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| DOI | 10.1016/j.anifeedsci.2019.01.006 |
| Tibetan sheep require less energy intake than small-tailed Han sheep for N balance when offered a low protein diet | |
| Zhou J.W.; Guo Y.M.; Kang J.P.; Degen A.A.; Titgemeyer E.C.; Jing X.P.; Wang W.J.; Shang Z.H.; Li Z.P.; Yang G.; Long R.J. | |
| 发表日期 | 2019 |
| ISSN | 03778401 |
| 卷号 | 248 |
| 英文摘要 | Tibetan sheep are indigenous to the Qinghai-Tibetan Plateau and graze natural pasture all year round; small-tailed Han sheep were introduced to the plateau, are raised mainly in feedlots and graze natural pasture only in summer. A low energy intake could have a negative effect on N utilization and N balance in ruminants. We hypothesized that Tibetan sheep require less energy for N balance and utilize N more efficiently than Han sheep when offered a low protein and low energy diet. To test this hypothesis, we examined the effect of dietary energy on whole-body N retention and urea kinetics in Tibetan (47.7 ± 2.46 kg BW) and Han (46.2 ± 3.42 kg BW) sheep. Diets were formulated to be low in crude protein (˜7%) with different metabolizable energy levels (6.73, 7.65, 8.57 and 9.49 MJ/kg). Urea kinetics were determined using continuous intrajugular infusion of 15 N 15 N-urea for 72 h. N retention was greater (P < 0.01) in Tibetan than in Han sheep and increased linearly with increasing energy intake (P < 0.001). Tibetan sheep maintained a positive N balance on all dietary energy levels, whereas Han sheep were in a negative N balance at the lowest energy intake. To achieve a N balance of zero, Tibetan sheep required 0.28 MJ/kg 0.75 , whereas Han sheep required 0.33 MJ/kg 0.75 per day. Fecal N excretion was less (P < 0.05) for Tibetan than for Han sheep. Plasma urea concentrations tended to be greater in Tibetan than in Han sheep (P < 0.10), but urinary urea excretion was lower in Tibetan sheep at the lowest energy diet (linear dietary energy × breed; P < 0.05). As energy intake increased, urinary N decreased linearly (P < 0.001) and microbial N production increased linearly (P < 0.001). Urea entry rate and gastrointestinal tract entry rate were greater in Tibetan than in Han sheep (P < 0.01). Urinary purine derivatives excretion, microbial N production, and the portion of microbial N that originated from recycled urea were greater in Tibetan than in Han sheep (P < 0.01). Renal urea reabsorption rate was greater in Tibetan than in Han sheep (P < 0.05) and increased linearly with dietary energy level (P < 0.05). We concluded that: 1) Tibetan sheep were better able to cope with low N diets when energy intake was low; and 2) when N intakes are low, N utilization is improved by supplemental energy. © 2019 |
| 英文关键词 | Dietary energy level; Nitrogen utilization; Qinghai-Tibetan Plateau; Tibetan sheep; Urea recycling |
| URL | https://www2.scopus.com/inward/record.uri?eid=2-s2.0-85059668064&doi=10.1016%2fj.anifeedsci.2019.01.006&partnerID=40&md5=f009b5ea5f41b2eb6da80f590b2f1154 |
| 语种 | 英语 |
| 来源期刊 | Animal Feed Science and Technology
 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 文献类型 | 期刊论文 |
| 条目标识符 | http://gcip.llas.ac.cn/handle/2XKMVOVA/77235 |
| 推荐引用方式 GB/T 7714 | Zhou J.W.； Guo Y.M.； Kang J.P.； Degen A.A.； Titgemeyer E.C.； Jing X.P.； Wang W.J.； Shang Z.H.； Li Z.P.； Yang G.； Long R.J.. Tibetan sheep require less energy intake than small-tailed Han sheep for N balance when offered a low protein diet[J]. 中国科学院西北生态环境资源研究院,2019,248. |
| APA | Zhou J.W.； Guo Y.M.； Kang J.P.； Degen A.A.； Titgemeyer E.C.； Jing X.P.； Wang W.J.； Shang Z.H.； Li Z.P.； Yang G.； Long R.J..(2019).Tibetan sheep require less energy intake than small-tailed Han sheep for N balance when offered a low protein diet.Animal Feed Science and Technology,248. |
| MLA | Zhou J.W.； Guo Y.M.； Kang J.P.； Degen A.A.； Titgemeyer E.C.； Jing X.P.； Wang W.J.； Shang Z.H.； Li Z.P.； Yang G.； Long R.J.."Tibetan sheep require less energy intake than small-tailed Han sheep for N balance when offered a low protein diet".Animal Feed Science and Technology 248(2019). |
| 条目包含的文件 | 条目无相关文件。 | |||||
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