University of Guilan Animal Production Research 2252-0872 6 4 2018 02 20 Effect of using different sources of nitrogen on digestibility and nitrogen balance in Mehraban male lambs Effect of using different sources of nitrogen on digestibility and nitrogen balance in Mehraban male lambs 27 38 2753 10.22124/ar.2018.7628.1219 FA M. Mahmoudi-Abyane Ph.D student, Department of Animal Science, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran D. Alipour Associate Professor, Department of Animal Science, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran H. R. Moghimi Professor, School of Pharmacy, Shahid Beheshti University of Medical Science, Tehran, Iran Journal Article 2017 05 30 This study was conducted to compare effect of different nitrogen sources on the rate of release, nitrogen balance and nutrient digestibility in Mehraban male lambs. Digestibility parameters and nitrogen balance were measured in 15 Mehraban male lambs. The experiment lasted 21 days including 16 days of adaptation and five days for sample collection. Diets were isonitrogenous and isoenergetic<em>. </em>Diets were included concentrate, mineral and vitamin supplements plus: 1) wheat straw and soybean meal, 2) wheat straw and urea, 3) wheat straw and Optigen^® (a commercial slow-release urea supplement) and 4) wheat straw and slow-release urea produced in laboratory. Before beginning the <em>in vivo</em> experiment, release rate of slow-release urea sources in water and also rumen disappearance was measured. Intake and digestibility of dry matter and organic matter did not affect by treatments, whereas the digestibility of NDF and ADF was significantly different in the treatments containing slow-release urea supplement in comparison of soybean meal treatment (<em>P</em><0.05). The amount of nitrogen excreted in urine was significantly higher in urea treatment while retention of nitrogen in slow release urea diets was significantly lower (<em>P</em><0.05) than other treatments. The results of this study were shown that the slow release urea produced in this study had suitable rate of release in rumen and it could be used in ruminant diets containing low quality forages as a supplement. This study was conducted to compare effect of different nitrogen sources on the rate of release, nitrogen balance and nutrient digestibility in Mehraban male lambs. Digestibility parameters and nitrogen balance were measured in 15 Mehraban male lambs. The experiment lasted 21 days including 16 days of adaptation and five days for sample collection. Diets were isonitrogenous and isoenergetic<em>. </em>Diets were included concentrate, mineral and vitamin supplements plus: 1) wheat straw and soybean meal, 2) wheat straw and urea, 3) wheat straw and Optigen^® (a commercial slow-release urea supplement) and 4) wheat straw and slow-release urea produced in laboratory. Before beginning the <em>in vivo</em> experiment, release rate of slow-release urea sources in water and also rumen disappearance was measured. Intake and digestibility of dry matter and organic matter did not affect by treatments, whereas the digestibility of NDF and ADF was significantly different in the treatments containing slow-release urea supplement in comparison of soybean meal treatment (<em>P</em><0.05). The amount of nitrogen excreted in urine was significantly higher in urea treatment while retention of nitrogen in slow release urea diets was significantly lower (<em>P</em><0.05) than other treatments. The results of this study were shown that the slow release urea produced in this study had suitable rate of release in rumen and it could be used in ruminant diets containing low quality forages as a supplement. https://ar.guilan.ac.ir/article_2753_1d686f471f2241c0262da0100c086179.pdf