Grasscutter meat constitutes an important source of much-needed animal protein. The grasscutter (Thryonomys swinderianus) is a wild herbivorous rodent found in the grasslands of Sub-Sahara Africa. It subsists mainly on grass and can digest almost any form of edible greenstuff. Intensive grasscutter production aims at achieving higher levels of DM intake through various vegetative and concentrate supplements to basal diet. The 15 weeks experiment evaluated the performance of twenty four (24) 13 weeks old growing grasscutters, allotted to four treatment groups of six animals each, which were fed diets containing four different fibre sources namely; wheat offal, palm kernel cake, maize sievates and a combination of equal amounts of all the fibre feedstuffs. The experiment involved two replicates per treatment and three growing grasscutters per replicate in a Completely Randomized Design. All the data was subjected to the analysis of variance. The performance of grasscutters, in respect of forage intake, concentrate intake, total feed intake and cost of feeding, was significantly (p<0.05) higher on the maize sievates than on other diets, while the rate of attainment of puberty was significantly (p<0.05) higher on the palm kernel cake than on other diets. These findings suggest that the performance of growing grasscutters was best on the palm kernel cake diet. Palm kernel cake can, therefore, be used as the preferred source of fibre for feeding growing grasscutters.