In an in vitro and a broiler feeding trial Chinese researchers investigated the effect of fibre-degrading enzymes on the nutritive value of broiler diets containing hulled or dehulled Chinese double-low rapeseed meals.
Enzymes used were xylanase + β-glucanase (A), xylanase (B) and xylanase + cellulase (C). The diets contained 22.5% and 23.5% hulled rapeseed meal or 20% and 21.5% dehulled rapeseed meal.
Overall, in vitro digestibility of dry matter (DM) or neutral digestibility fibre (NDF) did not differ because of meal types.
Both crude protein (CP) and NDF digestibility was improved because of addition of enzymes B or C either to hulled or dehulled diets.
Birds fed dehulled rapeseed meal diets had a higher growth rate, feed efficiency and lower feed intake than those fed hulled rapeseed meal diets during the overall phase.
Enzyme C addition to dehulled diets resulted in improved growth rate and feed efficiency during 4–21 days of age.
Enzymes A and B addition elicited a positive response in feed intake and weight gain, respectively, but did not affect feed efficiency.
The researchers concluded that it would appear that the nutritive value of broiler diets containing Chinese double-low rapeseed meal could be improved by appropriate xylanase-based enzymes.
Responses of broilers to fibre-degrading enzymes could be highlighted by hull removal of fed rapeseed meals.