Advanced technology is all around us, making our lives easier. Advances in silage technology, which include high-capacity precision-chop harvesters, improved silos, polyethylene sheeting, shear-cutting silage unloaders and total mixed rations, have made silage an important method of forage preservation for beef and dairy cattle producers.
Silage quality and nutritional value are influenced by numerous biological and technological factors, including the crop species, stage of maturity and dry matter (DM) content at harvest; chop length; type of silo; rate of filling; forage density after packing; sealing technique; feedout rate; weather conditions at harvest and feedout; additive use; timeliness of the silage-making activities; and the training of personnel. Because many of these are interrelated, it is difficult to discuss their significance individually. However, there are two dominant features of every silage:
- The crop, including its stage of maturity and its “ensilability”
- The management and know-how imposed by the silage maker
In “perfect” silage, available carbohydrates are converted by anaerobic bacteria (mainly “homofermentative” lactic acid bacteria) to lactic acid. That lowers the pH rapidly and preserves the silage. In even the best of circumstances, some DM is lost during lactic acid production. But the ensiling process is seldom perfect. Whenever oxygen is present, carbohydrates are converted to carbon dioxide and water, accompanied by the generation of considerable heat. The results are serious DM losses.
Additives can be divided into three general categories:
- Fermentation stimulants, such as bacterial inoculants and enzymes
- Fermentation inhibitors, such as propionic, formic and sulfuric acids
- Substrate or nutrient sources, such as molasses, urea and anhydrous ammonia
Perhaps no other area of silage management has received as much attention among both researchers and livestock producers in recent years as bacterial inoculants. Effective bacterial inoculants promote a faster and more efficient fermentation of the ensiled crop, which increases both the quantity and quality of the silage. The bacteria in commercial products include one or more of the following species: Lactobacillus plantarum or other Lactobacillus species, various Pediococcus species and Enterococcus faecium.
These strains of LAB have been isolated from silage crops or silages and were selected for two reasons:
- They are homofermentative (i.e., ferment sugars predominantly to lactic acid)
- They rapidly grow under a wide range of temperature and moisture conditions
Bacterial inoculants have inherent advantages over other additives, including low cost, safety in handling, a low application rate per ton of chopped forage, and no residues or environmental problems.
Enzymes are capable of degrading plant cell walls and starch, which could provide additional sugars for fermentation to lactic acid and increase the nutritive value of the ensiled material. Although enzymes offer potential to improve silage quality, considerable work needs to be done before they will become commonly used additives.
Original article written by Kansas State University Ph.D. Emeritus Professor, Keith Bolsen.