How do relocation time and length of storage after relocation affect fermentation and nutritive value of corn silage?

ABSTRACT This study aimed to determine the effects of relocation time (RT; Experiment 1) and storage time after relocation (ST; Experiment 2) on microbial population, fermentative characteristics, and chemical composition of corn silage. In experiment 1, corn silage was stored for 30 d, subjected to different RT (0–60 h), and stored again for 30 d. Thirty experimental silos were used in a completely randomized design, with three replicates per treatment. In experiment 2, after 150 d of ensiling, silage was removed from a bunker silo, exposed to air for 9 h, relocated to experimental silos, and stored for periods ranging from 0 to 128 d. Twenty-eight experimental silos were used in a completely randomized design, with four replicates per treatment. Relocation time had no effect on fungi counts and concentrations of lactic and propionic acids in corn silage but resulted in a significant increase in dry matter content. In experiment 2, dry matter recovery and concentration of non-fiber carbohydrates decreased in corn silage stored for more than 32 d after relocation. Exposure of corn silage to air during relocation for up to 60 h followed by 30 d of storage did not compromise the fermentation profile or nutritive value of the silage. Increased storage time of relocated corn silage (up to 128 d) consistently decreases its nutritional value. The storage period seems to have an increased impact on nutrient loss in relocated silage than the relocation period.

摘要 本研究旨在探究移仓时间（relocation time, RT；试验1）与移仓后储存时间（storage time after relocation, ST；试验2）对玉米青贮料（corn silage）的微生物种群、发酵特性及化学成分的影响。试验1中，玉米青贮料先经30 d青贮发酵储存，随后接受0~60 h的不同时长移仓处理，之后再次储存30 d。本试验采用完全随机设计（completely randomized design），共设置30个试验青贮窖，每个处理设置3次重复。试验2中，玉米青贮料经150 d青贮发酵后，从壕沟式青贮窖（bunker silo）中取出，暴露于空气9 h，随后转移至试验青贮窖中，储存时长为0~128 d。本试验采用完全随机设计，共设置28个试验青贮窖，每个处理设置4次重复。移仓时间对玉米青贮料的真菌菌落数（fungi counts）、乳酸（lactic acid）及丙酸（propionic acid）浓度无显著影响，但可显著提升其干物质（dry matter）含量。试验2中，移仓后储存时长超过32 d的玉米青贮料，其干物质回收率（dry matter recovery）与非纤维碳水化合物（non-fiber carbohydrates）浓度均出现下降。当玉米青贮料在移仓过程中暴露于空气的时长不超过60 h，且后续储存时长为30 d时，其发酵特征谱（fermentation profile）与营养价值（nutritive value）未受损害。随着移仓后玉米青贮料储存时长增加（最长至128 d），其营养价值持续下降。相较于移仓时长，储存期对移仓后青贮料的养分损失影响更为显著。