Feeding of different level of digestible carbohydrate to Pangasianodon hypophthalmus fingerlings: Effect on growth, amylase activity and gene expression.

Abstract

Digestible carbohydrate in fish feed has protein sparing effect and can reduce the protein requirement. In order to evaluate the effect of different carbohydrate level on the growth performance, physiology and amylase expression of striped catfish, Pangasianodon hypophthalmus (Sauvage, 1878) juveniles, a 60 day feeding trial was undertaken. Two purified (isonitrogenous and isolipidogenic) diet with varying digestible carbohydrate level i.e. 20% (T1) and 40% (T2) were prepared and fed to respective groups. Weight gain %, SGR, FER, PER were higher in T2 group. Both the groups showed similar survival rate. In T2, HSI was significantly higher than T1 group. In haematological study, WBC cell numbers declined with the increasing carbohydrate level, whereas RBC and Haemoglobin levels were similar. Amylase activity of both the groups exhibited similar trend as highest activity was recorded on 30th day which decreased gradually. Amylase gene expression also showed similar trend as with enzyme activity, although gene expression were similar after 45 days of feeding. Considering the growth and physiological responses, carbohydrate level in Pangasianodon hypophthalmus diet can be safely increased up to 40%.