Interest on non-conventional sources of energy in animal feeding has increased in recent time but these new ingredients still await an adequate nutritional evaluation. Milled dried cassava peel and caged layers' manure mixed in ratio 4:1(w/w), fermented for 7 and 14 days separately and screened for microbial load were used to replace maize in weaner rabbit diets designated as A (0% inclusion of the mixture), B (25%), C (50%), D (75%), E (100%) for 7 days fermentation and F (25%), G (50%), H (75%) and I (100%) for 14 days in a 2 × 4 factorial experiment. Fifty-four weaner rabbits, weighing 620 ± 0.23 g at 7 weeks were randomized into 9 treatments of 3 replicates each (one male and one female rabbit per replicate) and fed for 56 days. Fermentation duration significantly increased (p<0.05) crude protein and decreased crude fibre content in the fermented mixture of cassava peel and caged layers' manure (FCPCLM). Weaner rabbits fed diets A, B and F recorded higher (p<0.05) feed intake than others. Body weight gain, feed conversion ratio and protein efficiency ratio were higher (p<0.05) for rabbits fed diets B and F. Packed cell volume, haemoglobin, and red blood cell counts of rabbits on diets A, B and F were higher (p<0.05) than others. Mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration were also influenced (p<0.05). Aspartate amino transaminase and alanine amino transaminase activities of rabbits fed diets B and F were similar and decreased (p<0.05) as dietary inclusion of FCPCLM increased. Maize can be optimally replaced at 25% in the diet of weaner rabbits by FCPCLM fermented either at 7 or 14 days without adverse effect on their growth performance.