Availability and Utilization of Amino Acids for Growing Pigs

Abstract

Amino acids vary in their susceptibility to processing conditions. For lysine, threonine, methionine and tryptophan, heat induces changes which depress ileal digestibility slightly but result in a substantial proportion of these amino acids apparently being absorbed in an inefficiently utilized form(s). Thus, the ileal digestibility assay is unsuitable for assessing availability in heat-damaged meals. Separate techniques for assessing amino acid avail- ability are needed for these amino acids. In contrast, the branched chain amino acids, isoleucine, leucine and valine, appear less susceptible to the effects of heat. For these amino acids, reduced ileal digestibility appears to be the main cause of reduced availability. Thus, the ileal digestibility assay can be used to estimate amino acid availability. Growth assays with pigs are expensive, time consuming techniques and are only suitable for determining relatively large differences in amino acid availability. More rapid and inexpensive techniques are needed for determining or predicting availability. Such techniques are unlikely to be developed until the biochemical mechanisms underlying the in amino acid availability are better understood. causes of reductions is the use of technology such as NIR An alternative for predicting amino acid availability spectrophotometry. This should have application if the mechanisms of reduced availability of proteins. affect the reflectance characteristics of proteins.