTM) to compare two feeds with different protein contents, and at two temperature profiles.
The model was calibrated and validated with success for Nile tilapia (Soares et al. 2023). Data sets related to in vivo experimental trials covering a wide range of rearing and feeding conditions were used. Most of these data sets were collected from the scientific literature, and complemented with some trials run by SPAROS and UTAD (Vila Real, Portugal). Calibrating the model with these data sets means that prior knowledge is being integrated through mathematical functions and made easily available to support new advances in tilapia farming and nutrition.
Simulations were performed for Nile tilapia from 50 to 700 gr, with diets containing 32% crude protein (CP) / 9.4 % crude fat (CF), or 35% CP / 6% CF, both fulfilling all known nutritional requirements of tilapia, and with two annual temperature profiles: 23-31ºC and 20-28ºC. Feeding was according to available feeding tables for the species.
The simulations show a very similar growth performance of the two feeds at 23-31ºC, reaching 700 g in around 164 days, but with the 35/6 diet having a 6 % lower feed conversion ratio (FCR), while the 32/9 show a 0.8% lower economic FCR and a 4% higher nitrogen waste. However, at the 20-28ºC the differences are somewhat augmented: the 32/9 diet show a 1.5% lower economic FCR and a 5.3 % higher nitrogen waste.
In conclusion, we show here that a nutrient-based simulation model can be a useful tool to optimize feeding and control environmental impacts in Nile tilapia. Each farm may choose the most suitable feed to reach its production objectives, under its specific conditions, while evaluating its nutrient emissions.
This work results from activities of projects AquaIMPACT, funded by the European Union’s Horizon 2020 research and innovation program under grant agreement no.818367; and FEEDNETICS 4.0, funded by EUROSTARS-2 program, and by Portugal and the European Union through FEDER/ERDF, CRESC Algarve 2020 and NORTE 2020, in the framework of Portugal 2020 under reference E!12516-FEEDNETICS 4.0_40813.
Soares, F.M.R.C., Nobre A.M.D., Raposo, A.I.G., Mendes, R.C.P., Engrola, S.A.D., Rema, P.J.A.P., Conceição. L.E.C., Silva, T.S. (2023). Development and Application of a Mechanistic Nutrient-Based Model for Precision Fish Farming. J. Mar. Sci. Eng. 11(3), 472. https://doi.org/10.3390/jmse11030472