The effect of black glutinous rice bran (Oryza sativa L.) in diets of Nile tilapia (Oreochromis niloticus)

Abstract

The effect of black glutinous rice bran inclusion used in diets of Nile tilapia was studied in fish with an initial weight of 8.76±0.17g per fish and fed with experimental diets supplemented with black glutinous rice bran at 0 (control), 50, 100, 150 and 200 g kg-1 for 60 days. The results of phytochemical analyses of black rice bran showed that the total anthocyanin, phenolic, tannin and phytic acid contents were 52.42±0.23, 3.77±0.03, 0.32±0.13, 0.14±0.01 mg/100g, respectively. The properties of black glutinous rice bran acted as an antioxidant, and the inhibitory percentage of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and thiobarbituric acid reactive substances (TBARs) was significantly different (p < /em><0.05) on storage in different conditions of 4 and 25 ºC. Black glutinous rice bran stored at 4 °C showed significantly higher antioxidant activities analyzed by DPPH and TBARs tests (p < /em><0.05). The percentage of digestibility coefficients and protein digestibility in test diets ranged from 75.21-81.95 and 87.37-91.87 (p < /em>>0.05), respectively. The highest average daily gain, specific growth rate and protein efficiency ratio were observed in fish fed with the diet containing 150 and 200 g kg-1 black rice bran (p < /em><0.05). Feed conversion ratio was slightly better in fish fed the diet supplemented with 200 g kg-1 black glutinous rice bran. The serum biochemical values including total protein, albumin, total bilirubin, alkaline phosphatase (ALP), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity were not significantly different in the various experimental groups (p < /em>>0.05). Therefore, supplementation of black glutinous rice bran in tilapia diets at a rate of 200 g kg-1 resulted in better growth and had no adverse effects on digestibility and serum biochemistry.