Apparent nutrient digestibility of plant based diets by tilapia rendalli (Boulenger, 1896)

Abstract

This study investigated the digestibility of diets formulated exclusively out of plant sources fed to Tilapia rendalli.The study was conducted at NkhataBay Fisheries Laboratory along Lake Malawi for 21 days. The experiment was laid out in a Completely Randomized Design (CRD) using 30x30x35cm glass aquaria with each of the four experimental isonitrogeous diets containing varying plant sources replicated three times. Juvenile Tilapia rendalli (25.0 ± 1.0 g) were conditioned for 5 days to accept the artificial dry plant feed fed two times a day. Faeces were collected by stripping method using a tube and pipette, preserved in beakers and later analyzed for chemical composition. An indirect method of measuring digestibility was used to calculate the apparent digestibility coefficients (ADCs) of the diets containing 1% Chromic oxide and faeces. Water quality data was measured on daily basis using a spectrophotometer. Data was analyzed using Analysis of variance (ANOVA) at P=0.05 using R- statistical software. Protein digestibility coefficient ranged from 30.82% ± 0.81 to 29.21% ± 0.91. However, apparent digestibility coefficients for gross energy were slightly higher than those of other elements. Results show that nutritional and digestibility value provide a good support for the development of a system of selecting ingredients for inclusion infish diets.