Q. We prepared inoculant but experienced a delay in ensiling. How long does the inoculant remain viable after mixing?
A. Nothing is more important for successful inoculation than the viability of the microbes.
Most commercial inoculants are freeze-dried fermentation products added to a carrier, usually a sugar-based mixture..
The temperature of the rehydrated, mixed product is critical to viability and "shelf-life." . Research shows a temperature of 84ºF can begin to reduce inoculant viability. At 95ºF inside the applicator tank under field conditions, the inoculant viability was reduced by 50 percent. At 110ºF, viability was just 10 percent. In the study, bacteria viability was poorer for dark-colored tanks due to generally higher temperature in these systems. You can buy more time after mixing by using insulated tanks, typically found on low-volume applicators, to help keep temperatures low.1
Response to temperature in this study did vary with the product and the microbial strains used.. For example, Lactobacillus plantarum and L. buchneri 40788 were better able to withstand the temperatures studied. 1 At the highest temperature (113°F) even these hardiest strains suffered a ten-fold decrease over four hours, hence the importance of keeping products cool!
Water used to rehydrate and dilute liquid inoculants should not contain high levels of chlorine, which can kill the bacteria. Inoculants containing a stability enhancer can help bacteria withstand more variable conditions and can extend the life of the product. For example, Biotal® forage inoculants contain an advanced rehydration stability enhancer. If kept cool (less than 77°F), the product will remain viable for three to five days and can withstand chlorine within potable (drinking water) levels (i.e. up to one ppm). Keeping mixed product out of the sun will help it remain viable longer. Fresh mixed product made with clean, potable water can be kept in a refrigerator for up to six days.
Be aware of the storage conditions and temperature before, during and after mixing your inoculant. Maintaining the viability of these important bacteria helps ensure for the value of your inoculant investment and successful ensiling as part of a good management program. In the long run, it will lead to high-quality feedstuffs with good feedout stability for your operation.
I hope this information helps.
The Silage Dr.
1 Mulrooney CN et al. Short Communication: The Effect of Water Temperature on the Viability of Silage Inoculants. Journal of Dairy Science;(91) Issue 1: 236-240.
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