Application of nutrigenomics in small ruminants: Lactation, growth, and beyond

Ruminants have a very special niche in the animal kingdom, and are the most important livestock species providing milk, meat, and wool for humans from consumption of highly-fibrous feedstuffs. Cattle, goat and sheep have been widely-used for years as models to study ruminal fermentation and the mechanisms whereby tissues utilize nutrients for milk synthesis, growth, wool accretion, and reproduction. The advent of high-throughput technologies to study an animal's genome, proteome, and metabolome (i.e., “omics” tools) offered ruminant scientists the opportunity to study multiple levels of biological information to better understand the whole animal response to nutrition, environment, physiological state, and their interactions. The omics revolution gave rise to the field of nutrigenomics, i.e. the study of the genome-wide influences of nutrition through alteration in mRNA, protein, and metabolite expression or abundance. This field of research is relatively new in ruminants, and particularly sheep and goats. Dietary compounds affect gene expression directly or indirectly via interactions with transcription factors including ligand-dependent nuclear receptors. New knowledge generated through the application of functional analyses of transcriptomic, proteomic, and metabolomic data sets in goat and sheep is discussed.