Improve silage quality for better ROI

An effective silage additive helps to drive fermentation in the right direction, preventing undesirable microbes from robbing valuable protein and energy resources from the ensiled forage.

Improve silage quality for better roiBy DSM Animal Nutrition

Making silage enables the farmer to store forage, providing a cost-effective feed when required. From silage making through to feeding out, the challenge is to ensure that valuable dry matter, energy and protein are not lost.

An effective silage additive helps to drive fermentation in the right direction, preventing undesirable microbes from robbing valuable protein and energy resources from the ensiled forage.

Even the best selection of silage additive cannot replace getting the fundamentals of silage making right.

A wide variety of silage inoculants are available on the market. These can be broadly grouped into 3 different categories.
• Bacteria
• Preservatives or organic acids
• Enzymes

Most silage inoculants are lactic acid bacteria (LAB). Some products contain only homofermentative strains or heterofermentative strains while others are a combination of both types of LAB.

Homofermentative bacteria such as Lactobacillus plantarum, Pediococcus, Enterococcus and Lactococcus enhance the production of lactic acid, which lead to a faster drop in pH value and improved fermentation, thus reducing DM losses, protein breakdown and growth of undesirable microorganisms.

Heterofermentative bacteria such as Lactobacillus brevis, L. kefiri and L. buchneri convert forage sugars to lactic and acetic acid. The production of acetic acid will improve aerobic stability of the silage by preventing proliferation of undesirable yeast and mold keeping silage highly nutrient and hygienic.

In grass silage, the main challenge is acidification—in which case an adequate amount of homofermentative lactic acid bacteria (LAB) should be applied. A combination of homo- and heterofermentative lactic acid bacteria guarantees not only optimal fermentation but also enhanced aerobic stability.

Application of inoculant bacteria
Silage inoculants are generally applied as the forage is being picked-up or baled, using a specific applicator. While the forage will already have a range of naturally occurring bacteria on them including lactic acid bacteria species, the microbial community present may not drive optimum fermentation and may even have high levels of detrimental bacteria.

The aim with an inoculant is to supply a sufficient amount of selected strains with known effects on fermentation to help ensure that fermentation proceeds rapidly and in the right direction.

The rate of 100 000 (1 x 105) colony forming units (cfu) per gram of fresh forage will provide enough microorganisms to dominate fermentation. If a silage inoculant has a lower level than this, or does not even specify a cfu count, then there may be insufficient bacteria to really influence silage fermentation in positive way.

Be aware that not all inoculant bacteria are equal. Even within the same species, there is wide variation in what effect the bacteria will have on fermentation. Products and the published evidence of efficacy should specify the actual strain numbers to provide assurance to customers.

Quality of the packaging and storage conditions are also important. These should prevent exposure to oxygen, moisture and heat that could reduce the viability of bacteria. Follow manufacturer instructions on storage and use and ensure that application is even and comprehensive over the whole forage.

The use of organic acids such as propionic and formic acids are aimed at lowering the silage pH to make it less favorable for undesirable bacteria such as Clostridia. Other organic acids and their salts including potassium sorbate and sodium benzoate target the growth of yeasts and mold fungi either in fermentation or during feed out.

There needs to be sufficient amount of the additive to provide a concentration in the bulk forage that will actually be sufficient effect on the growth of those undesirable organisms. That rate is typically at 5 to 10 kg of active ingredient per ton of forage to preserve the silage or around 1 to 2.5 kg/ton to restrict yeast amount at feed out. Compare those values to what is actually contained in a product that claim a preserving affect.

At the lower inclusion rate (less than 5 kg/ton of active ingredient), organic acids do not provide full preservation. To ensure adequate fermentation it is advisable to use silage inoculants. Bear in mind that organic acids and silage inoculants cannot be mixed together.

The aim of adding enzymes to silage is usually to aid the breakdown of plant cell walls (e.g. use of celluloses and hemi-celluloses). The main benefit of this appears to be an increase in the amount of sugars available for LAB bacteria to convert to lactic acid for more rapid acidification.

While there is some evidence of favorable outcomes of this on silage quality and animal production this is less reliable than general silage inoculant approach. In some cases, there are claims of increasing forage digestibility for livestock but evidence for this is less clear. There are also some enzymes aimed at improving starch availability for either bacteria or livestock but research on this is still at an early stage.

Kung, L., 1998. A review on silage additives and enzymes. Proc. 59th Minneapolis Nut. Conf. (pp. 121-135).
Kung, L., 2001. Silage fermentation and additives. Sci. and Tech. in the Feed Ind., 17, pp.145-159.
Muck et al., 2018. Silage review: Recent advances and future uses of silage additives. J. Dairy Sci. 101(5): 3980-4000.

1. Acosta-Aragon, Y., Jatkauskas, J. and Vrotniakiene, V., 2012. The effect of a silage inoculant on silage quality, aerobic stability and milk production. Iranian Journal of Applied Animal Science, 2(4), pp.337-342.
2. Aragón, Y.A., 2012. The use of probiotic strains as silage inoculants. In Probiotics in Animals. IntechOpen.
3. Aragón, Y.A., Stadlhofer, J., Schoendorfer, K., Pasteiner, S., Schatzmayr, G., Klimitsch, F.,
4. Kreici, G. and Boeck, G 2010, The use of a silage inoculant in silages of grains of Pisum sativum. Biotechnology in Animal Husbandry 26 (spec.issue), p 451-456.
5. Aragón, Y.A., Stadlhofer, J., Schoendorfer, K., Pasteiner, S., Schatzmayr, G., Klimitsch, F., Kreici, G. and Boeck, G 2010, The use of a silage inoculant in silages of grains of field bean (Vicia faba). Biotechnology in Animal Husbandry 26 (spec.issue), p 451-456.
6. Kesselring, J., Boeck, G., Schoendorfer, K., Hoeger, T. and Schatzmayr, G., Silage fermentation quality in grass silages inoculated with Lactobacillus kefiri alone and a formulation containing L. kefiri. In 15. BOKU-Symposium Tierernährung 129-132.
7. Jatkauskas, J. and Vrotniakienė, V., 2011. Effect of lactic acid bacteria inoculant on fermentation quality and aerobic stability of legume-grass silage. Gyvulininkystė: Mokslo Darbai (Animal Husbandry: Scientific Articles), (57), pp.28-39.
8. Jatkauskas, J., Vrotniakiene, V. and Aragón, Y.A., 2010. Fermentation quality and nutritive value of grass-legume silage treated with inoculant BioStabil Plus. 14th Intl. Symp. Forage Cons. 45-47.
9. Rodríguez AA, Acosta Y, Rivera V, Randel PF. Effect of a microbial inoculant on fermentation characteristics, aerobic stability, intake, and digestibility of corn silage by rams. Rev Colomb Cienc Pecu 2016; 29:108-118.
10. Rodriguez AA, Acosta-Aragon Y, Valencia E. Biomin Biostabil Mays enhanced the fermentation and the aerobic stability of corn silage under tropical laboratory conditions. J Anim Sci 2009; 87, E-Suppl. 424.
11. Schöndorfer, K., Aragón, A.Y., Klimitsch, A. and Schatzmayr, G., 2010. Effect of Biostabil Mays on aerobic stability of corn silages. In Conference Proceedings, 14th International Symposium Forage Conservation, Brno, Czech Republic, 17-19 March, 2010 (pp. 152-153).
12. Vrotniakiene, V., Jatkauskas, J., Schnyder, H., Isselstein, J., Taube, F. and Auerswald, K., 2010. Fermentation quality and dry matter losses of grass-legume silage treated with lactic acid bacteria mixture. In: Grassland in a changing world, p.575 – 577.
13. Zwielehner, J., Jatkauskas, J. and Vrotnikiene, V., Silage fermentation quality in whole plant maize inoculated with a novel formulation of a biological inoculant with the recently EU-authorized Lactobacillus kefiri. In 13. BOKU-Symposium Tierernährung, p. 259-263.