Enzymes in silage inoculants are primarily used to generate sugars for the inoculant bacteria to use for growth and fermentation. Enzymes essentially provide fuel for the bacteria to drive a fast, effective forage fermentation.
In addition to fueling bacteria, some enzymes have been shown to provide positive effects on silage digestibility. Studies have shown improvements in neutral detergent fiber (NDF) digestibility1 and increased digestion in rumen fluid2 due to specific enzyme activity. Using specific, targeted enzymes can help make fiber in the plant more accessible in the rumen. However, some enzymes may break down the cellulose itself, which steals energy from cattle and can increase the risk of runoff and associated dry matter losses.
Two things dictate total enzyme activity in the silage environment: the amount of active enzyme present and the time in contact with the forage. In silage, enzymes have a long contact time — often several months. Plus, the acidic conditions in silage are near optimal, allowing enzymes to work at a high rate. Therefore, a little bit of enzyme can go a long way.
Producers should look for an enzyme activity guarantee on the inoculant product label. Guaranteed levels of enzymes should be declared, and they should be the same as those used in trials to validate product efficacy. If guaranteed levels are not given for enzymes, it"s best to assume they aren"t present, even if enzyme sources are listed in the ingredients.
As with microorganisms, there is a list of enzymes and sources approved by Association of American Feed Control Officials (AAFCO) for use in animal feeding. Be aware that, for some people, certain enzymes can be allergens. Therefore, it"s important to handle products containing enzymes carefully. Producers should do so in a well-ventilated area, wear gloves and avoid inhaling product particles or dust.
1 Kung. Effect of Enzymes on the Fermentation and NDF Digestion of Corn Silage. Unpublished. 2010
2 Davies, Z. S. et al., Animal Feed Science and Technology 83 (2000) 205-221