155 Modulating silage fermentation with microbial inoculants

Silage is a vital feed ingredient for beef and dairy cattle diets in many areas worldwide. Even though ensiling is a well-established method of forage preservation, producers face a myriad of challenges to produce, harvest, and store forages optimally. Challenging circumstances like these create difficulties for proper silage fermentation, increase dry matter (DM) losses and silage contamination with mycotoxins, and reduce the nutritive value of ensiled forages. Losses of DM and nutrients occur during production, fermentation, and feeding of silage. Although some losses are unavoidable, poor management may increase DM losses up to 60% which may eventually lead to decreased feed efficiency, as each percentage-unit lost as DM is a percentage-unit of feed that cannot be converted into animal products. Loss of DM during forage production and preservation is estimated to cost beyond a billion dollars worldwide. Even in well-managed silages, yeasts and molds that survive anaerobic fermentation may grow rapidly and reduce aerobic stability after silo opening, and mold count in silage is positively related to DM loss. The use of silage microbial inoculants is a key strategy to modulate silage fermentation and preserve forage successfully. This presentation will discuss microbial inoculant strategies to optimize silage fermentation and minimize silage losses. Homofermentative bacterial inoculants, which contain bacteria that almost exclusively produce lactic acid, have been shown to effectively reduce silage pH and improve DM recovery. The use of homofermentative microbial inoculants have been shown to attenuate DM loss during ensiling and to increase dry matter intake and hence lactation performance by dairy cows. Heterofermentative bacterial inoculants, which contain bacteria capable of producing both lactic and acetic acids, reduce mold and yeast counts and improve silage aerobic stability.