Impacts of some factors that effect spoilage of silage at the periphery of the exposed face of corn silage piles

Preserving silage in large piles is popular due to its flexibility and affordability that allows storage of large amounts of silage with low facility investment. Management of silage piles during feed-out impacts silage spoilage since, once the plastic covers are removed and silage near the exposed silage ‘face’ is exposed to air, undesirable microbes can proliferate to negatively impact its hygienic quality and nutritional value. Pile silage also has characteristics, such as a long feed-out phase and a large exposed face peripheral area, which makes it prone to spoilage during feed-out, especially in the exposed face area. Silage samples were collected from nine corn silage piles in the San Joaquin Valley of California (USA) in order to evaluate impacts of feed-out speed, days after opening and surface silage density on degree of silage spoilage at the periphery of the exposed face. Faster feed-out speed (i.e., 0.59 versus 0.29 m/day) suppressed the degree of spoilage, as indicated by lower temperature and pH, and higher lactic levels, as well as higher abundance of lactic acid bacteria (LAB). However, because surface spoilage in both fast- and slow-speed piles was judged to be in the spoilage initiation stage, the feed-out speed of 0.29 m/day was judged sufficient to prevent substantive spoilage. Fewer days after opening (i.e., 69 versus 110 days) impacted degree of spoilage as indicated by lower mold counts and higher lactic and acetic acid levels. As spoilage in long-open piles had reached mid-stage, while spoilage in short-open piles was still in the initiation stage, days after opening of 110 was judged too long to prevent surface spoilage. Higher surface density (i.e., 360 versus 312 kg/m³ wet weight) had little impact on spoilage, due to its low impact on all response parameters. Overall, faster feed-out speed and fewer days after pile opening had the most positive impacts on suppressing spoilage in corn silage at the periphery of the exposed face, while increasing surface silage density was less impactful.