AbstractThe proximate composition, amino acid profile of the protein, mineral and fatty acid constituents of melon seed were studied by chemical analysis, column chromatography for amino acids and gas chromatography for fatty acids. Two hundred and sixteen, male weanling albino rats of the Wistar strain, 28–30 days old and weighing on the average 50–55 g were used in three experiments to study the protein quality of melon seed meals with and without amino acid supplementation. The raw and fried undefatted melon seed meals (RUM and FUM), had crude protein and fat contents of between 31–37 and 54–57, depending on the variety, while the raw and fried defatted meals (RDM and FDM) had 69–78 and 1.1–2.7 respectively. Crude fibre levels were low in all samples. Melon seed contained high amounts of Ca, P, Mg, K, Zn and Fe. The fat comprised the following percentage acids: linoleic (52.3–57.9), oleic (13.6–21.7), palmitic (11.1–18.6), and stearic (13.0–16.8). The fairly high iodine value (113.1–118.7) and saponification number (192.8–194.6) confirmed the unsaturated nature of the melon seed oil. Lysine and methionine were the amino acids in shortest supply while threonine was marginal. The tryptophan content (2.21 g/16 g N) was higher than in most other plant protein sources.In studies with rats, the true digestibility of RUM, FUM, RDM and FDM were similar (range, 91–93) and were comparable to that for soyabean meal (SBM), (91.74), but lower than for whole hen's egg (WHE), (98.8). RDM and FDM had superior protein quality indices compared to RUM and FUM. RUM, RDM, FUM, and FDM had p.e.r., n.p.r., n.p.u. and b.v. of 0.33, 1.53, 41.30 and 46.84; 0.93, 2.58, 49.74 and 52.84; 0.75, 2.02, 44.64 and 48.79; and 1.01, 2.67, 50.12 and 54.18 respectively, which were significantly (P<0.05) inferior to those for SBM and WHE (1.91, 3.89, 61.33 and 65.85; and 4.77, 6.14, 94.86 and 96.94). Feeding FDM at increasing protein levels (10, 15, and 20) resulted in increasing liveweight gains, improved p.e.r. up to 15, but did not significantly alter the n.p.u. and b.v. Amino acid supplementation of 10 protein FDM diet, confirmed that lysine is the most limiting amino acid in melon seed meal for rat growth, followed by methionine and threonine. The levels of tryptophan and isoleucine
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