Dietary effect of Quillaja saponaria and/or Yucca schidigera extract on growth and survival of common carp Cyprinus carpio, their antioxidant capacity and metabolic response to hypoxic condition

This study evaluated dietary effects of extracts of Quillay Quillaja saponaria, and/or Yucca Yucca schidigera on growth and survival of juvenile common carp Cyprinus carpio, and their antioxidant capacity and metabolic response to low dissolved oxygen (DO) stress. For 8 weeks, fish were fed one of 4 different diets. The diets were supplemented with either 150 mg/kg Quillay (QS), 150 mg/kg Yucca (YS), the combination of 75 mg/kg Quillay and 75 mg/kg Yucca (M), or control diet (C) without addition of Quillay or Yucca. Growth and survival were monitored periodically. After rearing, fish were subjected to low DO stress, and after a week, antioxidant capacity (superoxide dismutase, glutathione peroxidase and glutathione reductase) and metabolic response (glucose, triglycerides and lactate) were analyzed. QSfed fish had the highest weight gain among all the treatments. Treatments did not affect fish survival a week after low DO stress. Among antioxidant capacity and metabolic response, significant effects were found only on superoxide dismutase and glucose. QS fed fish had 39% lower plasma superoxide dismutase than the C and M groups. QS and M groups exhibited 29% and 26% lower plasma glucose than the C group, respectively. Overall, the QS diet improved growth and exhibited favorable antioxidant capacity and metabolic response of carp to low dissolved oxygen environment.