Siam weed (Chromolaena odorata) meal as digestive enhancer and replacer of DORB in the diet of L. rohita: Effect on growth, digestive enzymes and amylase gene expression

Abstract

A 60-day feeding trial was conducted to evaluate growth response, digestive enzyme activities, digestibility and amylase gene expression of Labeo rohita fingerling fed with Siam weed (Chromolaena odorata) meal (SWM) by gradually replacing de-oiled rice bran (DORB). One hundred and eighty fingerlings were randomly distributed into four distinct experimental groups in triplicates. Four semi-purified iso-nitrogenous diets (330 g kg?1 CP) with different combinations of SWM and DORB such as T1 (diet with 300 g kg?1 DORB + 0.0 g kg?1 SWM), T2 (diet with 200.0 g kg?1 DORB + 100.0 g kg?1 SWM), T3 (diet with 100.0 g kg?1 DORB + 200.0 g kg?1 SWM) and T4 (diet with 0.0 g kg?1 DORB +300.0 g kg?1 SWM) were prepared and fed to satiation level. Among the various groups, T4 showed a significant reduction (p < 0.05) in feed intake than the other experimental groups. T3 group exhibited highest (p < 0.05) WG, SGR, PER compared to T1, T2 and T4 groups. Significantly higher (p < 0.05) amylase, protease, trypsin activities and amylase mRNA expression while lower chymotrypsin activity were recorded in the T3 group compared to the control group. In vitro and in vivo digestibility and metabolic enzyme activities were significantly higher (p < 0.05) for T3 diet fed fish compared to other groups. Overall results revealed that SWM can effectively include up to 300.0 g kg?1 by successfully replacing equal amount of DORB without compromising the growth. Hence, it could be used as an alternate ingredient in the diet of Labeo rohita fingerlings.