The size and complexity of software systems make integration of the new/modified requirements to the software system costly and time consuming. The impact of requirements changes on other requirements, design elements and source code should be traced to determine parts of the software to be changed. Considerable research has been devoted to relating requirements and design artifacts with source...

The importance of essential trace minerals on livestock productivity has been realized for several decades. In improved agricultural systems, the supplementation of essential trace minerals has lead to increased livestock production as measured by body weight gain and reproductive performance. Recently, the importance of trace mineral nutrition on immune competence in livestock has gained atten...

The study of trace element metabolism has intensified in the last 20 years due mainly to the availability of highly purified diets and to the development of sophisticated instrumentation capable of detecting minute amounts of elements in tissues and feeds. Since 1957, Se, Cr, Sn, V, F, Si and Ni have been isolated as essential nutrients for animal metabolism (Schwartz 1974). The recommended req...