Digestibility Coefficients of Raw and Processed Lima Bean Diet for Nile Tilapia, Oreochromis niloticus

Abstract

A study was conducted to determine in vivo apparent digestibility of nutrients in raw and processed lima bean diets fed to Nile tilapia, Oreochromis niloticus. All diets were formulated at 30% crude protein level. The control diet contained autoclaved soybean meal. The soybean content of the control diet was replaced with either raw or processed (raw, heated, or autoclaved) lima bean meal. These diets were fed to Nile tilapia fingerlings (18.3±2.4 g) at a stocking rate of 35 fish/tank. The experiment had three replicates. Fish were fed to satiation twice daily. Fecal collection was carried out by hand-stripping the rectal region of fish at four hours after each feeding. Acid insoluble ash was used as an internal marker. Proximate analysis of diets and feces were carried out for crude protein, lipid, crude fiber, energy, and the acid insoluble ash. These were used to calculate the digestibility coefficients of nutrients. Fish fed the raw lima bean diet had the highest fecal nitrogen, while the least was in fish fed lima beans heated for 10 minutes at 204°C. Digestibility coefficients were higher in fish fed the processed lima bean diet than in those fed the raw. The diet heated for 10 minutes had the highest nutrient digestibility coefficients for crude protein, fat, and energy while the diet containing lima beans heated for 15 minutes had the highest crude fiber digestibility coefficient. There were significant differences (P< 0.05) in the digestibility of crude protein, crude fiber, fat, and energy by Nile tilapia fed on the different diets.