A study was carried out to evaluate the effect of dietary inclusion of Zymomonas mobilis degraded cassava sifting (ZDCS) on growth response, apparent nutrient digestibility, and ileal digesta viscosity of broiler chickens. Five diets containing undegraded and degraded cassava sifting were formulated to replace wheat offal at 0, 50, and 100% levels. Two hundred and forty (240) one-day-old Marshall broiler chickens were randomly allotted to the five dietary treatments in a completely randomized design (CRD); significant means were separated using Duncan's multiple range test at p < 0.05. The biodegradation of cassava sifting with Zymomonas mobilis significantly increased crude protein content by 44.59% while crude fiber and neutral detergent fiber significantly decreased by 23.08% and 6.38%, respectively. The results showed that birds fed 50% ZDCS had the best (p > 0.05) feed conversion ratio (FCR) at the starter phase. The replacement of wheat offal with 100% ZDCS improved (p < 0.05) the crude fiber digestibility at both starter and finisher phases. Also, the birds fed 100% ZDCS had the lowest (p < 0.05) value of ileal digesta viscosity. The birds fed 50% ZDCS had the highest (p < 0.05) values of gross revenue, gross profit, rate of return on investment, and economic efficiency while the least values for gross profit, rate of return on investment, and economic efficiency were obtained in 100% ZDCS. The study concluded that replacement of wheat offal with 50% ZDCS in the ration of broiler chickens improved FCR, crude fiber digestibility (CFD), and rate of return on investment and economic efficiency.
Keywords: Apparent nutrient digestibility; Cassava sifting; Economy of feed conversion; Growth performance; Ileal digesta viscosity; Zymomonas mobilis.