Grass Silage: A Critical Review of the Literature

This is the authors' abstract. We don't add key points for this paper.

The problems of preserving roughages for the winter feeding of livestock are perennial.The preservation of legumes and grasses as hay of high quality is governed mainly by two factors, namely, ideal curing weather, and stage of maturity of the crops.The inability of the livestock man to control these factors results in heavy nutrient losses in the hays during the curing process due to leaching and the loss (shattering) of leaves.The development of an alternate process of preservation has been the objective of investigators for years.Artificial dehydration of the hay crops shows some promise but, as yet, the process involves a large capital outlay and high operating costs.This at present eliminates it from consideration by the average livestock man.Preserving these crops as silage seems to be the most logical approach to the solution of this problem.If they can be preserved as silage and stored irrespective of weather, the common haymaking losses will be reduced to a marked extent.However, early attempts to ensile crops of high protein content such as legumes usually met with failure.In many instances an unpalatable silage resulted with a putrid odor and an excessive loss of nutrients.These undesirable factors were attributed by Aldershaw (2) and Whittet (109) to a low content of fermentable carbohydrates in the ensiled material coupled with the stage of growth and the moisture content of the plant material.In trying to improve the quality of the ensiled material, six methods of preservation have been investigated.The principles involved were :1.The addition of various acids to the green material as it was being ensiled which thereby increased the acidity of the mass to a point where undesirable bacterial action was checked (22).2. The addition of fermentable carbohydrates to the fodder which favored the desirable lactic acid fermentation and resulted in a natural increase in acidity (82, 110).3. The inoculation of the fodder with a culture of lactic acid-forming bacteria to increase the number of desirable bacteria which caused a more rapid fermentation and thereby checked the activity of the undesirable organisms (47).4. The partial wilting of the grasses before ensiling to reduce the bacterial activity (113).