Ashbell, G., Agricultural Research Organization, The Volcani Centre, Bet Dagan, 50-250, Israel
Theune, H.H., Institute of Grassland and Forage Research, Federal Research Centre of Agriculture (F.A.L.), Braunschweig, Germany
Sklan, D., Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, 76-100, Israel

Changes in amino acid fractions of chopped low‐to‐medium protein whole‐crop wheat were studied at four stages of maturation and at two stages after a 24 h wilting period. Tests were carried out after an ensiling period of 90 days, and after a further 7‐day post‐fermentation aerobic exposure. Total amino acids contents in the dry matter during the fermentation period remained stable. Quantities of essential amino acids decreased during maturation and fermentation and remained stable during post fermentation aerobic exposure. The highest amino acid concentrations recorded in the fresh material were those of arginine, lysine, glutamic acid, alanine, leucine, glycine and aspartic acid. Free amino acids varied from a low level in the fresh material < 10% of the total amino acids to ca 65% after the aerobic process. Ammonia‐N content increased in the silage and remained relatively stable on post fermentation aerobic exposure. The concentration of all free amino acids increased except arginine and glutamine during the ensiling period and post fermentation aerobic exposure. After wilting, an increase in free amino acids and a decrease in insoluble amino acids was recorded. The changes in concentration of 18 amino acids during ensilage and following post fermentation aerobic exposure are given. Copyright © 1983 John Wiley & Sons, Ltd