Apparent and true availability of amino acids from common feed ingredients for South African abalone (Haliotis midae L.)

Apparent (APD) and true (TPD) protein digestibility and apparent (AAAA) and true (TAAA) amino acid availability of fish meal and plant protein ingredients utilized in the South African animal feed industry (corn gluten meal, soya bean meal, cottonseed meal, sunflower meal, canola meal, peanut meal, lupins and faba beans), incorporated at 450 g kg−1 into single protein diets, were determined with juvenile South African abalone (Haliotis midae). Soya bean meal (96.34%) and lupins (96.51%) presented the highest APD values, with corn gluten meal (76.08%) the lowest value, while values for sunflower meal (92.21%), canola meal (93.94%) and faba beans (93.17%) were above 90%. APD values for cottonseed meal (86.28%) and peanut meal (86.73%) were comparable with that of fish meal (82.94%). A correlation coefficient (r) of 0.99 was found between ADP and mean AAAA. Furthermore, amino acid availabilities were relatively consistent within various feed ingredients. The mean amino acid secretion from a protein-free diet was 19.08 mg 100 g−1 dry diet, resulting in a mean increase of 1.88% units over all feed ingredients when comparing TAAA with AAAA. Calculated APD according to APD coefficients determined with single protein diets underestimated determined APD in several compound diets by 1.10–6.50%, while mean AAAA was underestimated by 6.93%.