Solid state fermentation of barley: crude protein and amino acid digestibility for pigs.

Solid state fermentation of agricultural surpluses or residues is of interest to produce high protein content feed. A simple and non-aseptic solid state fermentation process of barley grain was developed in our laboratory. A cement mixer was adapted as a pilot scale fermentor. Using a selected strain of Aspergillus niger, all the amino acid contents increased after 48 hours of fermentation. However, the amino acid balance was modified (increase of lysine, methionine, cystine, threonine, isoleucine, tyrosine, serine, glycine and alanine part). During the pig experiment, the fermented barley was compared with the initial barley in complete-mixed diets. Except proline, all the amino acids of the fermented barley diet showed higher apparent digestibility. Thus the fermented barley contained more true proteins and the main part of them showed upgraded digestibility.