Nutritional composition of shea nut (Vitellaria paradoxa, gaertn) byproducts and their digestibility by Nile tilapia (Oreochromis niloticus L.) juvenile

Abstract

This study was conducted to determine the nutritional (proximate and energy) composition of selected shea nut by-products (SNPs) namely; shea nut meal (SNM, solvent extracted), shea nut cake (SNC, mechanically extracted) and shea nut cake (SNCW, water extracted) and their apparent digestibility coefficient (ADC) by Nile tilapia, Oreochromis niloticus. The ADC was determined using a reference diet with chromic oxide indicator and test diets that contained 70% reference diet and 30% of SNPs being evaluated. Nile tilapia (26.89 ± 3.19 g) was stocked in rearing tanks at 12 per tank and their faeces was collected from two replicate groups of fish by siphoning. Crude protein (CP), crude lipid (CL), crude fibre (CF) and gross energy (GE) of SNM, SNC and SNCW were 159.8, 70.0, 86.6 g.kg^-1 and 17.4 kJ.g^-1; 145.3, 243.2, 49.3 g.kg^-1 and 21.7 kJ.g^-1; 125.5, 304.0, 48.8 g.kg^-1 and 22.9 kJ.g^-1, respectively. The ADC of dry matter (DM), CP, CL and GE of ingredients ranged from 73.0 – 83.8%, 47.3 – 72.0%, 74.7 - 98.9% and 61.2 - 96.3%, respectively. The SNC and SNCW had significantly higher DM, CP, CL and GE digestibility (P < 0.05) compare to SNM. Generally, protein composition and digestibility of the SNPs in this study were low and seem unsuitable as protein sources for Nile tilapia.

Keywords: Nutritional composition, digestibility, nile tilapia, shea nut, by-product