Effect of fungal fermentation with Aspergillus niger and enzyme supplementation on metabolizable energy values of unpeeled cassava root meal for meat-type cockerels

• In vitro fermentation of cassava root meal (CRM) using Aspergillus niger was conducted.
• This was followed by the determination of ME values by cockerels using gavage method.
• Fermentation of CRM resulted in increased amylopectin and phenyl alanine content.
• Fungal fermentation increased ME values of CRM for cockerels.
• Enzyme-supplementation of fermented CRM improved ME values respect to non-fermented CRM.

A preliminary in vitro fermentation of unpeeled cassava root meal (UCRM) using Aspergillus niger was conducted followed by a force-feeding experiment to investigate the effect of fungal fermentation and enzyme supplementation on metabolizable energy values of UCRM for meat-type cockerels. Thirty two (32) cockerels (Ross 308, 10-week-old) were assigned to four treatment groups consisting of 8 birds per treatment laid out in a 2 × 2 factorial arrangement involving fermented or non-fermented UCRM supplemented with or without commercial enzyme. Additional 8 birds were also used for endogenous study. Compositional analysis of the fermented UCRM showed reduced (P < 0.05) dry matter, ash, crude fibre, NDF, ADF, resistant starch, K, Mg, P, increased (P < 0.05) hemicellulose and amylopectin content following fungal fermentation with A. niger. The concentration of glutamine, glycine and proline in fermented UCRM reduced (P < 0.05) while phenyl alanine content increased (P < 0.05) following fungal fermentation. Fungal fermentation improved (P < 0.01) AME, AMEn, TME and TMEn values of UCRM for cockerels. Enzyme supplementation of fermented UCRM resulted in higher (P < 0.01) AME, AMEn, TME and TMEn values than unfermented UCRM. In conclusion, fermentation of UCRM supplemented or not with exogenous enzyme showed prospect for improved metabolizable energy values for cockerels.