Introduction
Climate change is increasingly exposing rainbow trout (Oncorhynchus mykiss) to heat stress and hypoxia, compromising performance, survival, and product quality. Nutritional strategies that enhance resilience are therefore critical. To address this challenge, we evaluated the efficacy of krill meal (KM) as a functional feed ingredient in three trials under climate-relevant stress conditions.
Materials and Methods
Three trials were conducted in Turkey, France, and India using juvenile trout fed diets with 2.5–10% KM for 10–12 weeks prior to stress exposure. Fish were challenged with (i) elevated temperature (14°C to 23°C), (ii) hypoxia (<6 mg L-1), and (iii) acute thermal extremes (31°C and 0.2°C). Growth, feed utilisation, survival, digestive enzyme activity, pigmentation, and proteomic responses were assessed.
Results and Discussion
Across all trials, KM inclusion consistently improved feed intake, growth performance, and survival under stress conditions. Enhanced digestive enzyme activity and antioxidant capacity indicated improved metabolic responses. KM also helped maintain fillet pigmentation under hypoxia.
Proteomic analysis revealed upregulation of proteins associated with oxygen transport, antioxidant defence, and immune function, supporting improved physiological adaptation to environmental stress. These responses align with the nutrient profile of KM, which delivers phospholipid-bound omega���3 fatty acids, natural antioxidants, and key micronutrients such as choline that contribute to improved stress resilience.
Conclusion
Krill meal acts as a multi-functional nutritional strategy to enhance resilience in rainbow trout, supporting performance and robustness under climate-related stress conditions.