Aquaculture is an important industry for sustainable protein production, supplying nearly half of global seafood demand. However, the industry’s reliance on fishmeal (FM) as a primary protein source presents sustainability and economic challenges. To address these issues, plant-based protein alternatives, particularly soybean meal (SBM), have been widely explored due to their availability and cost-effectiveness. While SBM is cost-effective and widely available, its antinutritional factors (ANFs) impair nutrient absorption, induce soybean meal-induced enteritis (SBMIE), and compromise fish growth and health. SBMIE, characterized by intestinal inflammation and disrupted barrier integrity, mirrors human inflammatory bowel diseases, where pro-inflammatory cytokines like TNF-α activate pathways such as NF-κB, exacerbating inflammation. The liver, another vital organ, is also affected, with SBM diets causing lipid metabolism disruptions, bile acid imbalances, and hepatic vacuolization.
Functional feeds incorporating prebiotics, probiotics, synbiotics, and postbiotics present a promising solution. These additives enhance gut integrity, modulate immune responses, and promote a beneficial microbiota. For instance, beta-glucans and mannan oligosaccharides restore intestinal morphology, boost immune activity, and mitigate SBMIE, while probiotics like Pediococcus acidilactici improve intestinal health and disease resistance. Liver health can also benefit from functional additives such as amino acids, bile acid emulsifiers, and vitamins, which alleviate SBM-induced hepatic damage and improve nutrient utilization.
This review integrates advances in dietary strategies to enhance gut and liver health in salmonids, proposing functional feeds and microbiome engineering as transformative solutions. Improving fish welfare, growth performance, and sustainability addresses key challenges in modern aquaculture. Future research should focus on refining additive formulations, unraveling molecular mechanisms, and conducting long-term evaluations to optimize the benefits of these strategies.