22 The pre-ruminant microbiome: why do we care and where does it come from?

Abstract Abstract: Introduction Despite ruminant livestock being born with a non-functional rumen, the early rumen microbiome can have lasting impacts on animal performance. Identifying key sources of colonization of this early rumen microbiome are imperative to harnessing the programming potential of this microbial niche to improve long term health and performance. Objectives The objective of this collective work is to identify maternal influences on colonization of the neonatal gut microbiome. We hypothesize that environmental, genetic, and pathogenic disruptions during gestation and early lactation will have lasting impacts on the offspring, partially via impacts on the gut microbiome. Methods Research projects involving beef cattle and range sheep have been employed to characterize maternal influence on the neonatal gut microbiome. In all studies, microbial characterizations have been completed utilizing amplicon sequencing of the 16S rRNA and analysis via QIIME2. Alpha- and beta-diversity metrics in additional to differences in relative abundance of taxa have been evaluated. Results It is apparent across all studies that the neonate does in fact have a unique microbiome immediately after birth. Data also indicates that maternal factors impact offspring rumen microbiome including nutritional status of the dam during gestation and early lactation and mammary health. Furthermore, these studies have revealed several potential sources of colonization of the neonatal gut. Conclusion These data from several projects highlight opportunities for programming of the rumen microbiome to enhance long term health and performance.