In agriculture, rain typically poses two major pain points: challenges to field traffic and harvesting timelines. As most of Iowa, Michigan, Minnesota, and Wisconsin are well above long-term average rainfalls this time of year, the Midwest’s 2024 growing season has not only included extreme amounts of moisture but also offered up an unfamiliar complication to many farms: extracellular water. 

“This phenomenon results from rainfall, but also a higher humidity environment,” explains John Goeser, PhD, PAS, and animal nutrition, research, and innovation director for Rock River Laboratory. Simply described as the water outside a plant’s cell walls, excessive extracellular water in forages and feeds promotes microbial growth, feed deterioration, and anti-nutritional factors - including mold, yeast, fungi, or bacteria. 

Beyond the quality issues often associated with forage exposure to rain in the field, extracellular water affects the feed’s aerobic stability and quality, at the feedout stage. “Spoilage yeast and spoilage bacteria will be more likely to grow, and molds are secondary to the yeast and bacteria taking off,” Goeser says. “The more water around, the more likely these bugs are to flourish. Summer offers the perfect scenario as they thrive in warmer temperatures as well.”

Flooded field. Photo courtesy of Rock River Laboratory.

These circumstances can affect any feed stored on the ground and exposed to the elements. “A lot of times we store wet feeds and forages such as corn gluten feeds, distillers grains, premixes, etc. in uncovered piles,” Goeser says. “Anything directly exposed to pooling water or the rainfall can harbor the potential for expedited spoiling and deterioration.”

Goeser goes on to share that this occurrence affects feeds and forages regardless of what preservative product is used on the forage at harvest. Combatting this detriment to ration stability requires management over products. “If we are seeing some digestive upsets in proximity to a rainfall event, unfortunately, there isn’t always a product that will fix it,” Goeser explains. However, he suggests efforts to minimize and combat the feed and forage damages posed by this event. 

“Keep your faces clean and tight, and avoid having piles of feed laying around that can soak up water,” Goeser advises. “Reduce puddles and even large lakes of water from soaking into piles of forage as much as possible.”

Beyond the immediate actions, farms that are curious about what is growing in their feed, or are observing animals experiencing symptoms of poor feed should consider a laboratory enterobacteria assessment. “This tool can be valuable to review the total mixed ration (TMR), or individual forages,” shares Goeser. “Ultimately, it helps gauge how charged the microbial growth is following significant rainfall events.” 

If a dairy is experiencing consistent aerobic stability issues or feed bunk stability issues, then Goeser recommends adding an acid or chemical preservative into the ration - especially in the summer months. Plus, consider targeting the source feed, if it can be identified.

National water prediction service. Photo provided by Rock River Laboratory.

As the flipped weather script for some of the US has required a ‘turn on a dime’ mentality for many farms, water management should be top priority. Its direct effect on animal feed quality can prove challenging and in some cases, serious. Staying proactive and monitoring moisture in and around all stored feeds and forages can become a good habit, even in years when ‘extracellular water’ doesn’t have to be part of the active terminology.