This work was carried out to study the effect of green cotton plants by-product and whole corn silage on feed intake, nutrients digestibility, nutritive value, growth performance and economic efficiency of fattening Friesian crossbred calves fed the following experimental rations: Ration1 (T₁) 100 % of nutritional requirements from concentrate feed mixture (CFM) + Rice straw (RS) as control. Ration2 (T₂) 50 % of (CFM + RS) + 50 % of DM whole Corn silage (CS). Ration3 (T₃) 50 % of (CFM + RS) + 50% of DM cotton plants by product silage (CPS).  Ration4 (T₄) 50 % of (CFM + RS) + 50 % of DM (CS + CPS).                 The results showed that, the calves fed T₂ ration which contain wole corn silage and T₄ which contain whole corn silage + cotton plant silage had significantly (P<0.05) improved dry matter intake, nutrient digestibility and nutritive value than ration T₃ which contain cotton plant silage.                 The daily body gain of Friesian crossbred calves  fed rations  T₂ and T₄ significantly (P<0.05) increased than rations control and T₃. Also, feed conversion and economic efficiency of calves took the same trend of daily body gain.                 It showed that, feeding rations containing whole corn silage or whole corn silage + cotton plant silage improved nutrients digestibility, nutritive value, body gain, feed conversion and economic efficiency of Friesian crossbred calves.