Corn silage is popular as a forage source for dairy cows due to its high energy and digestibility. It should have a light, pleasant smell with only a slight vinegar odor. Knowledge of the silage process often explains why some silage may be of poor quality. Once ensiled, the material starts to ferment and will continue to do so until enough acid is produced to stop bacterial action. The desired degree of acidity, a pH of about 4.2, should occur within 3 weeks after the silo is filled. Three different kinds of silage may be recognized according to the temperature during fermentation: 1) underheated silage is drab green in color and has a strong odor, slimy soft tissues and a pH of 5 or above; 2) overheated silage ranges from brown to black and usually has a caramel odor of slightly burned sugar; 3) properly heated silage is light green to yellow in color and has a vinegar type odor, firm plant tissues and a pH below 4.5.

Usually, a lot of attention is given to the grain portion of the corn being harvested for corn silage, but what about the leaves and stalk portions? Corn leaves are much more digestible than the stalk portion of the plant; thus, any additional leaves have the potential to increase the total digestible nutrients of the plant. The extra leaf area placed above the ear stays green and leads to a longer filling period for the kernels. Micro-organisms (bacteria) present on the aerial part of the plants are important for the fermentation process occurring in the silo. Researchers found that the total numbers of micro-organisms was higher on the leaves than on the stems in all phases of development of corn. Furthermore, the number of lactic acid bacteria increased with the growth of the plants. Fungi and yeasts can be detrimental for leaf health and can interfere with corn silage quality. Read more 

Follow the read more link above to read the full article authored by Dr. Phil Cardoso, University of Illinois, Dairy Professor.