Growth and Plasma Amino Acid Pattern of Chicks Fed Fish Meal as Sole Source Protein: Effect of Dietary Levels of Chloride, Sulfate, Glutamic Acid and Methionine

Abstract

Two experiments were conducted with chicks fed fish meal as sole source protein from day 1 to day 21 to determine the effect (1) of lowered dietary chloride and sulfate content, (2) of additions of glutamic acid, and (3) of methionine on the growth response and on the plasma free amino acid pattern. These treatments produced characteristic effects on growth and the amino acid concentration in the plasma, indicating complex interactions. Decreasing the chloride and sulfate in a diet containing 12% protein supplied entirely by a fish meal produced a significant positive growth response which was apparently due to the resulting increased availability of arginine and increased concentration in the plasma. Supplementation of glutamic acid (5.05%) to the suboptimal 12% protein diet resulted in an increase in plasma glutamic acid and alanine, but increased growth occurred only when the diet also contained the higher level of chloride and sulfate. The addition of glutamic acid decreased the plasma concentration of threonine, serine, tyrosine, and phenylalanine.Methionine additions failed to increase growth unless glumatic acid was also included in the diet with the lower chloride and sulfate content. The 0.2% methionine supplement with glutamic acid produced a growth response and an increase in plasma methionine, cystathionine, and α-amino butyric acid. When 0.6% methionine was added to the diet, the plasma levels of these three amino acids were higher, resulting in a growth depression. Both levels of methionine supplements in combination with the glutamic acid caused a drop in the plasma lysine, threonine, valine, and histidine.