Glutamine amino acid supplementation could improve rainbow trout health

Turkey, 11 August 2025 |

Disección de trucha arcoíris

Glutamine, a conditionally essential amino acid involved in protein synthesis, nitrogen transport and intestinal health, emerges as a promising functional feed additive for aquaculture, capable of boosting growth, improving fish health and enhancing fillet quality. Naturally present in protein-rich ingredients of fish feeds, such as fishmeal and plant proteins, it becomes particularly important during periods of stress or high metabolic demand.

Researchers from Aksaray University (Türkiye) tested its effects on female rainbow trout (Oncorhynchus mykiss), a preferred market choice due to their higher fillet yield, healthier lipid profile and superior muscle quality compared to males.

Female are also prone to muscle protein loss during reproductive maturation, making them ideal subjects to evaluate whether dietary glutamine can preserve fillet texture and nutritional value.

Researchers used L-glutamine typically produced through microbial fermentation or plant-based carbohydrates, such as corn or sugarcane, or via enzymatic conversion from glutamic acid. In aquafeeds, the crystalline form allows precise supplementation, supporting muscle development, antioxidant balance and overall physiological performance.

The research, published in Veterinary Medicine and Science, involved 360 female rainbow trout divided into four groups and fed diets containing 0.0%, 0.5%, 1.5% and 2% glutamine for 60 days. Growth performance, blood and biochemical markets, oxidative stress responses and sensory traits of the fillets were evaluated.

Trout fed 1.5 and 2% glutamine achieved higher final weights, weight gain and improved feed conversion ratios. Protein retention increased, while muscle lipid content decreased, resulting in leaner higher-protein fillets.

Blood analysis revealed increased red blood cell count, haemoglobin and haematocrit, indicating better oxygen transport and physiological resilience. In muscle tissue, level of malondialdehyde, a marker of lipid peroxidation, decreased, while antioxidant status improved, suggesting better oxidative balance.

Sensory evaluation showed that while raw attributes were unchanged, cooked fillet from fish fed 1.5% and 2% glutamine had superior texture and flavor, adding potential commercial value.

The study concludes that glutamine could be a novel tool to improve production and product quality in trout farming, though further work is needed to assess cost-effectiveness and long-term application in commercial operations.

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