The post genomic era will result in many new molecular tools for evaluating the factors influencing fertility and reproductive performance in domestic livestock and poultry. There is currently considerable interest and practical merit in examining the regulatory steps involved in the process of gene transcription. Currently, oligo-based and cDNA microarray techniques make it possible to understand many of the factors controlling the regulation of gene transcription and globally evaluate gene expression profiles by looking at the relative abundance of gene-specific mRNA in tissues. These techniques provide an unprecedented amount of information and are only now being used to examine key reproductive, developmental, and performance characteristics in cattle. They also promise to provide a tremendous amount of new information that can be used to understand and diagnose key issues that limit reproductive performance. The science of nutrigenomics has begun to use information obtained from basic studies of the genome to evaluate the effects of diet and nutrient management schemes on gene expression. Preliminary studies have shown the value of such techniques and suggest that it will be possible to use specific gene expression patterns to evaluate the effects of nutrition on key metabolic processes relating to reproductive performance. While the effects of nutrition on fertility are only partially understood, modern nutrigenomics will undoubtedly play a key role in developing strategies for addressing some of the limitations in reproductive performance.