The Maximum Carbohydrate from Raw Broken Rice to Lipid Ratio in Hybrid Clarias Catfish Diet

Abstract

Five semipurified palletized diets, diets 1, 2, 3, 4 and 5 contained raw broken rice as a carbohydrate source at the inclusion rate of 30.0, 37.0, 45.0, 52.5 and 60.0%, respectively. The diets were used to determine the maximum dietary level of raw broken rice for hybrid Clarias catfish (Clarias macrocephalus x C. gariepinus). All diets were isonitrogenous with 33% protein and were isocaloric with gross energy (GE) of 428-439 Kcal/100g. The GE of each diet was adjusted isocaloricly by balancing the broken rice and squid liver oil-lard mix so that the diets provided carbohydrate to lipid ratios (CHO:L) of 2.54:1, 3.38:1, 6.61:1, 11.23:1, and 20.24:1, respectively. The diets were fed Ad libitum twice daily for 60 days to 22.0 g hybrid Clarias catfish housed within 200-L indoor circular fiberglass tanks. Total dry feed and protein consumption of the fish fed diet 1 was less than those of fish fed diets 2, 3, 4 and 5 (P<0.05). Weight gain of fish fed diets 2, 3, 4 and 5 was not different (P>0.05) but they were superior to that of fish fed diet 1 (P<0.05). Feed efficiency ratio (FE) was poorest for diet 1 and was highest for diet 2 which was also higher than the FE for diet 5 (P<0.05) but not for diets 3 and 4 (P>0.05). Protein efficiency ratio and protein retention showed the same statistical finding as did FE. The body energy retention of fish fed diets 2, 3, and 4 was higher than that of fish fed diets 1 and 5 (P<0.05). Hepatosomatic index of fish fed diet 1 was lower than that of fish fed diet 5, but the inverse finding was observed for liver lipid deposition. The study suggested that a diet for hybrid Clarias catfish with the indicated protein and energy levels could contain up to 50% of native carbohydrate from raw broken rice which is equivalent to 52.5% of raw broken rice by weight, However, the lipid level in such diet should not be less than 4.4% to maintain CHO:L of 11.23:1