Feed additives and supplements are compounds incorporated into complete diets to improve growth performance, feed utilization ability, immune responses, and final product quality. Functional feed additives may enhance palatability, they may stimulate feed consumption, they can include antimicrobial, antioxidant and immunostimulant properties and can promote the sustainability of aquaculture.
Ralco, a US-based functional ingredient supplier has developed a phytonutrient feed supplement package, ONE CURRENT™, for use in aquaculture feeds. This phytonutrient package contains a proprietary blend of oregano, thyme and cinnamon MICROFUSED® essential oils, ACTIFIBE® prebiotic, and Yucca schidigera. It was designed to be an everyday highly palatable phytonutrient feed additive package that simulates appetite, promotes gut health and supports immune function. It was designed to support aquaculture species to help overcome stress related to transitions, environment and disease pressure. Previous studies in intensively cultured species including Ictalurus punctatus and Litopenaeus vannamei, demonstrated improved gut health, growth performance, and survival and may also have beneficial effects on water quality in such rearing systems. The product had not previously been rigorously evaluated in salmonids.
Accordingly, a feeding trial was conducted by Riverence Holdings R&D (Buhl, ID) to evaluate the response of Rainbow Trout to the phytonutrient package supplemented feed in optimal vs. sub-optimal rearing conditions. Juvenile Rainbow Trout (37 g, ~12 fpp starting weight) were fed a commercially manufactured diet by Rangen/Wilbur-Ellis Nutrition with the phytonutrient package supplementation (0.05%) (test) or without supplementation (control) and reared for 8 weeks under optimal environmental conditions (1st use water: “Phase 1”) followed by an additional 8 weeks of rearing under suboptimal conditions (3rd use water: “Phase 2”). Growth performance did not vary significantly during either phase of the trial; weight gain, FCR, SGR, feed intake and organosomatic indices were within expected ranges for juvenile Rainbow Trout reared in the aforementioned conditions. Both feeds were readily accepted and feeding behavior was aggressive throughout Phase 1 for both treatments. Feeding was expectedly less active during Phase 2, but fish fed the test feed exhibited a significantly more robust feeding response during rearing in sub-optimal conditions when compared to control. Survival during Phase 2 was also significantly improved by feeding the test feed. Under the conditions of this study, dietary supplementation of ONE CURRENT had no adverse effects on growth performance in juvenile Rainbow Trout and helped maintain performance and survival under challenging rearing conditions.