ABSTRACT

The occurrence of the Western corn rootworm and increasing frequency of summer droughts have reduced forage maize yields and quality in Central Europe in recent years. Therefore, sorghum (Sorghum bicolor (L.) Moench) has been increasingly used as alternative forage in ruminant feeding, although information on the nutritive value of whole crop sorghum silage (WCSS) under Central European climate conditions is scarce. This research project aimed to study differences between sorghum varieties and harvest dates regarding dry matter (DM) yield, chemical composition of fresh panicle, fresh stover, fresh whole plant and WCSS as well as whole tract digestibility and energy content of WCSS. For this purpose, six sorghum varieties, classified by their predominant use (biomass, silage, grain), were cultivated and harvested at three maturity stages (late milk stage, dough stage, full maturity). Furthermore, WCSS quality was compared with feed value of fresh and ensiled forage maize. Dry matter yield was higher (p < 0.05) in biomass sorghum (24.9 t/ha) compared to other sorghum varieties (12.4 to 16.7 t/ha). However, panicle proportion was lowest in biomass sorghum (10.5%), highest in grain sorghum (59.1%) and intermediate in silage sorghum. Fibre content declined and starch content increased with rising panicle proportion in fresh panicle, fresh whole plant and WCSS. Therefore, whole tract organic matter digestibility (66.8%) and metabolisable energy (ME) content (9.49 MJ/kg DM) were highest in grain sorghum silage. Especially low ME content was found in the biomass sorghum silage (7.43 MJ/kg DM). Dry matter yield of sorghum increased between late milk and dough stage of maturity, while it remained constant afterwards. Furthermore, ME content of WCSS rose tendentially (0.05 < p < 0.10) between late milk and dough stage of maturity and dropped again between dough stage and full maturity. Highest nutritive value of WCSS is achieved if grain sorghum varieties are used and both nutritive value and DM yield are optimised if harvest is carried out at dough stage of maturity. However, compared to forage maize, grain sorghum varieties have disadvantages both in DM yield and in nutritive value under common Central European climate conditions.

摘要

近年来，西部玉米根虫的发生和夏季干旱频率的增加降低了中欧的饲料玉米产量和质量。因此，高粱（Sorghum bicolor(L.) Moench) 已越来越多地用作反刍动物饲养的替代饲料，尽管关于中欧气候条件下全作物高粱青贮饲料 (WCSS) 营养价值的信息很少。本研究项目旨在研究高粱品种和收获日期在干物质 (DM) 产量、新鲜穗、新鲜秸秆、新鲜整株和 WCSS 的化学成分以及 WCSS 的全道消化率和能量含量方面的差异。为此，按照主要用途（生物质、青贮饲料、谷物）分类的六个高粱品种在三个成熟阶段（牛奶后期、面团阶段、完全成熟）进行了栽培和收获。此外，WCSS 质量与新鲜和青贮饲料玉米的饲料价值进行了比较。干物质产量更高（p< 0.05) 与其他高粱品种（12.4 至 16.7 吨/公顷）相比，生物质高粱（24.9 吨/公顷）。然而，穗比例在生物质高粱中最低（10.5%），在谷物高粱中最高（59.1%），在青贮高粱中居中。在鲜穗、鲜全株和WCSS中，随着穗比例的增加，纤维含量下降，淀粉含量增加。因此，谷物高粱青贮饲料的全道有机质消化率 (66.8%) 和代谢能 (ME) 含量 (9.49 MJ/kg DM) 最高。在生物质高粱青贮饲料中发现 ME 含量特别低（7.43 MJ/kg DM）。高粱的干物质产量在牛奶后期和面团成熟阶段之间增加，而之后保持不变。此外，WCSS 的 ME 含量呈上升趋势（0.05 <  p< 0.10) 在牛奶后期和面团成熟阶段之间，并在面团阶段和完全成熟之间再次下降。如果使用高粱品种，WCSS 的营养价值最高，如果在面团成熟阶段收获，营养价值和干物质产量都得到优化。然而，与饲用玉米相比，谷物高粱品种在中欧常见气候条件下在干物质产量和营养价值方面均存在劣势。