Management key for reducing silage losses

MADISON, Wis. — Silage management is key to providing high-quality feed for dairy herds.

“A perfect scenario is we ensile all the material we need, we remove all the oxygen, we seal it properly and then fermentation begins,” said Luiz Ferraretto, associate professor in the Department of Animal and Dairy Sciences at the University of Wisconsin-Madison.

“Then the bacteria utilize the sugars to generate a combination of lactic acid and acetic acid which should result in a drop in pH to about 4 to get to the stable phase,” said Ferraretto during a webinar hosted by Hoard’s Dairyman.

“But we know there are a lot of potential losses,” he said. “Unavoidable losses can range from 5% to 15% and avoidable losses can be from zero to 26%.”

The more silage losses there are, the university professor said, the more expensive each unit of silage fed gets.

Avoidable losses, Ferraretto said, are usually related to undesired microorganisms.

“We also have deterioration during storage and this will occur if you have any sort of hole in the plastic covering or any kind of puncture in a silo bag,” he said.

There is also aerobic deterioration of the silage after storage.

“I know you have to open the silage to feed your cows,” the professor said. “But the real question is how to minimize this process that is usually associated with yeast and molds.”

The fermentation process is very complex, said Ferraretto, who is also the UW-Madison Extension specialist for rumen nutrition.

“We want to see lactic acid production and hopefully we won’t have any propionic or butyric acids,” he said.

“Ethanol is one of the main fermentation end products associated with yeasts,” the specialist said. “So, obviously, we don’t want a lot of ethanol in silage because we don’t want yeast to be utilizing any of the substrates.”

The amount of yeast in silage will vary from very low to very high at different dairy farms.

“We cannot easily predict the yeast load for a given dairy because of a combination of different factors,” Ferraretto said. “They may be weather related that we have no control over or it could be related to disease pressure or management factors associated with silage making.”

The university professor talked about a study that evaluated the impacts of exposing silage to air.

“There is a very strong relationship between yeast counts in silage and a drop in milk production in dairy cows,” he said. “The reasons for that are lack of palatability and drops in intake.”

One way to reduce the production of yeast and molds during fermentation is to use L. buchneri.

“Early in the fermentation, it focuses on lactic acid, but at a certain point it focuses on acetic acid,” Ferraretto said. “That is important because acetic acid can inhibit the proliferation of yeast, molds and other undesired bacteria at feed out.”

There are some myths about L. buchneri such as it takes a minimum of 60 days for the inoculant to work.

“That is not true, the response is much more evident after 45 to 60 days,” Ferraretto said. “But the response can occur as early as seven to 30 days.”

L. buchneri delays the process, the professor said, but it does not necessarily kill the yeast and molds.

“Otherwise, you could leave the silo open forever and nothing would happen with the silage,” he said.

Although silage inoculants can help, Ferraretto said, management will always be key to producing a high-quality product.

“If you decide to use inoculants, they vary a lot in prices, strengths and counts,” the specialist said. “They may not work exactly the same way in different conditions, so make sure you choose something that has a lot of research data.”

“The feed-out management has to be really good to help minimize the issue because air penetrates into the silage mass very fast no matter how well it is packed,” he said. “You have to remove enough material to prevent heating and spoilage.”

If possible, dairymen should not remove feed more than one to two hours prior to feeding.

“The earlier you take the feed out, the more time you give to the yeast and molds to start the process,” Ferraretto said.

“Check silo bags for holes and close them as soon as you can to avoid potential deterioration during fermentation,” he said.

Harvest silage at the proper maturity, Ferraretto said.

“I know this is a difficult decision because we need to have optimal dry matter concentrations,” he said. “If it is too wet, you might have a lot of loss of nutrients, but if it is too dry, fermentation and packing will not be good.”

One thing that plays a major role with microorganisms is dirt.

“In very dry years there is a lot of dust. When it is too wet there can be a lot of mud contamination,” Ferraretto said.

“Yeast contamination is something we are seeing more and more in corn silage, so I think we need more research to understand that,” he said. “But we know they create major challenges for fermentation, nutrient value and consequently with performance.”