Partial replacement of fishmeal by brewer's yeast (Saccharomyces cerevisiae) in the diets of Thai Panga (Pangasianodon hypophthalmus x Pangasius bocourti)

Feeding trials were carried out to evaluate the efficacy of the replacement of fishmeal with brewer's yeast (Saccharomyces cerevisiae) in the diets of Thai Panga (Pangasianodon hypophthalmus 9 Pangasius bocourti). Thai Panga juveniles with an average initial weight of 36.4 +/- 0.07 g were randomly stocked in cages (1 x 1 x 1.5 m(3)) at a rate of 40 fish per cage. Experimental diets were formulated to provide isonitrogenous (320 g kg(-1) CP) and isocaloric (15.30 kJ g(-1)) diets, by increasing brewer's yeast levels to replace 30%, 45%, 60% or 75% of dietary fishmeal. The control groups were comprised of the commercial feed (CA) and the basal diet without brewer's yeast (CB). Fish were rearing for 9 months. The final weights, weight gains, specific growth rate and daily growth rate showed that brewer's yeast can be used effectively as a substitute for up to 45% of the fishmeal. The replacement of fishmeal by brewer's yeast did not affect the feed efficiency, blood haematology and meat quality (P > 0.05). Alternative complement activity (ACH50), lysozyme activity and total immunoglobulin (Ig) in the fish in groups that had replacement feed diets were significantly higher than those of control group. Replacing 45% of fishmeal with brewer's yeast can improve the growth performance and immune response of the Thai Panga.