本试验旨在研究留茬高度对全株玉米青贮品质的影响，并探讨对于不同特性的玉米品种应如何选择留茬高度，为合理生产和利用全株玉米青贮提供理论支持。选取黑龙江省广泛种植玉米品种——高淀粉品种阳光1号、高蛋白质品种中原单32和高产量品种龙福208 3种不同特性的全株玉米为试验材料，采用单因素试验设计，设置19、49 cm 2个留茬高度，共6个处理，每个处理3个重复。测定常规营养成分含量、发酵品质及24、30和48 h瘤胃降解率。结果显示：1）对于全株玉米青贮营养成分含量，留茬高度由19 cm增加到49 cm后，3个品种的粗蛋白质（CP）、淀粉含量显著提高（P<0.05），中性洗涤纤维（NDF）及酸性洗涤纤维（ADF）含量显著降低（P<0.05），阳光1号、龙福208干物质（DM）和粗灰分含量显著提高（P<0.05）。2）各处理全株玉米青贮pH差异不显著（P>0.05）；随着留茬高度的增加，同一品种全株玉米青贮氨态氮/总氮（NH₃-N/TN）显著降低（P<0.05），但中原单32在49 cm留茬高度下的NH₃-N/TN仍显著高于阳光1号19 cm留茬高度下的NH₃-N/TN（P<0.05），具有较高的蛋白质分解量，而阳光1号NH₃-N/TN在2个留茬高度下均较低，发酵效果更好；乳酸（LA）及乙酸（AA）含量在不同品种间有较大差异，而增加留茬高度对其影响较小。3）随着留茬高度的增加，各品种全株玉米青贮的瘤胃干物质降解率（DMD）和粗蛋白质降解率（CPD）呈增加趋势，瘤胃中性洗涤纤维降解率（NDFD）呈降低趋势，其中阳光1号在49 cm留茬高度下48 h瘤胃DMD最大，与19 cm留茬高度处理差异不显著（P>0.05），且该品种在19 cm留茬高度下48 h瘤胃NDFD最大。由此可见，增加留茬高度可提高全株玉米青贮的DM、CP、淀粉含量，但会降低其NDF含量，以及减小发酵过程的缓冲性，从而对发酵指标影响较小。因此，对于高淀粉低纤维类玉米品种如阳光1号，可选择较低留茬高度，以获得质与量最大化；而高蛋白质或高产量玉米品种如中原单32、龙福208，可适当提高留茬高度，改善青贮品质。

The purpose of this experiment was to study the effects of cutting height on the quality of whole plant corn silage and explore the suitable cutting height for different corn varieties, which would provide a theoretical basis for producing and utilizing of whole plant corn silage. Three corn varieties widely cultivated in Heilongjiang province including high starch variety of Yangguang No.1, high protein variety of Zhongyuandan 32 and high biology yield variety of Longfu 208 were studied in this experiment. Using a single factor design, two cutting heights of 19 and 49 cm were set. There were 6 treatments with 3 replicates per treatment. Nutrient contents, fermentation quality and ruminal degradation rate at 24, 30 and 48 h were measured. The results showed as follows:1) about nutrient contents of whole plant corn silage, when the cutting height was increased from 19 cm to 49 cm, contents of crude protein (CP) and starch were significantly increased (P<0.05), while the contents of neutral detergent fiber (NDF) and acid detergent fiber (ADF) were significantly decreased in three corn varieties (P<0.05), and the contents of dry matter (DM) and ash of Yangguang No.1 and Longfu 208 were significantly increased (P<0.05). 2) There was no significant difference of pH among treatments (P>0.05). With the increase of cutting height, ammonia nitrogen/total nitrogen (NH₃-N/TN) of the same corn variety significantly decreased (P<0.05). NH₃-N/TN of Zhongyuandan 32 at cutting height of 49 cm was still significantly higher than that of Yangguang No.1 at cutting height of 19 cm (P<0.05), which indicated a higher protein decomposition in Zhongyuandan 32 at cutting height of 49 cm. At cutting heights of 19 and 49 cm, NH₃-N/TN of Yangguang No.1 was lower, which indicated a better fermentation quality of Yangguang No.1. For the contents of lactic acid and acetic acid, there were differences among different corn varieties, and cutting height had little effect on them. 3) With the increase of cutting height, ruminal dry matter degradation rate (DMD) and crude protein degradation rate (CPD) of all varieties of whole plant corn silage increased, while ruminal neutral detergent fiber degradation rate (NDFD) decreased. At cutting height of 49 cm, the 48 h ruminal DMD of Yangguang No.1 was the largest, had no significant difference with that at cutting height of 19 cm (P>0.05), and Yangguang No.1 had the largest 48 h ruminal NDFD at cutting height of 19 cm. The results indicate that increasing cutting height can improve DM, CP and starch contents of whole plant corn silage, but decrease NDF content, and decrease buffering capacity of fermentation process, thus has a little effect on fermentation indexes. Therefore, the cutting height of high starch variety of whole plant corn silage, such as Yangguang No.1, can be moderately dropped, so that the quality and yield can be raised; however, the cutting heights of high protein variety and high biology yield variety of whole plant corn silage, such as Zhongyuandan 32 and Longfu 208, can be increased properly to improve the quality of silage.