A magnetic body includes a plurality of laminated inner layers and an insulating enclosure fully enclosing the inner layers therein. The walls defining the fluid passages comprise a flexible and thin foil forming undulations capable of being deformed depending on the respective pressure levels of the fresh air stream and the stale air stream. Methods for feeding polyunsaturated fatty acids to milk producing animals by top dressing a polyunsaturated fatty acid supplement on top of animal feed compositions and methods of making and using such compositions are also provided. The mixing bottle also includes a second enclosed region for holding one of the two tubes that provides an air-tight coupling between the output leg of the handpiece and a collecting bottle. When the physical address does not match any of the block addresses in the table, the irreversibly writeable memory is referenced to read data stored at the physical address, and when the physical address matches one of the block addresses in the table, the irreversibly writeable memory is referenced to read data stored at the address of its associated substitute block portion.