The goal is to add economic value by introducing specific substances or tissue modifications. This could produce unintended environmental effects relating to the place of introduction or the nature of expression of GMOs. Despite these prevalent environmental implications, however, livestock contributes to the livelihoods of millions of the world’s poor, providing an income source, and sometimes the only source, for many. Therefore, measuring livestock impacts and driving efficiency in the production line is vital. Environmentally relevant statistics on livestock include the number and characteristics of live animals, as well as antibiotics and hormones used for them.