This project is focussed on the health, productivity and welfare of sheep. We will concentrate on aspects of metabolism that affect lifelong health and wellbeing. Specifically, we will study a key aspect of metabolism referred to as one-carbon (1C) metabolism. This is important because it affects many key processes in the cell, including DNA synthesis, DNA methylation and cell proliferation. It does this by delivering methyl groups, which are central to these biochemical reactions. Deficiencies in metabolites involved in these pathways, such as choline, methionine, folate and vitamin B12, have adverse effects on animal development and wellbeing. For example, deficiencies in vitamin B12 and/or folate can affect fertility and fetal development, and lead to poor growth, vascular disease and metabolic syndrome in adult animals and humans. 1C metabolism pathways are complex and are affected by many genes. We hypothesise that mutations in these genes will affect 1C metabolism and the vulnerability of animals to micronutrient deficiencies. In this study we will identify such mutations, determine their functional significance (i.e. what they do and how important they are), test their impact in animals fed different diets, and find ways to use this information to improve the welfare of farm animals. Firstly, we will identify mutations (i.e. single nucleotide polymorphisms or SNPs) in around 40 genes directly affecting 1C metabolism, and in very closely related pathways involved in energy metabolism, cell proliferation, DNA synthesis and DNA methylation. To achieve this in sheep we will create our own sequence data. We estimate that we will identify 2000-4000 SNPs by these methods. We will then conduct a large-scale study with liver samples collected from around 300 sheep slaughtered at local abattoirs. We will genotype each sample (to determine which SNPs are present), measure gene expression and conduct a comprehensive analysis of all metabolites involved in 1C metabolism. Interpretation of these data will inform us on SNP function and how these SNPs affect pathways involved in 1C metabolism. To achieve this we will collate the required information and, using our knowledge of these genomes combined with complex bioinformatic analyses, determine the subset of SNPs that have the greatest impact on 1C metabolism. We expect to identify an estimated 100 or so functionally significant SNPs in these genes. We will then construct a 'SNP chip'; i.e. a tool to genotype sheep simultaneously and cheaply for many SNPs. This chip will be used to screen several flocks of sheep to identify 24 'Low-risk' and 24 'High-risk' weaned lambs, and 24 'Low-risk' and 24 'High-risk' breeding ewes. We will then monitor these animals in separate studies involving Control and Methyl-Deficient diets (i.e. two genotypes by two diets). For weaned lambs we will focus on effects on growth, animal health and liver metabolism, and carcass yields and composition. For breeding ewes we will also focus on animal health and liver metabolism, but extend studies to consider effects on chemical modifications to DNA (i.e. DNA methylation) in early (Day 16) male and female embryos. This research will provide novel insights into nutrient x gene interactions for many components of 1C metabolism and how they affect (a) lamb production efficiency, health and welfare, and (b) early development of mammalian embryos influencing fertility and the long-term health and wellbeing of offspring. We will be able to use this information to help breed animals with better functioning 1C metabolism (leading to permanent improvements in welfare and productivity) and/or to improve animal diets. As 1C metabolism also influences human development and health our results will also have biomedical research benefits, and increase the utility of sheep as a model species for this type of research.