Zhang Fuquan, Brattain Rebecca S, Wehrle Herman, Baron Vern S, Ribeiro Gabriel O, Penner Gregory B
Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, Canada S7N 5A8.
KWS Cereals USA, LLC, Champaign, IL, USA 61822.
J Anim Sci. 2025 Jan 4;103. doi: 10.1093/jas/skaf230.
The objective of this study was to evaluate the effects of feeding hybrid rye silage (HRS) as a replacement for barley silage (BARS) on dry matter intake (DMI), ruminal fermentation, and the site and extent of digestion when fed to growing beef heifers. Eight ruminally cannulated Hereford × Simmental heifers (519 ± 25.8 kg BW) were used in a replicated 4 × 4 Latin square design with 28-d periods, including 21 d for dietary adaptation and 7 d for data and sample collection. Treatments included a control diet (BCON) that contained 59.62% BARS (harvested at the soft dough stage of maturity), 38.61% barley grain, and 1.78% of a vitamin and mineral supplement on a dry matter (DM) basis. The HRS (harvested at the boot stage of maturity) replaced 33% (RLOW), 67% (RMED), or 100% (RHIGH) of the BARS on a DM basis. Increasing HRS inclusion linearly (P = 0.04) decreased DMI, linearly increased water intake (P = 0.02) and mean ruminal pH (P < 0.01) and linearly decreased the duration that ruminal pH was < 5.8 (P = 0.04). There was no effect of HRS inclusion on total short-chain fatty acid (SCFA) concentration (P = 0.46) in ruminal fluid, but the molar proportion of acetate linearly (P < 0.01) increased while propionate and butyrate linearly decreased (P < 0.01). The NH3-N concentration linearly increased (P = 0.03) with increasing HRS inclusion. Increasing HRS inclusion increased ruminal degradability of DM, OM, and aNDFom, while there was no effect on intestinal digestibility of nutrients, either expressed as a percent of intake or percent of digesta flow. Total tract digestibility of DM (P ≤ 0.01), ADF (P ≤ 0.01), and aNDFom (P ≤ 0.01) increased with increasing HRS inclusion, but inclusion did not affect gross energy (GE) digestibility (P = 0.15) and the dietary digestible energy (DE) concentration (P = 0.17). In conclusion, the use of HRS, harvested at the boot stage, as a direct replacement for BARS, harvested at the soft dough stage, is likely to reduce DMI but improve NDF digestibility without affecting dietary DE concentration. As there was no difference in GE digestibility or dietary DE digestibility, these results demonstrate a tradeoff between greater NDF digestibility of HRS compared to BARS but reduced DMI with increasing inclusion.
本研究的目的是评估用杂交黑麦青贮饲料（HRS）替代大麦青贮饲料（BARS）对生长育肥牛干物质采食量（DMI）、瘤胃发酵以及消化部位和消化程度的影响。选用8头装有瘤胃瘘管的赫里福德×西门塔尔小母牛（体重519±25.8千克），采用重复4×4拉丁方设计，每期28天，其中包括21天的日粮适应期和7天的数据及样本采集期。处理组包括一种对照日粮（BCON），以干物质（DM）计，其含有59.62%的BARS（在成熟软面团期收获）、38.61%的大麦籽粒以及1.78%的维生素和矿物质预混料。以DM计，HRS（在孕穗期收获）替代了33%（RLOW）、67%（RMED）或100%（RHIGH）的BARS。随着HRS添加量的线性增加（P = 0.04），DMI降低，饮水量（P = 0.02）和瘤胃平均pH值（P < 0.01）线性增加，瘤胃pH值<5.8的持续时间线性降低（P = 0.04）。HRS添加量对瘤胃液中总短链脂肪酸（SCFA）浓度无影响（P = 0.46），但乙酸的摩尔比例线性增加（P < 0.01），而丙酸和丁酸线性降低（P < 0.01）。随着HRS添加量的增加，NH3 - N浓度线性增加（P = 0.03）。增加HRS添加量可提高DM、OM和aNDFom的瘤胃降解率，但对营养物质的肠道消化率无影响，无论是以摄入量的百分比还是消化物流量的百分比表示。随着HRS添加量的增加，DM（P≤0.01）、ADF（P≤0.01）和aNDFom（P≤0.01）的全肠道消化率增加，但添加量对总能（GE）消化率（P = 0.15）和日粮可消化能量（DE）浓度无影响（P = 0.17）。总之，在孕穗期收获的HRS直接替代在软面团期收获的BARS，可能会降低DMI，但提高NDF消化率且不影响日粮DE浓度。由于GE消化率或日粮DE消化率无差异，这些结果表明，与BARS相比，HRS的NDF消化率更高，但随着添加量增加DMI降低，二者之间存在权衡。
