Apparent and true availability of amino acids from common feed ingredients for channel catfish

The apparent and true amino acid availability values for corn, wheat middlings, rice bran, rice mill feed, soybean meal, peanut meal, cottonseed meal, meat and bone meal, and two different samples of menhaden fish meal were determined in adult channel catfish. Although there was reasonable agreement between protein digestibility values and average amino acid availability values, individual amino acid availabilities were variable within and among the various feed ingredients tested. Therefore, we recommended that amino acid availability values should be used for more accurate catfish feed formulation. In addition, it appears that the use of true amino acid availability values should be used for feed ingredients of relatively low protein content.