Torula Yeast in the Diet of Atlantic Salmon Salmo Salar and the Impact on Growth Performance and Gut Microbiome.

Abstract

Atlantic salmon aquaculture is expanding, and with it, the need to find suitable replacements for conventional protein sources used in formulated feeds. Torula yeast (Cyberlindnera jadinii), has been identified as a promising alternative protein for feeds and can be sustainably cultivated from lignocellulosic biomasses. The present study investigates the impact of torula yeast on the growth performance and the gut microbiome of freshwater Atlantic salmon. Both a marine protein base diet and a mixed marine and plant protein base diet were tested, where conventional proteins were replaced with increasing inclusion levels of torula yeast, (0%, 10%, 20%). This study demonstrated that 20% torula yeast can replace fish meal without alteration to growth performance while leading to potential benefits for the gut microbiome by increasing the presence of bacteria positively associated with the host. However, when torula yeast replaced plant meal in a mixed protein diet, results suggest 10% inclusion of yeast produced the best growth performance results and at the highest inclusion level, potentially negative changes were observed in the gut microbial community, such as a decrease in lactic acid bacteria. This study supports the continued investigation of torula yeast for Atlantic salmon as a partial replacement for conventional proteins.