RNA-seq Reveals Differential Gene Expression in the Liver between Broiler Chickens with High and Low Feed Efficiencies

With feed costs representing over two-thirds of the total cost of poultry production, optimizing feed efficiency while simultaneously decreasing nitrogenous waste is vital for sustainable development of poultry production. Residual feed intake (RFI)—the expected intake of an animal subtracted from its observed intake—is a measure of feed efficiency uninfluenced by production traits such as weight gain. It has a low to moderate heritability, suggesting that overall feed efficiency of a flock can be improved not only by environmental factors such as diet formulation, but through genetic selection of specific genes and metabolic pathways that affect RFI. However, these genes and metabolic pathways are not well understood. Liver tissue has expansive digestive and metabolic functions that can play a role in feed efficiency and energy uptake. Our aim is to find the genes and metabolic pathways responsible for feed efficiency through analyzing differential gene expression in liver tissue of broiler chickens showing differential feed efficiencies. We used RNA-seq to quantify genome-wide gene expression levels in the liver tissue samples that were harvested from 24 broiler chickens raised in two different seasons. Twelve birds, six with high feed efficiencies and six with low feed efficiencies, were sampled in the spring. Likewise, the other 12 birds were sampled in the summer. Our preliminary results indicate that there is differential gene expression between the broiler chickens with high and low feed efficiencies. Further analyses are underway to determine which pathways are differentially regulated between these two groups of chickens.