Wet growing conditions and short harvest windows during the 2019 season may have resulted in harvesting at higher moisture levels, which can increase the risk of a clostridial fermentation.
Anytime forage is harvested below 30% dry matter (DM), there is a risk of clostridial fermentation, especially in legumes and grasses. Clostridia are soil microorganisms naturally present on forages.
In corn silage, clostridial growth is rarely an issue – even if wet – but the extra moisture may stimulate microbial activity in general. When allowed to grow, clostridia can produce butyric acid and a range of biogenic amines, resulting in a telltale fecal, or putrid, smell that can cause feeding issues.
As anaerobic microbes, clostridia will grow even in well-packed silage if the pH is above 5.0. However, clostridia can also occur in aerobically unstable silages, as growth of the aerobic spoilage organisms creates anaerobic zones.
Spoiled silage with an elevated pH can allow other microbes to grow. Reducing spoilage can improve feed intake. Cattle don’t want to eat spoiled silage. It is less palatable, and even a small amount of spoiled silage can reduce dry matter intake.1
One key to creating stable silage is to ensure a rapid lactic acid fermentation. This gets the pH down below 5.0 quickly and helps prevent clostridial and enterobacterial fermentations. Harvesting at an adequate DM level, proper packing at ensiling, covering and sealing the structure quickly and efficiently, and using a research-proven forage inoculant for a fast initial ensiling fermentation all help reduce the chances of clostridia growth.
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1 Whitlock LA et al. Effect of level of surface-spoiled silage on the nutritive value of corn silage-based rations. Cattlemen’s Day 2000. Accessed May 21, 2015. Available at: http://krex.k-state.edu/dspace/bitstream/handle/2097/4652/cattle00pg22-24.pdf?sequence=1
