Inoculants can boost fermentation

To custom forage harvester Greg Callen, of Twin Falls, ID, putting up silage without an inoculant is like making a BLT sandwich without mayonnaise. In both cases, you still end up with the basic product, but an important component is missing.

"Inoculants help us make a better product for our customers," says Callen, who has been using various inoculant products for nearly a decade. "There's all kinds of research showing that using an inoculant gives you better fermentation. You have less dry matter loss and preserve more nutrients."

Large drylot dairies (1,000 cows and up) make up the customer base for Callen's Southern Idaho Forage Harvesters. He chops about 4,000 acres of alfalfa haylage per cutting (five cuttings per year, on average) and also puts up about 85,000 tons of corn silage. Roughly 85% of the haylage and 15% of the corn silage go into silage bags.

All three of Callen's self-propelled forage choppers are set up to apply dry inoculant products through the blower at chopping. He leaves individual product choice up to the customer.

"Some of our customers using bags can get a little break on cost if they buy the inoculant through the (bag) dealer," Callen explains. "Otherwise, we provide a Pioneer product and add a charge of about 10 cents per ton for our handling."

While nearly all of his haylage customers opt to use inoculants, only 80% of his corn silage customers choose to do so. "Some people aren't convinced that inoculants are as effective with corn silage," Callen points out. "We leave the decision up to the customer."

Richard Muck of the U.S. Dairy Forage Research Center in Madison, WI, says there is some evidence that inoculants are less successful when used with corn silage. In a recent survey of existing silage inoculant research, he found that inoculant treatments led to fermentation improvements approximately two-thirds of the time in hay-crop silages, but only about 40% of the time in corn silage.

The reduced response is linked to the natural population of lactic acid bacteria in a crop, Muck says. On average, the natural population of these bacteria on corn at ensiling is about 10 times higher than the natural population on alfalfa.

"That makes it difficult for the inoculant to overwhelm the natural bacteria on corn silage and produce an effect," he says.

Also, natural fermentations in corn silage tend to be high in lactic acid, low in acetic acid and result in a low pH. "With such a good fermentation, it's just difficult for an inoculant to make substantial improvements," explains Muck.

For those reasons, he believes the best time to use an inoculant for corn silage is when a crop is overly dry or immediately after a killing frost. "The limited research data suggest that these are conditions where the natural population may be lower and/or less competitive than the inoculant bacteria."

For hay-crop silages, Muck recommends focusing on wilting conditions. In general, inoculants will be most successful when wilting times are one day or less, and least successful when wilting takes three or more days.

Some other things to mull over if you're considering using silage inoculants:

* Application rates. There's a lot of variability in the labeling of inoculants, making product comparisons difficult.

One major consideration, according to Muck, is the number of lactic acid bacteria applied per unit of crop. He recommends using a product that applies at least 90 billion live lactic acid bacteria per ton of crop (as fed) or 100,000 per gram of crop.

* Strains and species. Inoculants contain one or more strains of lactic acid bacteria. Some strains may grow better than others under drier conditions, higher temperatures, etc. Because of these differences, it's important to use products labeled for the crop that you're ensiling (i.e., if a product is labeled only for corn silage, don't use it on alfalfa and vice versa).

"Don't be shy about asking the dealer for independent research data to back up product claims," advises Muck.

* Liquid vs. dry products. Both types of products can get the job done. But Muck gives a slight edge to liquid inoculants for these reasons:

1) Liquid products, sprayed on at the chopper, generally allow for a more uniform application.

2) Liquid products tend to begin working faster since they don't need to be moistened by plant juices before they start growing.

3) It's relatively easy to keep the small packets of liquid product cool and dry (necessary for maintaining bacterial activity) by storing them in a refrigerator.

If you do opt to use liquid products, be sure the water for dilution has a chlorine concentration of less than 1 ppm. "Chlorine can kill lactic acid bacteria," explains Muck.

If you have water with high chlorine levels, look for an inoculant product containing compounds that can neutralize the chlorine. Also remember that once a product has been diluted, you generally need to use it up within a 24-hour period.