Aquaculture America 2020

February 9 - 12, 2020

Honolulu, Hawaii

PERFORMANCE OF NILE TILAPIA Oreochromis niloticus FED PRACTICAL DIETS CONTAINING INCREASING LEVELS OF BREWERS GRAINS WITH OR WITHOUT AN ADDED ENZYME COMPLEX

Shawn Coyle*, Chelsea Walling,  Waldemar Rossi and James Tidwell
 
 Kentucky State University
Aquaculture Research Center
 Kentucky State University
 
Frankfort KY 40601
shawn.coyle@kysu.edu
 

Brewers Grains (BG) are the solid residue left after the processing of cereal grains to produce beer. Due to poor digestibility in monogastric animals like fish BG are primarily fed to ruminant livestock .  Inclusion rates of BG in diets for fish rarely  exceed  30% of  the  formulation due to poor utilization. AllzymeTM is a proprietary digestive  enzyme  complex containing live bacteria cultures to aid in gastric fermentation of poorly digestible feedstuffs which may improve utilization of BG in diets for fish .

A feeding trial was conducted to evaluate the effects of adding AllzymeTM  to diets containing increasing levels of BG in diets fed to Nile tilapia ( Oreochromis niloticus ).  Twenty juvenile tilapia (average weight 5.0 g) were stocked into each of thirty- six 76 L aquaria with four aquaria per dietary treatment.  Fish were fed three times daily one of nine randomly assigned experimental diets  with basal formulations  containing  either 0% BG, 27% BG or 54% BG and with AllzymeTM added at either the manufacturers recommended rate (MRR) or at two times the MRR to each basal diet .  The 0% BG diet served as a control and was formulated  after a traditional commercial tilapia diet.  All diets contained 8% fish meal and were formulated to be isocaloric and isonitrogenous. Added BG replaced conventional soybean meal and wheat flour in the formulations.

Water quality variables remained acceptable for tilapia production throughout the trial. Feed acceptance and overall growth was good for all diets with an average of >800% weight gain in six weeks. There was no significant difference (P>0.05) in survival or FCR among treatments which averaged 90% and 1.4 overall, respectively.  The average weight (g) and SGR of fish fed the  control diet 0% BG (54.1 and 1.1, respectively) was statistically  greater than for fish fed the 27% BG diet without enzyme addition (46.4 and 0.93, respectively) and for  fish fed all the 54% BG diets which averaged 44.2 g and SGR of 0.88 overall. The 27% BG diets containing added AllzymeTM achieved similar growth performance as the control diet.

Statistically, a ddition of AllzymeTM did not  significantly improve fish performance over the  performance of the basal formulations; however, the trend was a slight increase in growth performance  of fish when AllzymeTM was added at the MRR,  which  did not increase  further when the inclusion rate was doubled. Addition of AllzymeTM  may provide a growth benefit to feed formulations which include  alternative low nutrient density feed ingredients such as BG; however, under the conditions of this study the magnitude of the benefit was slight.  To further  evaluate the potential benefit of  adding AllzymeTM  in  diets for fish;  additional studies should evaluate different  species and longer durations of feeding.