A MODIFIED MICROTECHNIQUE FOR ESTIMATING PROTEIN AND AMINO-ACID DIGESTIBILITY IN FISH FRY

Fry of rainbow trout (Oncorhynchus my-kiss) were fed four different di ets for 2 weeks. Fry were then individually stripped of feces, and pro tein and amino acid digestibilities were estimated. Digestibilities co uld be accurately estimated from microquantities of the feces. Protein digestibility ranged from 63.7% to 86.0%; amino acid digestibilities ranged from 50.0% for alanine in a diet containing the alga Phormidium bohneri to 96.7% for methionine in a commercial diet. Though the proc edure described is time consuming, it is quite accurate for estimation of amino acids and protein digestibility in fish fry.