Dokumentation av ensilering med fokus på clostridiesporer i mjölk

Sammanfattning: To produce milk of good standard the feed for the animals kept for milk production is an important part in the work of quality. This makes it important to feed them with good forage, especially when feeding with silage. The process of making silage is very complex and requires a careful handling to be successful. The fundamental idea is to create an anaerobic environment in the herbage to favour the desirable micro-organisms, in this case the lactic acid bacteria. This environment is created by careful handlings were the importance is to pack the crop well and cover it as soon as possible to exclude oxygen. If this succeeds, the chances of getting good forage that fulfils all requirements for a good hygienic quality are very good. It also minimizes the risk that the feed affects the dairy products in a negative way. It is particularly during the stable season that spores of clostridium causes quality problems. Those spores can be brought in during harvest and thrives in the anaerobic environment that appears during ensiling. The environment in the milk that is used for making some hard cheeses please the clostridium spores to arise. The spores produce hydrogen gas and carbon dioxide that will destroy the texture of the cheese. The dairies want to avoid this quality problem and therefore Arla among other dairies have introduced a system that gives reduction to the producers that deliver milk with high contents of spores. During the season 05/06 it appeared that more milk deliverers of Arla showed higher levels of spores than normal in their delivered milk. Therefore a project were started to examine the cause of the problem. This master thesis is made as a part of this project and the main task has been to put together an inquiry that mainly brought up questions about harvesting and storage of grass and other forage. 143 farmers that delivered milk with high levels of spores answered the inquiry. 24 farmers with really high levels were selected from this group. To be able to compare these results 20 other farms were picked out as a reference group. This group also had to answer the inquiry. A sample from the manure storage was taken at each farm in the compared groups. This sample was used in the study and would represent the total amount of spores of the farm during the season 05/06. The results of the study showed that a majority of the farms had used round bales as storage system for their silage and that the moisture content of the forage was above what is recommended. The majority of the farmers spread slurry as manure on their fields. Most of them wilted their herbage before loading and about one third had engaged a machine station to help them with their harvest. Many of those in the group that had problems this season also have had problem earlier years. Compared to the group with high spore levels the distribution between tube spreading and wide spreading the manure was much more even in the reference group. In the latter group it was more common to wide spread. There was a tendency that within the reference group more farmers had chosen to use additives to maintain a high-quality ensiling. By the analysis of the manure one could see that the reference group had lower levels of spores then the others and even if they had relatively high levels in heir manure they were able to deliver milk that were free from spores.