Regulation of Gastrointestinal Growth and Function

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There are over 15 million ruminants in Canada producing milk and meat, which contributes over 40 billion dollars to Canada's economy. The ruminants raised on approximately 50,000 farms throughout Canada follow the highest standards of animal welfare, however gastrointestinal diseases and disorders in young and mature stock are still a serious threat to animal welfare and the profitability of agriculture. During the first week of life, ruminants are born as functional mongastrics, and the rumen remains non-functional until the introduction and consumption of feedstuffs such as grains and forages. The process of transition from their neonatal reliance on nutrients supplied from milk to nutrients supplied from grain and forages is of important economic and animal welfare significance to ruminant producers, as improvements to ruminant nutritional regimes in early life can decrease mortality and disease susceptibility, as well as increase weight gain and milk production. *** The overall hypothesis for this research is that gastrointestinal signaling pathways that stimulate functional adaptations in the ruminant are regulated by specific interactions among diet and microbiota. The longterm goal of this research is to improve our understanding of gastrointestinal growth and function and to develop novel and effective strategies to enhance ruminant gastrointestinal health. The aim of the first experiment is to determine how weaning can impact gastrointestinal growth of the young ruminant via IGF-1 signaling pathways. The second experiment examines the impact of microbiota inoculation from mature ruminants on the gastrointestinal development via IGF-1 signaling in immature ruminants. The final experiment will determine how GLP-2 and IGF-1 signaling pathways in the intestine communicate with the rumen to impact its growth and function.**** This research will provide a comprehensive understanding of the integrated responses of the gastrointestinal tract to the sensory information it receives from the diet, microbiota and their metabolite end-products. The proposed research will also provide insight into how dietary and microbial factors can impact gastrointestinal growth and function across many species. The resulting knowledge and innovations related to improving gastrointestinal health in livestock using nutrients and microbiota will ultimately aid in the design of antibiotic-free animal production systems.***