Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 6/1/2001
Publication Date: 11/1/2003
Citation: Muck, R.E., Moser, L.E., Pitt, R.E. 2003. Post-harvest factors affecting ensiling. In: Buxton, D.R., Muck, R.E., Harrison, J.H., editors. Silage Science and Technology. Madison, WI: American Society of Agronomy, Crop Science Society of America, Soil Science of America. p. 251-304. Interpretive Summary:
Technical Abstract: The primary goal in the harvesting and ensiling of a crop is to preserve as nearly as possible the quantity and quality of the crop at the time of cutting. The mowing, wilting and chopping operations generally have relatively small direct effects on the ensilability of a crop except for rainfall during wilting. Rainfall can leach sugars, and rewetting can cause additional plant and microbial respiration. On the other hand, the timing of these operations determines the moisture content of the crop at ensiling. Moisture content affects either directly or indirectly all of the physical, biological and chemical processes in the silo. Crops ensiled too wet are subject to effluent losses and clostridial fermentation, reducing feeding value of the silage. Crops ensiled too dry are more porous and consequently more susceptible to aerobic microbial spoilage and Maillard product formation. The other major factor affecting silage quality is exposure of the crop to oxygen. Various areas of ensiling management determine this: chop length, the speed of filling, the degree to which the crop is packed in the silo, how well the silo is sealed, the feedout rate, and how silage is removed from the silo. Exposure to oxygen in the early stages of ensiling prolongs plant respiration, permits the growth of aerobic spoilage microorganisms which may predispose a silage to heating during feedout, and may cause sufficient heating to promote the formation of Maillard products. Oxygen later during storage promotes primarily aerobic microbial spoilage, which in turn can cause heating and the promotion of pathogenic microorganisms. Overall, good ensiling management aims to ensure a fast and efficient lactic acid bacterial fermentation and minimize plant and microbial respiration.