The omics side of fatty liver: A holistic approach for a commonly occurring peripartal disease

Compared with other stages of the lactation cycle, the transition period (from 3 weeks before to 3 weeks after calving) is critically important to health, production, and profitability of dairy cows. Due to the multifaceted physiological adaptations to lactation, dairy cows are at serious risk of developing metabolic disorders in the immediate weeks postpartum. Fatty liver (i.e., hepatic lipidosis) is a major metabolic disorder afflicting dairy cows in early lactation and is associated with decreased health status and reproductive performance. Fatty liver develops when the hepatic uptake of fatty acids exceeds the capacity of the organ to oxidize and/or export them as very-low density lipoproteins them. These events are often preceded by high concentrations of fatty acids in plasma mobilized from adipose tissue. Excess triacylglycerol accumulation in the liver can diminish physiologic functions of the liver. Studies of similar pathologies in humans and model organisms (e.g. mouse and rat) have revealed the complexity of the disease that goes beyond a simple disruption of lipid metabolic pathways. Advancements in computational biology, genome sequencing, and high-throughput technologies in the last decade have provided the tools to understand this metabolic disease using a systems rather than a reductionist approach. The application of “omics” technologies has enhanced understanding of the pathophysiology of fatty liver disease in peripartal dairy cows. This chapter focuses on the use of high-throughput technologies and bioinformatics to enhance our understanding of hepatic lipidosis, focusing on major breakthroughs generated using functional information from “omics” datasets. The goal is to provide specific examples of how these combined approaches have been used to advance our understanding of the pathophysiology of this commonly occurring metabolic disease.