After returning from the market, bread is declared  as old bread and as such was once sold at a certain price (0.013 €) and used as animal feed.  Today, however, this is not allowed,  but it is necessary to heat-treat this type of bread in some way. Namely, the Food Act (NN 18/2023) was passed in Croatia, which does not allow unhealthy animal feed, which includes unused old bread that is returned from the market. Based on the above, the aim of this paper is to thermally  process white, corn and black bread by drying, pelleting, extruding, and getting a new component in animal nutrition. After that, store and determine whether there is an impact of heat treatment on the health of such bread. By monitoring the storage time of old bread types and technological processing on the sample temperature, it can be determined that the sample temperature was significantly influenced by the duration of storage. During the storage process, the moisture content in the samples of old bread varied significantly. The protein content differed  significantly between  the types  of old bread, as well as the method of processing. Microbiological  analysis of processed samples shows that all samples are healthy and can be used as feed.