Flores R, Coblentz W K, Ogden R K, Coffey K P, Looper M L, West C P, Rosenkrans C F
Department of Animal Science, University of Arkansas, Fayetteville 72701, USA.
J Dairy Sci. 2007 Jun;90(6):2883-96. doi: 10.3168/jds.2006-726.
Two tall fescue (Festuca arundinacea Schreb.) forages, one an experimental host plant/endophyte association containing a novel endophyte (HM4) that produces low or nil concentrations of ergot alkaloids, and the other a typical association of Kentucky 31 tall fescue and the wild-type endophyte (Neotyphodium coenophialum; E+), were autumn-stockpiled following late-summer clipping and fertilization with 56 kg/ha of N to assess the nutritive value and ruminal disappearance kinetics of autumn-stockpiled tall fescue forages. Beginning on December 4, 2003, sixteen 361 +/- 56.4-kg replacement dairy heifers were stratified by weight and breeding and assigned to one of four 1.6-ha pastures (2 each of E+ and HM4) that were strip-grazed throughout the winter. Pastures were sampled before grazing was initiated (December 4), each time heifers were allowed access to a fresh strip (December 26, January 15, and February 4), and when the study was terminated (February 26). For fiber components, there were no interactions between fescue type and sampling date for either pregrazed or postgrazed forages. Over sampling dates, neutral detergent fiber (NDF; 56.5 to 67.8%), acid detergent fiber (27.7 to 34.9%), hemicellulose (28.8 to 34.0%), cellulose (25.0 to 28.1%), and lignin (3.61 to 10.05%) varied with sampling date, but patterns were almost exclusively curvilinear with time. Ruminal disappearance rate of dry matter (DM) was not affected by any treatment factor (overall mean for both pregrazed and postgrazed forages = 0.050 h(- 1)); similar responses were observed for NDF disappearance (overall mean = 0.048 h(- 1)). Interactions of fescue type and sampling date were observed for both pregrazed and postgrazed forages with respect to effective ruminal disappearance of DM; however, estimates were relatively high for all forages (overall mean = 64.0%). Effective disappearance of NDF was relatively extensive for all forages (overall mean = 55.4% of NDF). Based on the results of this trial, the endophyte status of stockpiled tall fescue forages had little practical effect on forage nutritive value and kinetics of ruminal DM or NDF disappearance. Overall, autumn-stockpiled tall fescue forages would appear to be a legitimate and lower cost alternative to harvested forages, and appear to possess suitable nutritional characteristics for developing dairy heifers in the Ozark Highlands.
两种高羊茅（Festuca arundinacea Schreb.）草料，一种是实验性宿主植物/内生真菌组合，含有一种新型内生真菌（HM4），产生的麦角生物碱浓度低或为零，另一种是肯塔基31高羊茅与野生型内生真菌（Neotyphodium coenophialum；E+）的典型组合，在夏末修剪并施入56千克/公顷的氮肥后于秋季进行堆贮，以评估秋季堆贮高羊茅草料的营养价值和瘤胃消失动力学。从2003年12月4日开始，将16头体重361±56.4千克的后备奶牛按体重和繁殖情况分层，并分配到四个1.6公顷的牧场之一（E+和HM4各两个），整个冬季进行条带放牧。在放牧开始前（12月4日）、每次小母牛可以进入新的条带时（12月26日、1月15日和2月4日）以及研究结束时（2月26日）对牧场进行采样。对于纤维成分，预放牧和放牧后草料的羊茅类型与采样日期之间均无相互作用。在各个采样日期，中性洗涤纤维（NDF；56.5%至67.8%）、酸性洗涤纤维（27.7%至34.9%）、半纤维素（28.8%至34.0%）、纤维素（25.0%至28.1%）和木质素（3.61%至10.05%）随采样日期而变化，但模式几乎完全是随时间呈曲线变化。干物质（DM）的瘤胃消失率不受任何处理因素的影响（预放牧和放牧后草料的总体平均值=0.050小时-1）；NDF消失情况也观察到类似的反应（总体平均值=0.048小时-1）。对于预放牧和放牧后草料，在DM的有效瘤胃消失方面观察到羊茅类型与采样日期之间的相互作用；然而，所有草料的估计值都相对较高（总体平均值=64.0%）。所有草料的NDF有效消失相对广泛（总体平均值=NDF的55.4%）。根据该试验结果，堆贮高羊茅草料的内生真菌状况对草料营养价值以及瘤胃DM或NDF消失动力学几乎没有实际影响。总体而言，秋季堆贮的高羊茅草料似乎是收获草料的一种合理且成本较低的替代品，并且似乎具有适合在奥扎克高地培育后备奶牛的营养特性。
