Effects of feeding frequency on the growth, body composition and SOD, GPX and HSP70 gene expression in Schizothorax wangchiachii

Abstract The present study was designed to investigate the effects of different feeding frequencies on the growth, feed utilization, body composition, and immune and stress responses of Schizothorax wangchiachii to determine the optimal feeding frequency and provide a scientific basis for S. wangchiachii feeding management. Therefore, four feeding frequencies (one, two, three and four times daily) were evaluated in triplicate tanks for eight weeks. The S. wangchiachii fed twice daily had higher final body weights (FBW) and specific growth rate (SGR) values than the fish fed one, three and four meals daily. The feeding rate (FR) increased significantly as the feeding frequency increased; nevertheless, the feed conversion efficiency (FCE) and protein retention efficiency (PRE) values of the fish fed twice daily were higher than those of the fish fed at other frequencies. The fish fed once daily showed higher moisture and lower crude lipid contents than the fish fed at other frequencies. The ash contents decreased significantly as the feeding frequency increased, whereas the crude protein content exhibited the opposite trend. The feeding frequency did not affect the contents of total amino acids, essential amino acids (EAAs) or nonessential amino acids (NEAAs) in the fish body. The expression levels of superoxide dismutase (SOD) and glutathione peroxidase (GPX) in the liver and spleen were not significantly affected by the different feeding frequencies; however, their expression levels in the gills and kidneys first increased and then decreased, with the highest values being observed in the fish fed twice daily. The expression levels of heat shock protein 70 (HSP70) in the gill and kidney were not affected by the feeding frequency, but HSP70 expression was significantly downregulated in the liver and spleen as the feeding frequency increased from one to four times daily. Thus, the optimal feeding frequency for S. wangchiachii is twice daily.