The aim of preservation is a longer storage life of feed and thus avoid their degradation that takes place unwanted amplification of undesirable microorganisms. Microorganisms which cause spoilage of fresh or preserved fodder has typically not themselves pathogenic for animals, but may produce dangerous substances (toxins, amines). The amount of the of losses is directly proportional to the quality of silage. The best analyzer is an animal. Reduced performance, difficulties with the health status or loss in the form of feed remains suggests a poorly prepared ration, but mainly about the feed that could be produced in better quality and lower losses.