Bacteriological quality of wrapped round bales. Control of contaminations

摘要

The technique of bale wrapping has been developing to a large extent in the regions of medium altitude. Due to inherent bacteriological and sanitary risks, it comes up against the present trend of moving local milk transformation increasingly towards produce with identifiable regional characteristics and based on so-called traditional feeding. The first part deals with the present theoretical and practical knowledge regarding the two bacteria that are particularly involved : Clostridium tyrobutyricum and Listeria rnonocytogenes. The second part shows the results of a study where farms of the Rhone-Alps region were monitored; the controlling factors of these two agents were analysed. Contamination by C. tyrobutyricum is very small when the dry matter content is above 50%; the use of additives, conditioning, teddings are beneficial too. L. monocytogenes develops preferably in the parts of bales that are spoilt by oxygenation, where the pH is Iow, and all the more so as the DM content is lower. Contamination of the wrapping does not appear to depend on that of the fresh forage. Lastly, practical advice is given on how to avoid the contamination of bales.