Understanding the role of host genetics in regulating the bovine gut microbiome

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Beef is a highly nutritious component of the diet providing readily accessible protein and essential micronutrients in a relatively small serving. In many parts of the world significant parts of the population is undernourished, even in Canada. Beef cattle also make use of land resources that are unsuitable or inefficient for producing crops. Thus, in many nations, ruminant protein is an integral component of the human diet and its production has contributed to the development and elimination of poverty in human society. However, ruminants are seen as contributing significantly to global warming. This aspect can be mitigated by selecting for improved feed efficiency or conversion of forage to meat. Improving feed efficiency of cattle is one of the grand challenges for industry and society in order to meet increased human consumer's demand but also to lower production cost and to reduce the amount of greenhouse gas produced per kg of product as well as the manure waste. To date, the biological processes underlying cattle feed efficiency and methane production in the ruminants are still largely unknown. Past studies from my laboratory have revealed that the composition and activity of the rumen microbiota in cattle with high feed efficiency differs from those with low feed efficiency. Ruminants have evolved to possess a diverse population of microbes in their rumen that enable them to convert forage into nutrients for animal growth. This symbiotic microbiota can degrade most complex plant polysaccharides to produce short chain fatty acids, proteins, and vitamins, which provide satisfy the animal's energy requirement for maintenance and growth. This suggests that "rumen fermentation", as the starting point of nutrient digestion, is a major biological process determining individual feed efficiency. Although diet is a key factor for the rumen microbiome, recent research has highlighted that the microbiome can vary widely between animals fed the same diet in the same environment. Currently, we do not understand what impacts this aspect. This project seeks to increase our understanding of rumen function and how it is impacted by host genetics in order to improve its function and efficiency. We will ask the following questions: 1) Does the host genotype partially explain the variation in rumen microbial communities in feedlot cattle exhibiting differences in feed efficiency? 2). Can the microbiome of the lower gut of cattle also contribute to this variation and how? E.g. by impacting host gene expression and amino acid absorption and/or the host impacting microbial interactions and function in the lower gut? An understanding of this interaction can then form the basis of new approaches to manipulate it to help achieve more sustainable or environment friendly cattle production, the ultimate goal of my research program.