Extension by Anowar Islam

Harvest and Storage Affect Forage Quality
By Anowar Islam, UW Extension Forage Specialist

    The forage quality, in general, of standing or live crops is always higher than hay and silage.
    Physical losses that impact the leaf component and respiration activity that uses nonstructural carbohydrates account for the quality reduction under harvest conditions. During harvest, if rain damage occurs, you can expect a larger reduction in quality, which is further enhanced by greater shattering, respiration and leaching of soluble constituents.
    Research shows that exposure to rain increases acid detergent fiber (ADF) and neutral detergent fiber (NDF) and decreases dry matter digestibility of both alfalfa and red clover. The quality of legume hays is reduced more than grasses by rain damage. It has been reported that 60 percent or more quality (e.g., dry matter, crude protein, digestible dry matter) loss on alfalfa may be caused by rain damage. The likelihood of rain damage, leaf loss and respiration can be reduced by harvesting forage as silage rather than hay.
    During the harvest, rain can take out readily soluble compounds such as sugars and potassium, and as a result rain-damaged hays might be deficient in these nutrients. Crude protein concentration may be lowered by rain damage in alfalfa hays, however, crude protein loss is slow and lower because of larger molecules of protein.
    During storage of hay or silage, forage quality can be reduced by many factors. These include weathering, microbial activity and some undesirable chemical reactions. It is normally expected that quality loss will be large if the hay is stored outside. Rainfall will enhance weathering and decrease forage quality of hays. Reports show that quality of weathered hays of mixed alfalfa-grass declines rapidly compared to hays stored indoors.
    Many factors (e.g., species, varieties, maturity stage, weather, etc.) can influence forage quality. Harvesting and storage system is one of the most important factors. Careful attention during harvesting, such as weather monitoring and appropriate storing, when possible, can reduce the forage quality loss and improve the value of harvested forages.
    Anowar Islam is an assistant professor and the UW Extension Forage Agroecologist in the Department of Plant Sciences in the College of Agriculture and Natural Resources. He can be reached at 307-766-4151 or mislam@uwyo.edu.