USDA-ARS (retired), US Dairy Forage Research Center, Marshfield, WI 54449, USA.
School of Plant Sciences, University of Arizona, Tucson, AZ 85721, USA.
J Anim Sci. 2022 Mar 1;100(3). doi: 10.1093/jas/skac020.
Recently, there has been interest in including triticale (X Triticosecale Wittmack) within forage programs in the southwest USA. Our objectives were to evaluate in vitro disappearance kinetics of neutral detergent fiber (NDF) and dry matter (DM) for cultivars identified during 2019 as positively or negatively deviant from typical cultivars, based specifically on regressions of 48-h in vitro disappearance of NDF on growth stage (GRST). All NDF analyses included the use of heat-stable α-amylase and sodium sulfite, as well as correction for residual ash (asNDFom). Seven triticale cultivars were established on December 18, 2019 at the University of Arizona Maricopa Agricultural Center, located near Maricopa, AZ. Forage plots were arranged in a randomized complete block design with three complete blocks (replications), and then harvested on seven dates the following late-winter and spring (February 26, March 17, April 1, April 14, April 28, May 12, and May 26). Based on a linear model, GRST was highly variable among cultivars on March 17 (44 ± 10.6), April 1 (57 ± 12.1), April 14 (67 ± 8.9), and April 28 (79 ± 7.2) compared with other harvest dates (SD ≤ 1.7). For concentrations of asNDFom, all cultivars exhibited linear (P ≤ 0.042) and quadratic (P < 0.001) polynomial contrasts in response to harvest date, and all cultivars except Merlin Max (P ≥ 0.063) exhibited at least one additional cubic or quartic effect (P ≤ 0.015). A contributing factor to the unique response by Merlin Max was the numerically greater maximum canopy height (145 ± 9.8 cm) compared with the mean of all cultivars (107 ± 17.7 cm), which also was associated with greater percentages of stem, as well as reduced percentages of DM partitioned within the grain head. Regressions of asNDFom disappearance after 30- or 48-h incubations on GRST indicated this was an effective independent variable (R2 ≥ 0.927), and responses were most often linear in nature. Generally, relationships for DM disappearance were quadratic, ostensibly due to the complicating effect of grain fill, but GRST was again an effective predictor variable with R2 statistics ≥ 0.852 for 12 of 14 combinations of cultivar and incubation time. Predicted percentages of digestible DM attributed to asNDFom disappearance were ≥50.3% through the fully flowered stage of growth, but digestible contributions from nonfiber components following the onset of grain fill profoundly affected overall DM digestibility among cultivars harvested at later GRST.
最近，人们对在美國西南部的饲料计划中包含黑小麦（X Triticosecale Wittmack）产生了兴趣。我们的目标是根据 48 小时体外中性洗涤纤维（NDF）消失率对生长阶段（GRST）的回归，评估在 2019 年被确定为与典型品种正偏离或负偏离的品种的体外 NDF 和干物质（DM）消失动力学。所有 NDF 分析均包括使用耐热α-淀粉酶和亚硫酸钠，以及对残余灰分（asNDFom）进行校正。2019 年 12 月 18 日，在亚利桑那州马里科帕农业中心的亚利桑那大学建立了 7 个黑小麦品种，该中心位于亚利桑那州马里科帕附近。饲草地块采用随机完全区组设计布置，有三个完整区组（重复），然后在接下来的隆冬和春季的七个日期进行收获（2 月 26 日、3 月 17 日、4 月 1 日、4 月 14 日、4 月 28 日、5 月 12 日和 5 月 26 日）。基于线性模型，与其他收获日期相比，3 月 17 日（44±10.6）、4 月 1 日（57±12.1）、4 月 14 日（67±8.9）和 4 月 28 日（79±7.2）的品种之间 GRST 差异很大（SD≤1.7）。对于 asNDFom 浓度，所有品种对收获日期均表现出线性（P≤0.042）和二次（P<0.001）多项式对比，除 Merlin Max 外，所有品种（P≥0.063）均表现出至少一种额外的三次或四次效应（P≤0.015）。 Merlin Max 独特反应的一个促成因素是与所有品种的平均值（107±17.7cm）相比，数值上更大的最大冠层高度（145±9.8cm），这也与更大比例的茎以及减少的 DM 分配在谷物头部有关。30 或 48 小时孵育后 asNDFom 消失的回归表明这是一个有效的独立变量（R2≥0.927），并且响应通常是线性的。一般来说，DM 消失的关系是二次的，显然是由于谷物填充的复杂影响，但 GRST 再次是一个有效的预测变量，对于 14 个品种和孵育时间的 12 种组合，R2 统计数据≥0.852。归因于 asNDFom 消失的可消化 DM 的预测百分比≥50.3%，直到生长的完全开花阶段，但谷物填充开始后非纤维成分的可消化贡献对收获时品种之间的整体 DM 消化率有深远影响。
