There were also drought conditions through Kansas and parts of the Central Plains. Forage growers from the Midwest through the Northeast experienced average to strong heat units and growing conditions early but then recognized a total of 40 to 80 inches of rain on the year through Oct. 1 (weather data accessed at water.weather.gov/precip; considerably greater than normal).
The rainfall, a more mature crop, delayed harvest and new fungal plant pathogens changed our expectations in a matter of a few weeks for the eastern U.S. Now the silage crop is in storage, many are opening up this feed and experiencing different outcomes with this year’s crop relative to the past. The focus here is to raise awareness about what this year’s silage may have in store and put you in position to make quick and effective decisions to stave off feed hygiene and performance issues later on.
For those with ideal dry matter (DM) and crop maturity (half milk-layer kernel maturity and 35 percent DM), you’ve avoided the fray. For many though, environmental conditions during the growing and harvest season, along with excessive plant drydown with heavier plant disease in some areas, came together and contributed toward forage producers being stuck harvesting a drier and more mature corn silage crop. Corn silage samples from the Midwest and eastern U.S. are now averaging around 40 percent DM through Rock River Laboratory (Figure 1).
There are nutrition quality and mycotoxin considerations with 2018 silage; however, the crop maturity and dry matter should be the No. 1 nutrition aspect to be aware of when opening the silo. Again, Mother Nature and conditions beyond our control contributed to the drier silage. This quality issue is widespread, and you are not alone if your silage is drier than you’d like; many are in the same situation.
Heavy wild yeast load
The No. 2 concern I have around this year’s silage, in concert with crop dry matter, is the wild yeast load. Epiphytic (wild) yeast in forage is known to lead to silage deterioration and initiate a cascade of further hygiene and quality issues, such as mold and negative bacterial growth. This is a real challenge for many dairies and goes under-recognized for many farms because we can’t “see” yeast growth like we do with molds. Wild yeast has also been shown to alter rumen metabolism and negatively affect fiber digestion.
Forage labs measure yeast colony numbers (colony-forming unit; CFU) per gram of forage. To put this in perspective, grab the top knuckle of your pinkie and recognize the top of your finger is about the same volume as a gram of forage or TMR. Rock River Laboratory feed samples assessed over the past several years have stepped up in yeast counts, which I’ve discussed during feed hygiene talks and meetings (data not shown).
This year has compounded the issue with heavy rainfall. Learning from Chris Rhoden and Keith Bryan, technical services with Chr. Hansen, increased water activity contributes to greater microbial growth. Rock River Laboratory now routinely measures yeast loads at 100,000 CFUs or more per gram of feed. In light of the historic rainfall experienced through many regions prior to and during harvest 2018, the increased yeast load showcased in Figure 2 makes more sense.
Control your outcome
Given the need to sharpen our pencils and find alternative ways to improve balance sheets, feed conversion efficiency is a renewed focus. On this note, feeding your herd a clean TMR is a must. Dirty feed (i.e., heavy yeast load) disrupts rumen digestion, metabolism and can lead to cows spending energy fighting negative feed-borne microbes instead of diverting that energy to performance. With my No. 1 and No. 2 2018 silage concerns in mind, assess and take control of your silage.
Aggressively manage silage quality upon feedout. If possible, feed 12 inches or more per day to limit aerobic exposure. If this isn’t possible, consider splitting bunkers or piles in half to feed more depth per day from a smaller face. In discussion with George Jarrett recently, he shared experience in commenting that heavily applying preservative acids on exposed silage faces (i.e., exposed sides) helps maintain clean feed when splitting.
If yeast loads continually measure 100,000 to 1 million CFU per gram or more despite aggressive management, mix unloaded or defaced silage with 5 to 10 pounds preservative acid per ton to knock yeast loads back and avoid negatively inoculating the TMR. This may seem like a lot or expensive, but it’s cheaper than applying these rates to the whole TMR and 5 pounds per ton only equates to 0.7 percent acid on a DM basis. This amount is tiny relative to a successfully fermented silage acid load.
Bring your veterinarian, nutrition consultant and feeder together to assess potential dry matter and yeast aspects of your silage and take proactive steps that will benefit your bottom line. While the silage quality may seem like more bad news during continued economically challenging times, your team can control how this silage feeds and improve feed conversion potential.
John Goeser earned a Ph.D. in animal nutrition from the University of Wisconsin – Madison, where he currently serves as an adjunct professor in the dairy science department. He also directs animal nutrition, research and innovation efforts at Rock River Lab Inc. based in Watertown, Wisconsin.
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- Director of Nutrition, Research and Innovation
- Rock River Laboratory Inc.
- Email John Goeser