Effect of Different Levels of Urea and Sulfur on Microbial Protein Synthesis, Nitrogen Retention, Some Blood Metabolites and Nutrients Digestibility in Mehraban Sheep

Effect of Different Levels of Urea and Sulfur on Microbial Protein Synthesis, Nitrogen Retention, Some Blood Metabolites and Nutrients Digestibility in Mehraban SheepZamani, Z., Aliarabi2, H., Tabatabaei3, M. M., Zamani2, P., Saki3, A. A. and Zaboli4, KH.Abstract This study was conducted to evaluate the effect of dietary supplementation of urea and sulfur on microbial protein synthesis, some blood metabolites (urea and glucose), nitrogen retention, and nutrients digestibility in Mehraban sheep. Experiment was organized as 6×4 Uden square design with 3×2 factorial arrangement of treatments. Ingredients of diets were barley grain, soybean meal, urea, elemental sulfur and mineral supplement. Sulfur was supplemented at two levels of 0.13% and 0.2% on DM basis and urea was supplemented in three levels of 0, 0.25% and 0.5% on DM basis. Daily collections of feces and urine were made during the last 7-days of each period. Excreted purine derivatives (allantoin, uric acid and xantine plus hypoxantine) were measured after total urine collection during a digestibility trail to estimate microbial N supply to the duodenum. At the end of each period blood sampling was taken. Results showed that nitrogen retention, microbial nitrogen supplied to the duodenum, purine derivatives and purine absorption increased by simultaneous feeding of urea and sulfur. Plasma glucose levels and apparent digestibility of organic matter and neutral detergent fiber increased at high levels of urea and sulfur. Plasma urea levels decreased at the higher level of sulfur. It can be concluded that best combination of urea and sulfur might be 0.2% sulfur and 0.5% urea.