An experiment evaluated forage value of crested wheat grass (CWG) harvested from Western Nebraska over a 2-year period (2019-2020). Two large pastures, comprised of 95% CWG, were divided into 13 paddocks (34.4 ha, 3 paddocks and 42.5 ha, 10 paddocks). Within each pasture, 2 paddocks were assigned at random for sampling. Forage samples were collected twice each month from 2 random locations within assigned paddocks by hand clipping forage within a 0.25m2 quadrant at ground level. For each year, samples were composited by pasture and month. Samples from 2019 (n = 10) were harvested in May, June, July, August, and September while 2020 samples (n = 8) were harvested in May, June, July, and August due to drought conditions. Local precipitation from May 1st to September 30th was 552.7 mm for 2019 and 150.1 mm for 2020 with a 10-yr average precipitation of 350.0 mm. Cattle were stocked at 4.2 hectares per steer using a rotational grazing system. Samples were freeze dried and ground to a 1mm particle size to evaluate in-vitro dry matter disappearance (IVDMD, % of DM), and in-vitro organic matter disappearance (IVOMD, % of OM). Orthogonal contrasts were used to analyze changes in forage quality over time with month and pasture as fixed effects (glimmix procedure of SAS). Forage quality quadratically decreased over the growing season in 2019 (IVDMD, P = 0.02 and IVOMD, P < 0.01). In May, 2019 CWG averaged 54.0% IVDMD and 60.4% IVOMD and decreased to 37.0% IVDMD and 43.3% IVOMD by September 30th. No significant differences in IVDMD (P = 0.57) or IVOMD (P = 0.53) between months were detected for samples collected in 2020 averaging 43.1% IVDMD and 46.8% IVOMD. When precipitation is not limiting CWG, forage quality is greatest early in the growing season and decreases as it matures.

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220 小麦草牧草品质评价

一项实验评估了在 2 年（2019-2020 年）期间从内布拉斯加州西部收获的冠小麦草 (CWG) 的草料价值。两个大牧场，由 95% 的 CWG 组成，分为 13 个围场（34.4 公顷，3 个围场和 42.5 公顷，10 个围场）。在每个牧场内，随机分配 2 个围场进行抽样。每月两次从指定围场内的 2 个随机位置收集草料样本，方法是在地面 0.25 平方米的象限内手工修剪草料。对于每一年，样本按牧场和月份进行组合。由于干旱，2019 年的样本（n = 10）在 5 月、6 月、7 月、8 月和 9 月收获，而 2020 年的样本（n = 8）则在 5 月、6 月、7 月和 8 月收获。5 月 1 日至 9 月 30 日的局地降水量为 552.7 毫米，2019 年和 150 年。2020 年为 1 毫米，10 年平均降水量为 350.0 毫米。使用轮牧系统，每头牛放养 4.2 公顷。将样品冷冻干燥并研磨至 1mm 粒径，以评估体外干物质消失率 (IVDMD, % of DM) 和体外有机物消失率 (IVOMD, % of OM)。正交对比用于分析草料质量随时间的变化，月份和牧场为固定效应（SAS 的 glimmix 程序）。牧草质量在 2019 年的生长季节呈二次下降（IVDMD，P = 0.02 和 IVOMD，P < 0.01）。2019 年 5 月，CWG 平均为 54.0% IVDMD 和 60.4% IVOMD，到 9 月 30 日降至 37.0% IVDMD 和 43.3% IVOMD。对于 2020 年收集的平均 43 个样本，未检测到月间 IVDMD (P = 0.57) 或 IVOMD (P = 0.53) 的显着差异。1% IVDMD 和 46.8% IVOMD。当降水不限制 CWG 时，草料质量在生长季节早期最高，随着成熟而降低。