Apparent digestibility coefficients of dried or fermented brewer's grains for cultured fish

Objective To determine the apparent digestibility of dry matter, crude protein, crude lipid and crude fiber of dried or fermented brewer's grains in grass carp (Ctenopharyngodon idellus), tilapia (Oreochromis niloticus), yellow catfish (Peltobagrus fulvidraco) and Scortum barcoo.

Method The experimental diets were consisted of 70% basal diet and 30% test feed ingredients, and Cr₂O₃ was added as an exogenous indicator. The fecal samples were collected by siphon after four weeks of feeding.

Result The apparent digestibility coefficients of dried and fermented brewer's grains in different fish were significantly different (P < 0.001). The apparent digestibility coefficients of dried and fermented brewer's grains in grass carp and tilapia were significantly higher compared with those in yellow catfish and Scortum barcoo (P < 0.05). After fermentation, the apparent digestibility coefficients of fermented brewer's grain significantly increased compared to those of dried brewer's grain in four fish species(P < 0.05).

Conclusion Herbivorous and omnivorous fish can utilize the dried brewer's grain better compared with carnivorous fish. The utilization of dried brewer's grain in fish can be improved by fermentation. Fermented brewer's grain can be used in considerable amounts for herbivorous and omnivorous fish, but only in limited amounts for carnivorous fish.