Abstract: The potential for the nutritional improvement of cassava root sieviate by microbial degradation using Aspergillus niger was investigated over a period of ten days. The proximate constituents of the biodegraded CRS were significantly improved (p<0.01) while the fibre constituents were reduced .As the fermentation period increases there was reduction in the crude fiber content of the CRS while the crude protein increased from 20.90 to 73.40%. Biodegraded and undegraded CRS were now incorporated into layers diet for feeding trial. One hundred and fifty laying birds of Nera strain at 48 weeks were divided into five groups and randomly assigned to the diets, each dietary treatment had three replica results indicated that layers fed on control were not (p>0.05) significantly different from those fed biodegraded diet in terms of body weight gain and feed consumption. Hen day production of layers on biodegraded compared favorably with control and were significantly higher than those fed undegraded diets. The metabolizable energy of layers fed biodegraded were significantly lower (p<0.05) than those on control but better than those fed undegraded diet. 10% mortality was recorded for layers on biodegraded possibly due to microbial contamination. It was concluded that biodegradation had favorable impact on the protein ether extract and ash content of CRS but not on performance of the layers.