Apparent Digestibility Coefficients of Unfermented and Anaerobically Fermented Palm Kernel Cake By Nile Tilapia (Oreochromis niloticus)

A 42 day trial was conducted to determine the Apparent Digestibility Coefficient (ADC) of palm kernel cake (PKC) by Nile tilapia Oreochromis niloticus . Three diets comprising the reference diet and other two containing unfermented and anaerobically fermented PKC were used for the study. Chromic oxide (Cr₂O₃) served as digestibility marker. Ninety O.niloticus (mean weight 50±5.0g) were acclimated for seven days and ten of each put into nine 15 liter rectangular plastic aquaria containing water. Each diet was randomly assigned to 3 aquaria and fish fed at 5% body weight daily. Feacal samples were collected by siphoning. ADC for the diets were computed from data obtained from analyses of the diets and feacal samples. The results showed that both the ADC crude protein (89.12%) and gross energy (64.0%) for the reference diet were higher and significantly different (p‹0.05) from those of PKC. Similarly both the ADC crude protein (60.73%) and gross energy (61.84%) for the anaerobically fermented PKC were significantly different (p‹0.05) from those of unfermented PKC (48.70% and 53.48% respectively). These values show that fermentation significantly improved the digestibility of PKC by O.niloticus. However, further improvement of PKC for aquafeed  is required.