ABSTRACT
Summary Two experiments were carried out from 1976 to 1980 to ascertain the effect of delayed sealing of silo on fermentation, dry-matter (DM) loss, digestibility, and silage intake. The effect of delayed sealing (up to 72 hours) of grass and corn silage was tested in laboratory silos on fermentation quality with storage temperatures at 15°C and 30°C, moisture content from 49% to 85%, water-soluble carbohydrate (WSC) content ranging from 11.1% to 17.5%, and with and without an addition of 0.25% formic acid. In all cases, delayed sealing resulted in poor-quality silage with high pH values and low lactic acid content. Moreover, deterioration of silage quality was accelerated by increases in delay time, storage temperature, moisture content, and lowering of WSC content of the ensiled materials. Addition of formic acid before ensiling eliminated deterioration of silage quality caused by the delayed sealing. High-moisture Italian ryegrass was harvested with a cylinder harvester at early heading stage and ensiled three times in each of two 4.5-m3 experimental tower silos. The green forage contained 14.1% DM, 15.1 ± 1.2% WSC, and 13.6 ± 0.8% crude protein on a DM basis. Silo 1 was sealed immediately after each ensiling by using the plastic-bag-liner method; silo 2 was sealed after 48 hours' delay at each ensiling (open for a total of 144 hours) using the same plastic-bag-liner method. During ensiling in the silo where sealing had been delayed, maximum fermentation temperature in the middle layer was 34.9° ± 1.6°C and 50.8°C in the top layer. By comparison, in the silo that had been sealed immediately, maximum temperature was 22.0° ± 0.8°C. Delayed sealing produced silages of high pH values with high butyric acid and volatile-base nitrogen (VBN) and low lactic acid content. DM losses during ensiling were also high in these aerated silages. The DM digestibility (in vivo) and intake of silage from the silo that had been sealed immediately was slightly higher, although not statistically significantly so, than the aerated silage. From these experiments, it is concluded that delayed sealing of a silo not only has an immediate effect on the upper layers of the ensiled mass but also can cause deterioration of the lower layers even after sealing has been accomplished. Moreover, the effect of delayed sealing on fermentation and DM loss may be increased by attendant conditions of warm weather and low DM and WSC contents of the ensiled materials.
