Use of yacon (Smallanthus sonchifolius) juice byproduct as an additive in fish diets: Response of growth performance, antioxidant status, and disease resistance juvenile black rockfish (Sebastes schlegelii) to different feeding strategies

Abstract

Abstract Yacon juice byproduct (YJB) is regarded waste, but it contains bioactive compounds and can be used as an additive in fish feed. This study evaluated the effects of feeding strategy of YJB on the growth performance, digestive and antioxidant capacity, and disease resistance of rockfish. 480 juvenile rockfish (15.5 ± 0.01 g) were distributed into tanks. Four different YJB feeding strategies were evaluated in triplicate: feeding with the basal diet continuously (control, T0), feeding with YJB continuously (T1), feeding with YJB for 1 day and the basal diet for the next day (T2), and feeding with YJB for 1 day and the basal diet for the following 2 days (T3). At the end of 8 week feeding experiment, T1 and T2 groups exhibited enhancement in growth performance compared with T0 and T3 groups. Intestinal digestive enzyme activity was higher in T1 and T2 than in T0 and T3. Lysozyme and antioxidant capacity were higher all YJB feeding regimens than the control treatment. The survival rates in all YJB treatment groups after the challenge with Streptococcus iniae were enhanced. In conclusion, offering YJB at day-to-day intervals is recommended to improve growth performance, digestive and antioxidant status, and disease resistance.