51. Effect of Dietary Crude Protein Level on UT-B Expression and Nitrogen Efficiency in Growing Baluchi Male Lambs Fed Low or High Concentrate Diets.
- Author
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Abadi, E. Ibrahimi Khoram, Tahmasebi, A. M., Mesgaran, M. Danesh, Naserian, A. A., and Vakili, A.
- Subjects
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DRY matter in animal nutrition , *FERMENTATION , *FATTY acids , *RUMEN fermentation , *ORGANIC compounds - Abstract
An experiment was carried out to evaluate how interactions between forage to concentrate ratio and dietary crude protein level may alter nitrogen efficiency and UT-B expression in growing Baluchi male lambs. Four Baluchi male lambs [30 ± 2 kg BW] were used in a 4 x 4 latin square design with 28-d periods and a 2 x 2 factorial arrangement of dietary treatments. The treatments fed forage: concentrate [FC; DM basis] ratios of 45:55 low concentrate (LC) or 25:75 high concentrate (HC) with dietary levels of CP of 14 low protein (LP) or 18% high protein (HP) [CP, DM basis]. Dry matter intake increased as dietary concentrate level increased. Treatments, dietary CP content and F: C ratio had significant effect on CP intake. Increasing dietary N content of the diet increased dry matter (DM), crude protein (CP) and organic matter (OM) digestibility. Forage to concentrate ratio had a significant effect on neutral detergent fiber (NDF) and OM digestibility. Treatments had significant effect on the CP, NDF and OM digestibility. There were an interaction between dietary CP content and F: C ratio on the ruminal pH, NH3-N concentration, individual volatile fatty acids (VFA) concentration, acetate: propionate ratio and BUN concentration. Except ruminal pH, all ruminal fermentation and blood metabolite factors were affected by both dietary CP content and F: C ratio in trial. Treatments had significant influence on the NI (g/d) and urinary N excretion (g/d) (% of N intake). Also, both dietary CP content and F: C ratio had significant effect on NI. The lambs consume high crude protein treatments tended to have greater urinary N excretion (g/d) than those consume low crude protein treatments. The F: C ratio had a significant effect on urinary N excretion (g/d). Approximately 6.56 times more UT-B was expressed by the rumen ventral sac for lambs on the treatments contain 18% crude protein relative to those on the treatments contain 14% crude protein. In conclusion this study shows that changes in characteristic of the diet produce significant changes in UT-B urea transporter expression within the ovine rumen. Changing urea entry into the GIT via dietary regulation of UT-B could serve as important mechanism to maintenance of nitrogen balance and increase nitrogen efficiency in Baluchi growing lambs. Our findings suggest that the dietary regulation of urea transporters plays a major role in altering urea entry into the gastrointestinal tract. [ABSTRACT FROM AUTHOR]
- Published
- 2015