Dietary Supplementation With CoQ10 and Sel-Plex Mitigates the Effects of Elevated Water Temperature on Performance, Digestive Physiology, Immune Competence, and Antioxidant Balance in Rainbow Trout.

Abstract

Background/aims: Elevated water temperatures can impair fish growth, immunity, and physiological performance. This study aimed to evaluate the effects of dietary coenzyme Q10 (CoQ10) and organic selenium (O-Se; Sel-Plex) supplementation on growth, digestive enzymes, innate immunity, antioxidant capacity, and the expression of stress- and immune-related genes (hsp70-α and il-1β) in the liver of rainbow trout (Oncorhynchus mykiss) under thermal stress, measured using real-time quantitative PCR (RT-qPCR) with β-actin as the reference gene.

Methods: A total of 225 rainbow trout (21 ± 0.5 g) were stocked in 150-L recirculating tanks at either optimal (15°C) or elevated (20°C) water temperatures. Fish were fed diets supplemented with CoQ10 (0 or 20 mg/kg) and/or Sel-Plex (0 or 5 mg/kg) for 60 days. Growth indices, digestive enzyme activity, hepatic antioxidant capacity, immune parameters, and the expression of hsp70-α and il-1β were assessed.

Results: Elevated temperature significantly reduced growth, feed efficiency, and immune status. Dietary supplementation with CoQ10 or O-Se improved hepatic antioxidant capacity, digestive enzyme activity, and innate immunity, with the greatest effects observed when both supplements were combined. Cosupplementation also mitigated heat-induced upregulation of HSP70-α and IL-1β and reduced liver malondialdehyde (MDA) levels.

Conclusion: Combined dietary CoQ10 and O-Se supplementation alleviate the adverse effects of elevated water temperatures on rainbow trout by enhancing growth, physiological performance, antioxidant defenses, and immune responses.