Coblentz W K, Brink G E, Hoffman P C, Esser N M, Bertram M G
US Department of Agriculture-Agricultural Research Service (USDA-ARS), US Dairy Forage Research Center, Marshfield, WI 54449.
USDA-ARS, US Dairy Forage Research Center, Madison WI 53706.
J Dairy Sci. 2014 Mar;97(3):1645-60. doi: 10.3168/jds.2013-7232. Epub 2014 Jan 17.
Our objective was to assess the pasture productivity and forage characteristics of 2 fall-grown oat (Avena sativa L.) cultivars, specifically for extending the grazing season and reducing reliance on harvested forages by replacement dairy heifers. A total of 160 gravid Holstein heifers (80 heifers/yr) were stratified by weight, and assigned to 1 of 10 identical research pens (8 heifers/pen). Initial body weights were 480 ± 43.5 kg in 2011 and 509 ± 39.4 kg in 2012. During both years of the trial, four 1.0-ha pasture replicates were seeded in August with Ogle oat (Schumitsch Seed Inc., Antigo, WI), and 4 separate, but similarly configured, pasture replicates were seeded with Forage Plus oat (Kratz Farms, Slinger, WI). Heifer groups were maintained as units, assigned to specific pastures, and then allowed to graze fall-oat pastures for 6h daily before returning to the barn, where they were offered a forage-based basal total mixed ration. Two heifer groups were retained in confinement (without grazing) as controls and offered the identical total mixed ration as pasture groups. During 2011, available forage mass increased with strong linear and quadratic effects for both cultivars, peaking at almost 9 Mg/ha on October 31. In contrast, forage mass was not affected by evaluation date in 2012, remaining ≤ 2,639 kg/ha across all dates because of droughty climatic conditions. During 2012, Ogle exhibited greater forage mass than Forage Plus across all sampling dates (2,678 vs. 1,856 kg/ha), largely because of its more rapid maturation rate and greater canopy height. Estimates of energy density for oat forage ranged from 59.6 to 69.1% during 2011, and ranged narrowly from 68.4 to 70.4% during 2012. For 2011, responses for both cultivars had strong quadratic character, in which the most energy-dense forages occurred in mid November, largely due to accumulation of water-soluble carbohydrates that reached maximum concentrations of 18.2 and 15.1% for Forage Plus and Ogle, respectively. Across the 2-yr trial, average daily gain for grazing heifer groups tended to be greater than heifers remaining in confinement (0.85 vs. 0.74 kg/d), but both management strategies produced weight gains within reasonable proximity to normal targets for heifers in this weight range. Fall-grown oat should be managed as stockpiled forage for deferred grazing, and good utilization of fall-oat forage can be accomplished by a one-time removal of standing forage, facilitated by a single lead wire advanced daily to prevent waste.
我们的目标是评估两个秋季种植的燕麦（ Avena sativa L.）品种的牧场生产力和饲草特性，特别是为了延长放牧季节，并减少替代奶牛小母牛对收获饲草的依赖。总共160头怀孕的荷斯坦小母牛（每年80头）按体重分层，分配到10个相同的研究围栏中的1个（每个围栏8头小母牛）。2011年初始体重为480±43.5千克，2012年为509±39.4千克。在试验的两年中，8月在四个1.0公顷的牧场重复地块上播种了奥格尔燕麦（Schumitsch Seed Inc.，安蒂戈，威斯康星州），另外四个单独但配置相似的牧场重复地块播种了福瑞加燕麦（Kratz Farms，斯林格，威斯康星州）。小母牛组作为一个整体进行管理，分配到特定的牧场，然后每天在秋季燕麦牧场上放牧6小时，之后返回牛舍，在牛舍中为它们提供以饲草为基础的基础全混合日粮。将两个小母牛组圈养（不放牧）作为对照，并为其提供与牧场组相同的全混合日粮。2011年，两个品种的可用饲草量均呈显著的线性和二次效应增加，10月31日达到近9吨/公顷的峰值。相比之下，2012年的饲草量不受评估日期的影响，由于气候干旱，所有日期的饲草量均≤2639千克/公顷。2012年，在所有采样日期，奥格尔燕麦的饲草量均高于福瑞加燕麦（2678对1856千克/公顷），这主要是因为其成熟速度更快，冠层高度更高。2011年燕麦饲草的能量密度估计值在59.6%至69.1%之间，2012年则在68.4%至70.4%之间窄幅波动。2011年，两个品种的响应均具有强烈的二次特征，其中能量密度最高的饲草出现在11月中旬，这主要是由于水溶性碳水化合物的积累，福瑞加燕麦和奥格尔燕麦的水溶性碳水化合物最高浓度分别达到18.2%和15.1%。在为期两年的试验中，放牧小母牛组的平均日增重往往高于圈养的小母牛（0.85对0.74千克/天），但两种管理策略的增重都在该体重范围内小母牛正常目标的合理接近范围内。秋季种植的燕麦应作为储备饲草进行管理，用于延迟放牧，通过每天推进一根铅丝以防止浪费，一次性移除现存饲草，可以很好地利用秋季燕麦饲草。
