Out of all the forage a farmer harvests, a portion of it never makes it to the cow. This is also known as shrink, a popular topic of discussion that has surfaced within the last decade. In a Forage Focus newsletter article, University of Wisconsin-Madison extension specialist Luiz Ferraretto highlighted strategies to help reduce the amount of shrink as we progress into silage season.
Shrink varies from farm to farm and can also be defined as dry matter loss. Nutritive value can be compromised while the risk of undesirable microorganisms, such as molds and yeasts, rises. Nutritive value and dry matter loss begins the moment the plant is harvested and continues up until feeding. Although some dry matter loss can be avoided, there are also some factors that make loss unavoidable. “Plant respiration and aerobic fermentation use up remaining oxygen in the silo after sealing, and bacteria use water soluble carbohydrates during anaerobic silage fermentation. Both are unavoidable losses since these processes are essential for silage preservation,” said the extension specialist.
After silage is harvested, silage fermentation begins. Enterobacteria and yeast reach oxygen first before lactic acid fermentation starts. Proper packing procedures shorten the aerobic phase. In doing so, anerobic fermentation can begin, which will preserve the value of the forage that the farmer desires. “Adequate layer thickness while packing, tractor weight, delivery rate, and harvesting forages at the appropriate length of cut and dry matter can help reduce silo porosity,” noted Ferraretto.
Because the pile will be exposed to the elements, it is important to cover the surface to enhance the fermentation process. Many use plastic to cover piles, including a popular option of using a plastic that includes a second layer of film. This film suctions itself to the surface of the pile, preventing oxygen from entering. Many farmers have seen better preservation results with the use of films.
Although using plastic to cover the pile is a common practice, plastic is not bulletproof. Tears and holes from weather, animals, or happenstance can make an appearance, causing oxygen to infiltrate the surface. It can be easy to forget about unopened silos, so be sure to check often for damage so no feed will be compromised.
Upon opening, silage is immediately greeted by a flow of oxygen. This can cause aerobic microorganism growth and deterioration. “Oxygen penetrates 35 inches a day in the silo, regardless of how well packed and preserved the silo is. Usually, aerobic deterioration is followed by an increase in temperature and mold activity. Aerobic deterioration represents a loss of nutrients and end products of this deterioration could adversely affect herd health,” warned Ferraretto.
A slow removal rate, uneven silo face, and plastic removed too far ahead of time will allow the forage to be exposed to oxygen at a fast pace. Avoid this oxygen infiltration to keep your forage quality at its best.
