Canary seed, Phalaris canariensis, has higher nutritional value than giant kelp seaweed, Macrocystis pyrifera, as feed ingredient in diets for Nile tilapia, Oreochromis niloticus

Abstract

Nonconventional feed ingredients for different aquatic species need to be tested to establish their nutritional value. Thus, this study assessed the use of canary seed (CS), Phalaris canariensis L., and giant kelp seaweed (KS), Macrocystis pyrifera, as ingredients for Nile tilapia, Oreochromis niloticus L., feed. Two feeding trials were conducted: (1) Growth trial, where seven feeds were tested; a control diet (CD) and six CS/KS diets (100, 200, 300 g/kg). Fish fed CS/KS diets (100 and 200 g/kg) had similar weight gain to those fed CD, whereas CS/KS diets (300 g/kg) decreased growth performance (p < 0.05). The CS‐diet Economic Conversion Ratios and KS100 diet were similar to CD, while KS inclusion levels (200, 300 g/kg) decreased this parameter (p < 0.05). Dietary KS inclusion of 300 g/kg significantly decreased the profit index compared with CD and CS‐diets (p < 0.05, 2), digestibility trial, where nine feeds were evaluated: a reference diet (RD); six CS/KS diets (100, 200, 300 g/kg) to determine diet digestibility, and two CS/KS diets (300 g/kg) to determine ingredient digestibility. CS dry matter, protein, and lipid digestibility were higher than KS (p < 0.05). The results suggest that CS has higher nutritional value than KS for Nile tilapia.