本试验在规模化牧场中目前采用的青贮装填、压实、封盖等管理条件下，分析不同深度全株玉米青贮常规营养价值、发酵品质以及奶牛瘤胃降解率的差异，为合理生产和取用全株玉米青贮提供理论支持和实践指导。试验采集黑龙江地区牧场中大型青贮窖全株青贮样品（n=6），以上层、中层、下层为切入点，测定不同深度全株玉米青贮常规营养价值、发酵品质、瘤胃内7 h淀粉降解率以及24、30和48 h干物质降解率（DMD）、中性洗涤纤维降解率（NDFD）和粗蛋白质降解率（CPD）。对于发酵品质，测定pH、淀粉、乳酸、乙酸、氨态氮含量及乳酸菌、酵母菌和霉菌数量这8个指标，通过模糊数学隶属函数值法进行综合评价。结果显示：1）青贮窖内不同深度的全株玉米青贮干物质、中性洗涤纤维、酸性洗涤纤维及淀粉含量均随青贮窖深度的增加而下降（P>0.05）；且粗蛋白质、粗灰分和酸性洗涤蛋白质含量各层间差异不显著（P>0.05）。2）青贮窖中层的全株玉米青贮的综合评价值最高，下层其次，上层最低。3）对于青贮窖不同深度全株玉米青贮的DMD，在24 h时，各层间差异均不显著（P>0.05），但达到30 h后，中层全株玉米青贮DMD显著高于上层（P<0.05），但与下层差异不显著（P>0.05）。在24和30 h时，各层间NDFD差异均不显著（P>0.05）；在48 h时，中层和下层全株玉米青贮NDFD均显著高于上层（P<0.05），但中层和下层间差异不显著（P>0.05）。而不同深度全株玉米青贮CPD和淀粉降解率，在3个时间点均无显著性差异（P>0.05）。结果表明，青贮窖内不同深度全株玉米青贮质量存在显著差异，随着青贮窖内深度的增加，干物质及淀粉等养分损失率增加，但pH、有机酸等发酵效果更好，并增加了瘤胃降解率。然而达到一定深度后，发酵品质趋于稳定，综合评价结果显示中层全株玉米青贮质量最佳。因而，在青贮制作过程中，应注重逐层压窖，推荐使用隔氧膜封窖。在取料过程中，上层、下层均匀取料，降低青贮饲料对饲粮配方一致性的影响。

The purpose of this experiment was to study the difference of conventional nutritional value, fermentation quality and rumen degradation rate of whole plant corn silage at different depths in silage silo under the most common silage filling, compaction, sealing and other management strategies for large-scale farms, and to provide theoretical support and practical guidance for rational production and utilization of whole plant corn silage. The silage samples were collected from large-scale farms (n=6) in Heilongjiang province. The conventional nutritional value, fermentation quality, starch degradation rate at 7 h, dry matter degradation rate (DMD), neutral detergent fiber degradation rate (NDFD) and crude protein degradation rate (CPD) at 24, 30 and 48 h of whole plant corn silage samples at different depths (upper, middle and under layers) were determined. For fermatation qualiy, the pH, contetns of starch, lactic acid, acetic acid, ammonia nitrogen and the amount of lactic acid bacteria, yeast and mold were determined, and then comprehensive evaluation was analyzed by membership function. The results showed as follows:1) the contents of dry mater, neutral detergent fiber and starch decreased with the increase of the depth of silage silo, but there was no significant difference in the contents of nutrients (P>0.05). Besides, there was no significant difference in contents of crude protein, crude ash and acid deter gent insoluble crude protein among three layers (P>0.05). 2) The results of comprehensive evaluation value of the whole corn silage in the middle layer was the highest, followed by the under layer, and the upper layer was the lowest. 3) For DMD of whole plant corn silage in different depths of silage silo, there was no significant difference among layers at 24 h (P>0.05), but after 30 h, DMD of whole plant corn silage in the middle layer was significantly higher than that in upper layer (P<0.05), but there was no significant difference between middle and under layers (P>0.05). For the NDFD, there was no significant difference among three layers at 24 and 30 h (P>0.05); however, after 48 h degradation in the rumen of cows, the NDFD in the middle and under layers was significantly higher than that in the upper layer (P<0.05), but the difference between the middle and under layers was not significant (P>0.05). At three time points, there was no significant difference in CPD and starch degradation rate of silage samples at different depths (P>0.05). It is concluded that there is significant differences in the quality of whole plant corn silage at different depths in the silage silo. With the increase of the depth of silage in silage silo, the loss rate of DM, starch and other nutrients increase, but the fermentation effects of pH and organic acids are better and rumen degradability increases. However, after reaching a certain depth, the fermentation quality tends to be stable, and the comprehensive evaluation results show that whole plant corn silage in the middle layer has the best quality. Therefore, in the process of silage production, we should pay attention to layer-by-layer compactionto, and the utilization of oxygen barrier membrane is recommend. In the feeding process, the material should be taken from top to bottom uniformly to reduce the impact of silage on consistency of diets.