This study was conducted in the Shaqlawa Technical Institute of Erbil Polytechnic University in the Kurdistan region of Iraq (from 15/4/2019 till 15/6/2019). It is aimed at determining the effects of using non-urea-treated and urea-treated straw with two levels of nitrogen on the amount of daily feed intake, the weight gain, feed conversion rate and certain blood parameters. 24 Hamdani lambs with an average weight of 24.5 kg and ages of 4 to 6 months were randomly divided into 4 treatments groups: treatment group 1 (T0) without any addition of urea, group 2 (T1) addition of 10% urea, group 3 (T2) addition of 15% urea and group 4 (T4) addition of 20% urea. The results showed all treatments to be non-significant (P≤0.05) for initial weight. For the final weight, the best values were observed in T1 for both low and high levels of non-decomposed nitrogen, in T3 just for a high level of non-decomposed nitrogen. T1 also showed the best value for daily access weight (g). Feed conversion was significant (P≤0.05) in T1, followed by T2, both for high and low levels of non-decomposed nitrogen, respectively. For blood qualities, it was found that T3 and T4 (adding 15% Urea and 20%, respectively) had the most positive effect on blood components.
