NUTRITIONAL COMPOSITION OF TOASTED SOYBEAN, BLANCHED AND SUN-DRIED DUCKWEED MEALS USED AS PROTEIN SOURCES

Abstract

This study was conducted to compare the nutritive values and antinutrient contents of plant protein sources such
as toasted soybean meal (TSBM), blanched duckweed meal (BDM) and sun-dried duckweed meal (SDM) with the
requirement for Nile tilapia feeding. Determination of all samples was done in triplicate. TSBM had significantly
higher (P≤0.05) protein content (38.00%) while raw duckweed meal (RDM) had the least (35.08%). The total
essential amino acid ranged from 32.77 to 41.11 g/16gN of crude protein and the total essential amino acid to
crude protein content ratio ranged from 102.00 to 128.00 g/16gN. There was a significant difference (P≤0.05) in
the macro mineral concentrations of all the samples except in magnesium which was not significantly different
(P>0.05) in all the treatments. BDM gave the best reduction of antinutrient content by 95.26%, 92.18%, 61.47%,
33.33% and 12.50% for tannin, saponin, alkaloid, oxalate and phytate, respectively. All the nutrients in TSBM,
BDM and SDM are sufficient as regards the nutrient requirement for species like Nile tilapia Oreochromis
niloticus except for methionine which was the only limiting amino acid. Therefore, should these feedstuffs be
considered for inclusion in the diet of such species, DL-methionine supplementation would be required to
maximise production characteristics.