Finding ways to improve forage quality and harvesting methods has been a focus of several research projects by Wayne Coblentz, USDA-ARS research dairy scientist. He’s studied the effects of adding propionic acid-based preservatives to forages to reduce spontaneous heating, which can result in possible combustion, dry matter losses, and lower forage quality. He also works to answer farmer questions on the efficacy of applying manure on alfalfa.
Comparing the quality of forage bales wrapped with twine, net wrap, or B-Wrap® after they’ve been stored outside was the objective of recent research conducted by Krishona Martinson, University of Minnesota Extension specialist.
Both scientists gained forage research funds through the Midwest Forage Research Program (MFRP) administered by the Midwest Forage Association, which represents forage producers and users as well as educators and industry. “Grant funding is incredibly important to the scientific and agricultural communities, and MFA funding helps advance our understanding of forages,” Martinson says. “Every dollar that you can find from an outside source, particularly to address forage-related problems, is very much appreciated,” adds Coblentz.
Coblentz had earlier experimented with propionic acid-based preservatives as an option in handling hay bales that had to be put up too wet, but results were inconsistent from one trial to the next. Armed with MFRP funds, he found that bale diameter did influence preservative effectiveness. As bale packages have increased in size, they’ve become more sensitive to spontaneousheating. Results, once again, were varied. “Do preservatives work? Yes. We have observed situations when these products have worked well. Do they always work the same way? No. Every situation is a bit different, but there are trends we picked up in these studies,” he explains.
“First, there is almost always a measurable response to product application during the first 30-40 days of storage,” he says. Secondly, months after baling, moisture concentration in propionic acid-treated bales will always be greater than observed in untreated bales. In addition, when those products are less effective, treated bales will run what Coblentz calls a low-grade fever after 30-40 days in storage. Internal bale temperature in treated bales after that point is often higher than in control bales and may last a month or longer. That suggests continuing microbial activity in those bales and continuing deterioration of nutritive value.
Coblentz also observed that treated silage bales, once exposed to air for feeding, had a longer shelf life than untreated bales. “Does that mean all silage bales should be treated with these products? No. But if an extended period of exposure is likely before you are able to use that material, that’s a really nice tool to have in your toolbox,” he says.
One of Coblentz’ earlier MFRP projects compared wrapped silage bales from alfalfa field plots with no manure applied, with dairy manure applied to stubble right after harvest, and with manure applied one or two weeks after harvest. It showed elevated clostridial counts on silage when manure was applied to alfalfa during a growth cycle, which can adversely affect silage fermentation and quality. “When you apply manure on alfalfa stubble, clostridial counts tend to be lower compared to later applications,” he says. “We were able to show there is a clear risk associated with putting manure on growing alfalfa.”
This year, with additional MFRP funding, Coblentz will study how dairy manure affects fermentation and nutritive value of alfalfa-grass silage round bales and how to reduce clostridial issues by field wilting and/or using inoculants. Baled silage doesn’t ferment the same way as precision-chopped silages stored in silos, ideally at less than 70% moisture. When alfalfa is baled and wrapped in plastic at greater than the recommended 45-55% moisture range, closer to 55-60%, “you’ll start to pick up clostridial products such as butyric acid and ammonia,” Coblentz says. “Baled silages are more sensitive for a whole host of reasons to the formation of clostridial products than might be the case with other forages and/or modes of harvest storage.”
Martinson’s 2018 MFRP research compared plastic twine, net wrap, and B-Wrap, a breathable bale wrap used with newer John Deere balers, on alfalfa round bales. Stored outside for more than 180 days, B-Wrap bales had lower mold counts and greater dry matter preservation as compared to bales bound with twine or net wrap and stored the same amount of time, she says. B-Wrap technology allows bale moisture to escape yet shields hay from precipitation.
The cost of B-Wrap, $8.33/bale, is much higher than $1.17/bale for net wrap and $1/bale for twine. “But the economics speak for themselves; B-Wrap does a better job at preserving quality by repelling moisture,” Martinson says. “If you’re going to store hay for 90 days or less, it doesn’t matter what wrap type you use. But if you are storing hay for more than 90 days, B-Wrap is going to pay for itself.”
After one year in outdoor storage, twine- and net-wrapped bales showed moisture concentrations up to 27% with dry matter losses of 7% and 5%, respectively. Moisture and dry-matter levels of B-Wrap bales didn’t change throughout the storage period. Nonstructural carbohydrates, NDF digestibility at 48 hours, and RFV were greater in B-Wrap bales compared to twine bales; forage quality of net-wrapped bales was intermediate between the other wraps.
Martinson recommends farmers use net wrap on hay to be fed within 90 days of harvest and B-Wrap for bales stored 180 days or longer when indoor storage isn’t possible.
Bales were stored on pallets to prevent them from freezing to the ground and damaging wrap or bales. “No matter the wrap type, the wastage or weathering of hay did not exceed 6”, she says. “That’s a testament to technology and the ability to make a firmer, denser bale that repels moisture as well as to the importance of storing hay on the pallets.”
MFA awards research funding to forage-related projects in the Upper Midwest, choosing projects that help increase profitability and productivity to the industry. But it does more than grant seed money for important research, says Coblentz.
“The Midwest Forage Association also provides a good outlet for research findings and is a really good conduit to the public,” he says. Both researchers regularly contribute to MFA’s Forage Focus publication, a member-only quarterly magazine devoted to the latest forage-related research. They also frequently speak at the Symposium, a winter event combining educational seminars, industry exhibits, and many opportunities for networking hosted by MFA and related organizations.
Other membership benefits include Clippings, a monthly e-newsletter offering timely forage news; money-saving coupons; discounts to MFA events; a member-only database of research articles; and membership to the National Alfalfa & Forage Alliance (NAFA). NAFA keeps alfalfa in the forefront, for example, gaining mention of the crop in the farm bill which resulted in millions of dollars annually of federal research funding. NAFA also established the Alfalfa Checkoff program, adding additional forage research dollars, and hosts the Alfalfa Intensive Training Seminar, an educational program attracting participants worldwide. But research funding, education, and networking opportunities wouldn’t happen without farmer and industry memberships, which only cost $50/person. For more on the association, visit midwestforage.org; for membership information, visit midwestforage.org/membership.php.