Histological alterations in tryptophan-deficient rainbow trout.

Tryptophan-deficient and nondeficient synthetic amino acid test diets were prepared using D, L-amino acids. The diets were fed to three groups of rainbow trout (Salmo gairdneri) for 8 weeks. Experimental control fish fed well and grew from 1.3 to 2.5 g. Deficient fish fed poorly and did not gain weight. Scoliosis was observed in the deficient fish after 1 week of feeding. Daily transitory scoliosis was noted in some fish. Histological studies of trypthophan-deficient scoliotic fish revealed hyperemia, disorganization of myomere septa, and protrusions of the fibrous matrix sheath, which invests the notochord. Abnormal deposition of calcium was noted in the kidney and the bony plates surrounding the notochord and sheath. Fish with mechanically induced scoliosis had disorganization of myomere septa, but did not have protrusions of fibrous matrix sheath, nor did they have abnormal calcium deposition in bone or kidney. Scoliotic fish returned to normal within 1 week upon replacement of tryptophan in the ration.