Department of Animal Science, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, SP, Brazil.
State University of Maringá, Maringá, PR, Brazil.
J Anim Sci. 2020 Feb 1;98(2). doi: 10.1093/jas/skaa007.
Exogenous fibrolytic enzymes (EFE) improve the energy availability of grains for nonruminant animals by reducing encapsulation of the endosperm nutrients within grain cell walls; however, these benefits are unknown in the treatment of corn-based silage for cattle. The objective of the present study was to evaluate the effects of adding EFE at ensiling on the nutritive value of high-moisture corn (HMC) and snaplage (SNAP) for finishing Nellore bulls. The EFE dose was 100 g/Mg fresh matter in both HMC and SNAP. Diets were 1) a SNAP + HMC control (without enzyme addition); 2) SNAP + HMC EFE (with enzymes); 3) a whole-plant corn silage (WPCS) + HMC control (without enzyme addition); and 4) WPCS + HMC EFE (with enzymes). In addition to the silages, the diets were also composed of soybean hulls, soybean meal, and mineral-vitamin supplement. The statistical design was a randomized complete block with a factorial arrangement of treatments, and the experiment lasted 122 d. For in situ and in vitro analyses, 2 cannulated dry cows were used. There was no interaction between the diets and EFE application (ADG, P = 0.92; DMI, P = 0.77; G:F, P = 0.70), and there was no difference between the SNAP and WPCS diets regarding the DMI (P = 0.53), ADG (P = 0.35), and feed efficiency (ADG:DMI, P = 0.83). Adding EFE to the HMC and SNAP at ensiling did not affect ADG but decreased DMI (P = 0.01), resulting in greater feed efficiency by 5.91% (P = 0.04) than that observed in animals fed diets without the addition of EFE. Addition of EFE to HMC resulted in reduced NDF content and increased in vitro and in situ DM digestibility compared with untreated HMC. No effects were found for the addition of EFE to SNAP. Fecal starch decreased with EFE application (P = 0.05). Therefore, the diet energy content (TDN, NEm, and NEg) calculated from animal performance increased (P = 0.01) with the addition of EFE to HMC. In conclusion, exchanging the NDF from WPCS with that from SNAP did not affect the performance of finishing cattle, whereas the addition of EFE to HMC at ensiling improved animal performance by increasing the energy availability of the grain.
外源纤维酶（EFE）通过降低谷物胚乳营养物质在细胞壁内的包裹程度，提高非反刍动物对谷物的能量利用率；然而，其在牛用玉米青贮中的应用效果尚不清楚。本研究旨在评估青贮时添加 EFE 对育肥牛用高水分玉米（HMC）和青贮玉米（SNAP）营养价值的影响。EFE 添加量为 HMC 和 SNAP 每毫克新鲜物质 100 克。日粮分为 1）SNAP+HMC 对照组（未添加酶）；2）SNAP+HMC EFE 组（添加酶）；3）全株玉米青贮（WPCS）+HMC 对照组（未添加酶）；4）WPCS+HMC EFE 组（添加酶）。除青贮料外，日粮还包括大豆皮、豆粕和矿物质-维生素补充剂。试验采用随机完全区组设计，处理因素为析因设计，试验持续 122 天。进行原位和体外分析时，使用了 2 头带有套管的干奶牛。日粮和 EFE 应用之间没有相互作用（ADG，P=0.92；DMI，P=0.77；G:F，P=0.70），并且 SNAP 和 WPCS 日粮之间的 DMI（P=0.53）、ADG（P=0.35）和饲料效率（ADG:DMI，P=0.83）没有差异。青贮时在 HMC 和 SNAP 中添加 EFE 并不影响 ADG，但降低了 DMI（P=0.01），使饲料效率提高了 5.91%（P=0.04），高于未添加 EFE 的动物。与未处理的 HMC 相比，添加 EFE 可降低 HMC 的 NDF 含量，并提高体外和原位 DM 消化率。在 SNAP 中添加 EFE 没有效果。添加 EFE 后粪便淀粉减少（P=0.05）。因此，添加 EFE 可提高 HMC 日粮的动物性能计算的日粮能量含量（TDN、NEm 和 NEg）（P=0.01）。总之，用 SNAP 代替 WPCS 的 NDF 并不影响育肥牛的性能，而在青贮时添加 EFE 可通过提高谷物的能量利用率来改善动物性能。
