Through the years, several authors have proposed classifications of livestock systems (Boyazoglu and flamant,1990; Sere' and steinfeld, 1996; Nardone,1996;Sorensen et al;2006 and many others). Recently, Steinfeld et al. (2006) indicated 11 livestock systems and devendra (2007) gave a comprehensive classification of integrated livestock systems in the Oceania area. Taking these into account, we will focus on three main categories of systems.