Using supplemental amino acids to reduce dietary protein levels of Nile tilapia gives economic and environmental benefits
Amino acids
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by Karthik Masagounder1, Sofia Engrola2, Rita Teodósio2,3, Rita Colen2 and Cláudia Aragão2,3 1 Evonik Nutrition & Care GmbH, Hanau-Wolfgang, Germany 2 Centre of Marine Sciences (CCMAR), Faro, Portugal 3 Universidade do Algarve, Faro, Portugal
quality. However, diet quality is rather determined by the protein orld finfish aquaculture quality and not quantity. production has been This requires additional attention on quantitative and qualitative progressively rising, and amino acid levels. Nile tilapia’s response to dietary protein levels now accounts for almost has been widely studied and is dependent on fish size/age, dietary 47 percent of total fish amino acid profile and digestibility. production. On a global Typically, Nile tilapia starter or fry diets contain 45 percent scale, tilapia are the crude protein, while the diet for fingerlings and advanced second most cultivated juveniles’ optimal growth performance contain 35 percent crude finfish group, with Nile protein. For adults, 25-30 percent protein is commonly used. tilapia (Oreochromis niloticus) accounting for eight percent of Diets with high levels of protein but with an imbalanced amino total finfish produced in 2016. The species is particularly popular acid profile will result in increased amino acid catabolism and due to its fast growing rates, disease resistance, robustness and consequently higher nitrogen losses. ability to adapt to different farming systems. Given the production volume of tilapia and the expected In aquaculture, feed accounts for 50 percent of total production growth of aquaculture as a strategy to feed nine billion people cost. A major challenge is to find new strategies for precision by 2050, it is essential to find diets that are cost effective and diet formulation that minimise feed cost, while increasing environmentally sustainable. sustainability. Feed cost is largely determined by dietary protein We conducted a study to reduce protein inclusion levels in plant sources and inclusion levels. protein based diets for juvenile Nile tilapia, through adequate In the past few years, advances in the knowledge of tilapia amino acid supplementation, in order to minimise dietary nutrition, and commercial availability of supplemental amino environmental impact while maximising biological efficiency. acids have allowed feed producers to be flexible in utilising plant sources to formulate balanced diets. In addition to enabling industry to implement zero fishmeal diets, supplemental amino acids open windows to reduce the dietary protein levels while balancing the diet for amino acid levels. In the swine and poultry industries, the low protein concept with the use of supplemental amino acids has been a common practice for a Figure 1b) Relative 14C-amino acid catabolism and Figure 1a) Daily nitrogen (N) balance in Nile long time. In aquaculture, this relative 14C-amino acid retention in muscle of Nile tilapia juveniles fed the experimental diets for concept is not as common, tilapia juveniles fed experimental diets with different 59 days. Different letters among bars indicate protein levels (D36, D32, D28). Individual value plots and protein quantity is still significant differences (p < .05, ANOVA) and means (black line) per treatment among diets used as an indicator of diet 24 | April 2020 - International Aquafeed