Effect of Different Dietary Rumen Degradable to Rumen Undegradable Protein Ratio on Nitrogen Efficiency and Urea Transporter-B Expression in Growing Baluchi Male Lambs

An experiment was carried out to evaluate how dietary rumen degradable and rumen undegradable protein level may alter nitrogen efficiency and urea transporter-B expression in growing Baluchi male lambs. Three Baluchi male lambs (30±2 kg BW) were used in a change over design and given 1 of 3 isonitrogenous supplements: 1) high ruminally degradable protein (RDP/RUP 80:20), 2) medium ruminally degradable protein (RDP/RUP 75:25) and 3) low ruminally degradable protein (RDP/RUP 70:30). Treatments had significant effect on Soluble Fraction (P<0.05), Degradable Fraction (P<0.05), Degradation Rate (P<0.05) and Effective Degradability (P<0.05). A significant difference was observed for DM (P<0.05), CP (P<0.05) and NDF (P<0.05) digestibility. The maximum value of NH3-N (P<0.05) and BUN (P<0.05) concentration was measured in HRDP diet followed by MRDP and LRDP diets. Fecal N excretion of LRDP (g/d) (P<0.05) diet was significantly higher than diets MRDP and HRDP. Urinary N excretion of HRDP diet (g/d) (P<0.05) was significantly higher than other diets. A significant difference was observed for ruminal urea transporter-B mRNA expression (P<0.05). In conclusion, this study show that dietary changes in rumen degradable and rumen undegradable protein produce significant changes in urea transporter-B expression within the ovine rumen. Our findings suggest that the dietary regulation of urea transporters plays a major role in altering urea entry into the gastrointestinal tract.