Effects of Inulin and Mannan-oligosaccharide on growth, feed utilization, fatty acid profiles, and intestinal morphology of Chamo strain Nile tilapia (Oreochromis niloticus) fry reared under suboptimal temperature

Abstract

The effects of inulin and mannan-oligosaccharide (MOS) on growth, feed utilization, fatty acid profiles, and intestinal morphology of Chamo strain Nile tilapia (Oreochromis niloticus) fry reared at suboptimal temperature were investigated in this study. Chamo strain Nile tilapia is a local strain in Ethiopia that has been selected for fast growth and disease resistance under tropical conditions. However, its performance under cold stress or sub-optimal temperature is unknown. Four experimental diets were formulated to contain 0% (control), 5 g kg^-1 inulin, 6 g kg^-1MOS and a combination of 2.5 g kg^-1 inulin and 3 g kg^-1 MOS. Each diet was fed to triplicate groups of Nile tilapia fry (initial weight 1.6 ± 0.074 g) for nine weeks at a suboptimal temperature of 22.88 ± 0.48 ^oC. The results showed that prebiotic supplementation did not significantly affect the survival, final weight, weight gain, SGR, FCR and ash content of the fish except for the slight improvements observed with MOS alone and in combination with inulin. However, MOS alone or a combination with inulin improved the villi length and width, and some PUFA levels of the fish compared to the control group. The fish fed with the combination of inulin and MOS had the highest crude lipid content and villi length in the proximal and middle intestine among all groups. The fish fed with MOS alone had the highest villi width and some PUFA levels among all groups. These results suggest additions of these prebiotics have improved the villi length and width, and some PUFA levels of Chamo strain Nile tilapia and could be used as sustainable additive in tilapia nutrition under suboptimal temperature conditions Therefore; further studies are needed to optimize the prebiotic supplementation for Nile tilapia under different conditions.