article · Annals of Animal Science
Flesh pigmentation is a critical factor influencing the market value of farmed fish, which must acquire colouring pigments directly from their feed. This study evaluated the effects of supplementing rainbow trout diets with black mulberry juice powder as a natural pigment source over an eight-week trial. Diets containing four different concentrations of the powder were tested on fish weighing approximately one hundred grams. Trout fed the supplemented diets demonstrated significant dose-dependent improvements in weight gain, specific growth rate, survival, and feed conversion efficiency, with the highest responses observed at the maximum concentration. The supplement also elevated body protein, lipid, and moisture levels whilst reducing blood glucose and liver enzymes. Furthermore, the dietary powder elevated blood carotenoid concentrations and enhanced fillet redness and yellowness while decreasing lightness, confirming benefits for growth, flesh colour, and fish health.
Consumers often evaluate the quality and value of farmed fish based on the colour of the fillet. Because fish cannot synthesise their own pigments, finding effective natural dietary additives is important. Demonstrating that black mulberry powder enhances fillet colouration whilst simultaneously boosting fish growth, feed efficiency, and physiological health provides a potential dual-purpose functional ingredient for commercial aquaculture nutrition.
This research provides applied experimental evidence that black mulberry juice powder could serve as a functional feed additive for rainbow trout producers and aquafeed manufacturers. By simultaneously improving growth metrics, feed conversion, and fillet pigmentation, the ingredient offers commercial appeal. The work represents an applied trial stage, meaning full-scale commercialisation would require industrial feed formulation trials, cost-benefit analyses, and supply chain validation for bulk fruit powder production.
AI-generated from the published abstract. Always read the original work before citing.
Abstract The degree of flesh pigmentation is one of the most important quality criteria dictating the fish market value. It is well known that fish, like other animals, cannot synthesize their own coloring pigments de novo , and must obtain these pigments from their diet. In this study, four levels of black mulberry ( Morus nigra ) juice powder (BMP) as a natural pigment source were incorporated into a basal diet at concentrations of 0, 0.25, 0.5, and 0.75% and fed to rainbow trout weighing 100±5 g for 8 weeks in triplicate. At the end of the feeding trial, the effect of BMP on growth performance, blood biochemical parameters and fillet color was examined. Fish fed BMP showed significant enhancements in weight gain (WG), specific growth (SGR), food conversion ratio (FCR), and survival rates (SR) (P<0.05). SGR, WG and SR values were increased significantly following dietary supplementation with BMP in a dose dependent manner with the highest values in fish fed 0.75%, while the FCR was decreased (P<0.05). Body crude protein, lipid, and moisture contents were increased significantly in fish fed BMP (P<0.05). Dietary BMP has significantly decreased the levels of blood ALT, AST, and glucose (P>0.05). While the blood carotenoid concentration was increased in fish fed 0.5% BMP compared to other treated groups. Fish fed BMP showed increased fillet yellowness ( b* ) and redness ( a* ), while the fillet lightness ( L* ) was decreased when compared to the control (P<0.05). In conclusion, diets supplemented with BMP increased the growth performance, muscle pigmentation, and health status of rainbow trout.
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DOI: 10.2478/aoas-2019-0068
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