Protein quality of some Nigerian feedstuffs. II. Biological evaluation of protein quality

Abstract

The protein quality of some Nigerian protein concentrates were studied by conventional protein quality techniques using weanling albino rats of the Wistar Strain.The true digestibility of the concentrates were between 90 and 98% for most of the feedstuffs examined, except the cashew nut scrap kernel meals I and II, (84.6 and 84.3%); the African locust bean seed only (75.9%); the African locust bean seed and pulp (81.6%); and the palm kernel meal (74.2%) which showed significantly lower values than the others.The animal protein sources examined (milk powder, casein, fishmeals and egg) were found to show superior p.e.r., n.p.r., p.r.e., n.p.u. and b.v. values to those observed for the cashew nut samples, African locust bean seed, groundnut and palm kernel meal. Blood meal, however, could not support the growth of rats and showed poor protein quality indices: −2.46, 0.83, 16.1, 18.9 and 19.3 for the p.e.r., n.p.r., p.r.e., n.p.u. and b.v., respectively.The cashew nut scrap kernel meal samples I and II with protein values in the range 0.76 to 1.12, 2.86 to 3.13, 45.7 to 50.1, 41.3 to 46.7 and 48.9 to 55.3 for p.e.r. n.p.r., p.r.e., n.p.u. and b.v., respectively, were poorer compared to the good grade kernel meal with values of 2.01, 4.01, 64.2, 63.0 and 68.6 for p.e.r., n.p.r., p.r.e., n.p.u. and b.v., respectively, probably as a result of more severe heat damage.The African locust bean seed samples could not support the growth of rats, gave negative p.e.r. (−3.19 to −2.54); low n.p.u. and b.v. (19.8 to 20.9 and 22.3 to 23.7). The palm kernel meal, despite its apparent balance of amino acids showed poor protein quality indices: 1.27, 2.62, 42.0, 44.1 and 56.7 for p.e.r., n.p.r., p.r.e., n.p.u. and b.v., respectively, attributable to its high fibre content and a concomitant lowering of the digestibility.