ASSESSMENT OF NEW YEAST PRODUCTS AS FEED FOR RAINBOW TROUT Oncorhynchus mykiss

Fuel ethanol plants generate a co-product stream known as condensed distillers solubles (CDS). Alternative methods of adding value to CDS were developed by concentrating the nutrients from this stream in the form of the yeast Saccharomyces cerevisiae. The present study began assessment of these novel yeast feed products for aquaculture.

Yeast was produced from CDS by either centrifugation of the spent yeast of ethanol fermentation (Sedicanter) or by propagation of a proprietary strain of yeast grown on CDS (Aerobic); each source was either dried (Untrted) or subjected to a patent-pending process and then dried to produce UltraMax^TM. A 12-week juvenile trout feeding trial was conducted with test diets containing 42% crude protein and 16% crude lipid and various yeast sources included as 20% of the diet.  All diets were hand fed to quadruplicate tanks of trout (initial weight 20 g) to apparent satiation thrice daily.   Fish were group-weighed every 3 weeks to monitor performance. At the end of the trial, all fish were weighed and measured for size distribution curves. Ten fish from each treatment were sampled for biological indices (hepatosomatic index, spleen-somatic index) and histological evaluation (liver, kidney, distal intestine).

Based on the combined data, it is concluded that UltraMax^TM shows significant potential as a rainbow trout and aquaculture feed ingredient.