Abstract: Based on a long-term grazing experiment platform established in the Stipa breviflora desert steppe， this study analyzed the dynamic changes in the nutritional quality of two dominant plants Stipa breviflora and Cleistogenes songorica under different grazing intensities and duration. The results indicated that both moderate and heavy grazing significantly reduced the crude protein （CP） content of the both species. Heavy grazing significantly increased the neutral detergent fiber （NDF） content in the both species and significantly reduced the ether extract （EE） content of Cleistogenes songorica， while light grazing significantly reduced the crude ash content of Stipa breviflora. As the grazing season progressed， the CP content of the both species gradually decreased， whereas the ether extract and acid detergent fiber （ADF） contents exhibited an initial increase followed by a decrease. Specifically， the ether extract content of Stipa breviflora and Cleistogenes songorica peaked in August and July， respectively， while the ADF content for both species reached its maximum in July. Furthermore， CP significant negatively correlated with NDF， as well as between ether extract with crude ash. In contrast， NDF and ADF showed a significant positive correlation. These findings provide a scientific basis for improving the utilization efficiency of biological resources in the Stipa breviflora desert steppe of Inner Mongolia and contribute to the sustainable management of grassland ecosystems.

Key words: Grazing capacity, Grazing time, Desert grassland, Forage nutrition

摘要： 本研究基于短花针茅（Stipa breviflora）荒漠草原建立的长期放牧试验平台，分析主要优势植物短花针茅（Stipa breviflora）和无芒隐子草（Cleistogenes songorica）的营养品质随放牧强度和放牧时间的动态变化规律。研究表明，中度放牧和重度放牧均显著降低两物种粗蛋白含量，重度放牧显著增加两物种中性洗涤纤维含量并且显著降低无芒隐子草粗脂肪含量，轻度放牧显著降低短花针茅粗灰分含量。随着放牧时间的延续，两物种粗蛋白含量逐渐降低，粗脂肪和酸性洗涤纤维含量呈现先上升后降低趋势，短花针茅和无芒隐子草粗脂肪含量分别在8月和7月达到最大值，酸性洗涤纤维含量均在7月达到最大值。两物种粗蛋白含量与中性洗涤纤维含量、粗脂肪含量与粗灰分含量均呈显著负相关关系，中性洗涤纤维含量与酸性洗涤纤维含量均呈显著正相关关系。研究结果为提高内蒙古短花针茅荒漠草原生物资源利用效率提供了科学依据，有利于实现草地可持续利用。

关键词: 放牧强度, 放牧时间, 荒漠草原, 牧草营养