Making high-quality forages requires a long list of decisions to get it from the seed to the feedbunk. One of those choices that needs to be made around harvest time is what inoculant to use.

Inoculants are selected types of bacteria that are added to silage during harvest, according to Luiz Ferraretto, an assistant professor and extension specialist at the University of Wisconsin-Madison. These bacteria can proliferate faster than natural bacteria and produce specific types of acid desired during the fermentation process.

“We use inoculants to modulate and make fermentation faster to ensure that we protect the silage investment by having the specific fermentation we want and as fast as possible,” said Ferraretto during an episode of the Hoard’s Dairyman “Herd It Here” podcast.

The best inoculant to purchase depends on the true needs of each operation, Ferraretto noted. The two most common types of inoculants are homofermentative and heterofermentative.

Homofermentative inoculants contain bacteria that produce primarily lactic acid. They accumulate lactic acid quickly at the beginning of fermentation, Ferraretto said, to help feed reach a low pH state to control undesirable microorganism proliferation.

Heterofermentative inoculants produce lactic acid as well, but they also have bacteria that shift toward production of acetic acid, which is important in maintaining aerobic stability during the feed-out phase. Acetic acid inhibits yeasts and molds from proliferating and deteriorating the silage, he noted.

If a farm has issues with delayed fermentation and forages not reaching the ideal pH, a homofermentative inoculant is the way to go, Ferraretto said. This is commonly a good fit for alfalfa, which contains more protein and therefore produces more ammonia, which buffers fermentation. “Having an inoculant that drops pH very fast is quite useful in this situation,” explained Ferraretto.

Other crops such as corn silage, high-moisture corn, earlage, and snaplage may ferment well but be less stable at feedout. This is where a heterofermentative inoculant should be considered.

In any situation, Ferraretto emphasized the importance of selecting products that are backed by third-party research. Also look for results that are consistent, which would suggest the product would work more consistently on farm. Ferraretto cautioned against choosing a product on price alone and reiterated the need for research to prove its effectiveness.

Ferraretto said inoclulants are important to dairy cattle because they help produce high-quality feed, but they are only one piece of the puzzle. “Inoculants are only one part of the process,” he reminded. “They are important and helpful, but if you don’t do everything else well, the likelihood of them working is reduced.” To learn more from Ferraretto on inoculants and making quality forages, listen to the most recent episode of the “Herd It Here” podcast, titled “The role of inoculants in quality forages.” This episode was sponsored by Bonsilage.