Looking beyond the rumen: uncovering opportunities to improve health and performance by considering the whole gastrointestinal tract.

SUMMARYModulating the lower gastrointestinal tract (GIT) is an untapped opportunity for improvement in cattle production. The microbial communities across the GIT regions are closely related to host function and anatomical structures, impacting digestion and feed efficiency, the immune response, growth, and methane production. In this review, the characteristics of each GIT location are discussed to better understand how different anatomical structures of the host digestive tract and the microbial communities interact within and between GIT locations. There are several major issues faced by the cattle industry that are impacted by the lower GIT (duodenum, jejunum, ileum, cecum, and large intestines), including managing the inflammatory response, release of waste products, and food safety concerns. As there continues to be a push for agricultural sustainability, improved food safety, reduced economic losses, and efficient early life development, exploring the less understood contributions of the lower GIT is crucial. Finally, this review will explore increasingly convenient and affordable sampling and sequencing techniques that will transform our understanding of the bovine GIT.