Effects of enzyme addition to canola meal in prawn diets

Enhancement of nutritional value of canola meal by the addition of enzymes was investigated in diets for juvenile Penaeus monodon ((X) over bar +/- SD; 0.96 +/- 0.09 g), with emphasis on liveweight gain and feed conversion ratio (FCR). Six diets were prepared containing either no canola (squid meal based basal diet), basal + 20% canola (low canola diet), low canola + 0.25% enzyme mixture (Porzyme, Finnfeeds International), basal + 64% canola (high canola diet), high canola + 0.25% enzyme mixture or basal + 54% canola + 10% sucrose. All diets were fed ad libitum. Juvenile prawns (three prawns per tank) were fed diets for 42 days with five tank replications per diet. Liveweight gain and feed intake were measured. High canola diet gave significantly lower growth rates (1.79 +/- 0.42 g) (P < 0.05), and enzyme addition increased the liveweight gain from this diet by 28%, to a level similar to the basal (2.33 +/- 0.49 g) (P > 0.05). The low canola + enzyme diet also resulted in higher liveweight gain (2.40 +/- 0.16 g) than the basal and low canola diets (2.29 +/- 0.27 g) but it was not significant. Addition of the enzyme mixture to diets also gave a significant improvement in FCRs. The addition of sucrose to the canola based diet resulted in a significantly higher liveweight gain (high canola + sucrose 2.01 +/- 0.22 g), but did not change the FCR. (C) 1997 Elsevier Science B.V.