Aug 22, 2017 · 1. INTRODUCTION. Animal digestion types are classified as herbivores (ruminants and hindgut fermenters), carnivores, and omnivores. Many ruminant microbiota profiling studies have focused on cattle because of their importance in the beef and dairy industry (Brulc et al., 2009; Callaway et al., 2010; Jami & Mizrahi, 2012; Welkie, Stevenson, & Weimer, 2010).