The objective of the experiment was to investigate-and qualify chemical composition of both Bt and non-Bt cotton crop residues (CCR). The in vitro digestibility of each type of CCR was also determined. Week zero represents the period before introduction of animal to graze on Bt-CCR. From each square meter of 14 square meter cotton residues were cut at 10 cm above the ground level. The components of the crop residues in each square meter were separated in to leaves, bolls and tender branches and then weighed freshly and again after drying in an oven at 105 • C for 24hours. The results revealed significant differences in chemical composition of whole residues, in vitro digestibility of dry matter and in vitro digestibility of protein in Bt CCR. Crude protein and ash were higher in all components of Bt CCR and crude fiber was higher in bolls only. The in vitro digestibility showed lower levels in Bt CCR than in non-Bt CCR.