Effects of Dietary Yeast (Saccharomyces cerevisia) Supplementation in Practical Diets of Tilapia (Oreochromis niloticus).

A 51-day feeding trial was carried out to determine the effects of various dietary levels of brewer's yeast, Saccharomyces cerevisiae, in the growth performance, body composition and nutrient utilization in Nile tilapia, Oreochromis niloticus, juveniles. Fish (7.6 ± 0.3 g) were stocked into eighteen 1,000-L tanks (100 fish per tank; n = 3) and fed to apparent satiation six isonitrogenous (27% crude protein) and isoenergetic (19 kJ/g) diets, formulated to contain different dried yeast levels (0%, 10%, 15%, 20%, 30% or 40% diet) in substitution to fishmeal. Body weight tripled at the end of the feeding trial for fish fed up to 20% dietary yeast incorporation. Daily growth coefficient (DGC, % body weight/day) decreased with increasing dietary yeast level (P < 0.0001). Voluntary feed intake (VFI, %BW/day) did not vary significantly with increasing yeast level. Fish fed 40% yeast showed significant reduction in protein efficiency rate, protein retention and nitrogen gain. Increasing levels of dietary yeast did not significantly affect protein or lipid digestibility. Dietary dried yeast was seemingly palatable to tilapia juveniles and was suitable up to 15% inclusion to promote growth and efficient diet utilization, without affecting body composition.