The Induction of Specific Dynamic Action in Channel Catfish by Infusion of Essential Amino Acids

Specific dynamic action (SDA) is defined as the increase in O₂ consumption following the ingestion of a meal. This phenomenon has been observed for many years but is still not well understood. It has been suggested, however, that the metabolic cost associated with growth is the prime causative agent of SDA. The purpose of this study was to determine whether SDA could be artificially induced in the channel catfish by infusing an amino acid mixture directly into the bloodstream. The infusion of an essential amino acid (EAA) mixture equivalent to that in the protein of a standard ration (40 g kg⁻¹) resulted in significant increases in O₂ consumption and ammonia excretion. Plasma amino acid concentrations increased in accordance with O₂ consumption and ammonia excretion rates. The infusion of a D-essential amino acid mixture did not cause a significant increase in O₂ consumption or ammonia excretion. The increase in metabolism following EAA infusion was therefore not due to osmotic or physiological stress. Th...