Abstract Sorghum stover was ensiled with five levels of urea (0, 2, 4, 6 and 8%) at about 50% moisture level in sealed polythene bags for 0, 15, 30 and 45 days. The crude protein content increased immediately after treatment but slightly decreased after 15 days, remaining almost stable thereafter. The rumen disappearance of crude protein determined by nylon-bag technique was highest in the 8% urea group and it was almost similar after 30 days of ensiling. The ruminal disappearance of fibre fractions significantly increased at 4% urea and 30 days ensiling. Further increase in the urea level and ensiling period did not bring about a tangible increase.