Taurine: An Indispensable Ingredient in the Development of Sustainable Aquafeeds
Watson, Aaron Mackenzie
Place, Allen R.
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Aquaculture as a global industry is at a crossroad; increased production cannot rely on the unsustainable harvest of forage fish for feed production. The use of fishmeal and fish oil as components in feeds for aquaculture, most notably for high value marine carnivores must be reduced or eliminated. The most promising and sustainable sources of replacement feed must be plant derived, such as soybean meal, wheat flour, and corn gluten along with dozens of other plant derived sources. Likewise for fish oil the most promising sources are plant oils such as soybean and canola oil supplemented with necessary omega-3 fatty acids. This work was undertaken to examine the effects of switching marine carnivores from fishmeal-based feeds to fishmeal-free, plant-based diets. The majority of this research has been conducted with cobia, Rachycentron canadum, a promising species for intensive aquaculture due to its rapid growth rates, high disease resistance, and lack of a major commercial fishery as competition. A variety of plant proteins, plant protein blends and alternative lipid sources were examined for digestibility and efficacy as fishmeal replacement sources in regards to their effects on growth rates, feed conversion, and a range of physiological characteristics. This work has explored the hypothesis that marine carnivores have lost the ability to synthesize taurine, a non-protein amino acid, in sufficient quantities and must therefore be supplied through the diet, and should be considered essential for all marine carnivores. By measurement of gene expression of the genes in taurine biosynthesis, this work shows that cobia do not possess the ability to regulate taurine biosynthesis confirming taurine must be supplied through the diet. Overall, this work has developed multiple plant protein-based feeds that perform equivalently or better than commercial and commercial-like diets. Taurine has been shown to be an essential ingredient when seeking to reduce or preferably, eliminate fishmeal and thereby making aquaculture sustainable in providing protein to meet the world's growing population.