The growth of the aquaculture sector leads to a demand for sustainable feed ingredients. Prebiotics are potential sustainable feed ingredients that can promote the improved performance of aquaculture species without the use of antimicrobials. This study investigated the potential of Azolla pinnata as a candidate prebiotic source. Prebiotic characteristics and dietary effect of commercial diet (CD) with varying pulverised azolla (PA) inclusion was evaluated. Results showed that PA (9.40% moisture) constitutes around 16.1% ash, 22.3% crude fibre, 20.9% crude protein, 1.7% crude fat and 29.6% nitrogen-free extract. Crude xylan and cellulose content of PA were 13.7% and 12.6% dry matter (DM) respectively. Growth of Lactobacillus rhamnosus in PA-supplemented MRS broth remarkably improved after 4 to 6 hours of incubation. Feeding trials results revealed that PA inclusion had no adverse effect on average survival of milkfish fingerlings, albeit significant improvement (p < 0.01) was noted in group fed with 2% PA-replaced CD in terms of the total weight gain (119.9%), specific growth rate (2.62% day–1) and feed efficiency (79.9%). The present study demonstrated the prebiotic activity of PA, as well as its potential use as dietary feed component for improved growth and feed efficiency of cultured milkfish.

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