Abstract
TYPPO et al. (1970) and Nordstrom et al. (1970) reported that peak levels of free essential amino acids in the plasma of young swine were reached at 2 to 4 hr. post-feeding. Free essential amino acids in the plasma had attained baseline levels by 8 to 12 hr. postfeeding, except for amino acids that were present in the diet in excess. Some amino acids increased in the plasma during the period from 18 to 36 hr. of fast, apparently as a result of tissue protein catabolism. Patterns for concentrations of isoleucine, leucine, lysine, methionine, threonine and valine in plasma from the portal vein, abdominal aorta, posterior vena cava and jugular vein were similar during the posffeeding period (Nordstrom et al., 1970). With allowance for dilution of blood as it enters the general circulation, removal, of the six amino acids by the liver was indicated by the greater levels of amino acids in the portal vein than the abdominal aorta during the first 6 to 8 hr. post-feeding. Copyright © 1971. American Society of Animal Science . Copyright 1971 by American Society of Animal Science.