Ngoh, Si Yan, Shen, Xueyan, Nankervis, Leo, Chia, Isaiah, and Hua, Katheline (2025) Evaluation of nutritional value and quality of aquafeed ingredients for Malabar snapper (Lutjanus malabaricus). Aquaculture, 600. 742253.

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Abstract

Fish meal is considered the benchmark for aquafeed ingredients, but its finite supply and rising demand necessitate exploring alternative protein sources. This study evaluated the digestible nutrient value and cost-effectiveness of ten protein ingredients for Malabar snapper (Lutjanus malabaricus). Test diets were formulated by replacing 30 % reference diet with test ingredients: wheat gluten (WG), soybean meal (SBM), soy protein concentrate (SPC), corn gluten meal (CGM), poultry feather meal (PFM), squid liver meal (SLM), a single cell protein (SCP), two black soldier fly larvae meals (BSF1 and BSF2), and fish meal (FM) individually. Fish were fed to apparent satiation over 56 days at 29.56 °C. FM supported the highest growth and feed intake among the tested ingredients. Although the digestible essential amino acid profile of SCP resembled FM more closely than the other raw materials tested, it had the second lowest growth rate, similar to PFM's (P > 0.05). SLM, SPC, CGM, SCP and PFM exhibited significantly lower daily feed intake (g day⁻¹) than FM before Day 7. After Day 7, feeding responses of SCP and PFM were negative. Variations in growth performance and initial feeding responses of the tested ingredients could be explained by their positive association with digestible histidine, lysine, and methionine levels. These findings indicated potential palatability issues or nutrient deficits that limited the use of these raw materials at 30 % dietary inclusion level. Growth performance and initial feeding responses of fish are typically evaluated based on the measured outcomes of the whole diet rather than the test ingredient. Specific ingredient productivity values and quality indexes were calculated to evaluate ingredient qualities independently from the reference diet matrix. These indexes enabled the development of a cost-effective index (CEI) to evaluate ingredient qualities coherently for cost-benefit analysis. Among the ingredients investigated, SBM, CGM, and FM were identified as having the greatest cost-benefit potential. The nutritional values of alternative proteins and the CEI established in this study provide insights into ingredient qualities, highlighting the importance of considering the effect of ingredient qualities on cost, feeding response and growth performance when formulating species-specific diets for Malabar snapper.

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