The Role of Glutamine in Growth, Health and Sensory Quality of Female Rainbow Trout (Oncorhynchus mykiss)

Abstract

Objectives: This study aimed to investigate the effects of dietary glutamine supplementation on growth performance, haematological and biochemical responses, oxidative stress parameters and sensory quality of fillets in female rainbow trout. Methodology: A total of 360 female rainbow trout were randomly divided into four groups and fed diets supplemented with 0.0% (control), 0.5%, 1.5% and 2.0% glutamine for 60 days. Growth indices were measured, and blood samples were analysed for haematological and biochemical parameters. Muscle tissue was examined for oxidative stress markers. Sensory evaluation was performed on fillets by trained panellist. Data were analysed using one-way ANOVA and Duncan's multiple comparison test. Results: Glutamine supplementation at 1.5% and 2.0% significantly improved final body weight, weight gain and feed conversion ratio (p < 0.05). Haematological indices, such as red blood cell (RBC), haemoglobin and haematocrit levels, increased in the treated groups. Significant enhancements in total protein and albumin levels were observed, along with reduced malondialdehyde (MDA) levels, indicating improved oxidative status. Sensory evaluation revealed better odour, flavour and texture in fillets from glutamine-supplemented groups, particularly at 1.5% and 2.0% inclusion levels. Conclusions: Dietary glutamine supplementation, particularly at 1.5%–2.0%, enhances growth, physiological health, oxidative balance and sensory characteristics in female rainbow trout. These findings support the practical use of glutamine as a functional feed additive in sustainable aquaculture systems.