An evaluation on the selenium yeast supplementation in the practical diets of early juvenile sea cucumber ( Apostichopus japonicus ): Growth performance, digestive enzyme activities, immune and antioxidant capacity, and body composition

Abstract

A 45‐day feeding trial was carried out to investigate the effects of dietary selenium yeast (Se‐yeast) on the survival, growth performance, activities of digestive enzymes and antioxidant enzymes, and body composition of early juvenile Apostichopus japonicus. Five isoprotic (15.6%) and isolipic (1.5%) feeds with graded levels of Se‐yeast (0, 0.5, 1.0, 1.5 and 2.0 mg/kg) were formulated and randomly allocated to the early juvenile sea cucumbers (initial weight: 0.11 ± 0.01 g). The results showed that the weight gain rate (WGR) and relative visceral weight ratio (RVW) significantly increased as the Se‐yeast supplementation increased from 0 to 1.0 mg/kg, and then reached a plateau with further increase in Se‐yeast, while survival rate (SR) increased as the supplementation level of Se‐yeast increased, and the lipase and amylase activities first significantly increased as the Se‐yeast increased from 0 to 1.0 mg/kg, and then significantly decreased with the continuous supplementation of Se‐yeast. The antioxidant capacity and nonspecific immunity were significantly elevated by the moderate level (0.5 and 1.0 mg/kg) of Se‐yeast. Besides, the activities of immune‐related enzymes and transcription of antioxidation‐related genes were significantly elevated by the supplementation of Se‐yeast. However, malonaldehyde contents were significantly reduced in the treatments with 0.5 and 1.0 mg/kg Se‐yeast. The selenium content in the body wall of the sea cucumber showed a markedly increasing trend with increasing Se‐yeast supplementation levels. Results above indicated that a moderate level (0.5–1.0 mg/kg) of Se‐yeast enhanced the growth performance, digestive enzyme activities, antioxidant capacity and nonspecific immunity of early juvenile A. japonicus.

Artificial reefs reduce the adverse effects of mud and transport stress on behaviors of the sea cucumber Apostichopus japonicus

“…japonicus (~ 0.8 g). A possible explanation is that small sea cucumbers are particularly sensitive to the adverse environments 21 , 22 . These results collectively suggest that inevitable transport stress further increases the adverse effects on the movement-related behaviors of A .…”