Neutral alpha amino diacid complexes of trace minerals and their use for animal nutrition. Such subpopulations will have differential responses to therapies, and thus treatments can be tailored to particular patients. The flexible substrate is then folded so as to stack at least some of the microelectronic elements in substantially vertical alignment with one another to provide a stacked assembly with the conductive terminals exposed at the bottom end of the stack and the test contacts exposed at the top end of the stack.