Practical research shared at International Silage Conference

By Dr. Michelle Windle, Vita Plus forage products and dairy technical services specialist
Every three years, the world’s foremost silage scientists gather to discuss the newest discoveries at the International Silage Conference.  This year, 268 delegates from 39 countries gathered for the 17th International Silage Conference in Piracicaba, Brazil, held at a renovated sugar mill.  Ground-breaking research premiered at the first 16 conferences covered a multitude of topics, including spoilage, nitrogen utilization, enzymes, fermentation pattern variation among diverse bacterial communities, and environmental changes resulting from silage.  That trend continued this year and stimulated a lot of discussion among attendees.

Ensiling temperatures
With delegates from many climates around the world, the topic of ensiling temperatures was popular.  Highlighted research emphasized that storage in cool (less than 50 degrees F) or warm (above 104 degrees F) temperatures resulted in stunted fermentation, changes in the final volatile fatty acid (VFA) profile, and changes in starch digestibility.

Spoilage
The topic of spoilage was at the forefront of many attendees’ interests.  Researchers ensiled freshly chopped corn, with or without inoculation with spoilage yeasts, simulating the possibility of high yeast counts sometimes found coming off of the field.  Silages were fed fresh from the silo or after exposure to air for 48 hours (actively spoiling).

No effects of inoculation with yeast or aerobic spoilage were reported on intake, but both inoculation and spoilage led to decreases in fat-corrected milk and feed efficiency.  Interestingly, milk fat percentage remained unchanged.  This is especially notable because, anecdotally, some researchers have speculated that spoilage may depress milk fat content.  This researcher was the first to test this theory – and debunk it.

Essential oils
Research on the utilization of essential oils to improve aerobic stability was also presented.  Results showed no improvements with the essential oils tested (carvacrol and thymol).  Furthermore, the research highlighted a negative effect of a reduced lactic acid bacteria population. Thus, researchers concluded that essential oils are not recommended to be added to silages prior to ensiling.

Wet byproducts storage
Minimzing surface area should be the goal for storage of wet byproducts.  Researchers suggested that producers prepare a drive-through concrete trench 3 feet wide, and 3 feet deep to be filled with the byproduct.  Buffered propionic acid should be sprayed on the top before covering with silo plastic.

Treatment with acid is crucial; the byproduct should not be covered without acid application.  In this way, surface area is minimized and the by-product semi-ensiles.  During the fermentation process, carbon dioxide travels to the bottom of the trench, and displaces the oxygen, further preserving aerobic stability.  This speaker also discussed mixing wet and dry byproducts to get an ideal moisture content and preserve aerobic stability.

Overall, the conference was similar to the silos that we all dream of: densely packed.  Other highlights included discussions of experimental inoculants, the effects of silage gasses on global warming and ways to mitigate this, Shredlage^®, a comparison of mean particle particle size versus theoretical length of cut, silage safety, and correlations between silo temperatures and density or inoculant usage.

Click here to access proceedings from the International Silage Conference, including all of the presentations and aforementioned topics.