Optimum level of dietary biotin for growth, feed utilization, and swimming stamina of fingerling lake trout (Salvelinus namaycush)

Abstract

Triplicate lots of fingerling lake trout ( Salvelinus namaycush ) held at 9 C for 20 wk were fed a semipurified basal diet supplemented with 1% spray-dried egg white or d-biotin at concentrations of 0.1, 0.5, 1.0, or 5.0 ppm. Trout fed the basal diet, either alone or with egg white, grew more slowly and converted feed less efficiently ( P < 0.05) than those fed supplemental biotin. Neither the growth rate nor feed conversion differed significantly among the four groups fed supplemental biotin. However, when forced to swim to exhaustion against controlled water currents, trout fed either basal diet, with or without egg white, or 0.1 ppm supplemental biotin, swam a shorter distance ( P < 0.05) than those fed more biotin. Fish fed 0.5 ppm biotin swam as far as those fed 1.0 ppm, but not as far as those fed 5.0 ppm. These results indicate that young lake trout probably need no more than 0.1 ppm biotin for optimum growth and feed conversion, but require from 0.5 to 1.0 ppm for optimum swimming stamina.