Osteocalcin and Its Potential Functions for Preventing Fatty Liver Hemorrhagic Syndrome in Poultry

SIMPLE SUMMARY: Fatty liver hemorrhage syndrome is one of the main metabolic diseases in laying hens, which leads to lipid accumulation, fragile liver, rupture bleeding, and sudden death. Osteocalcin, a kind of noncollagenous protein, has recently been found to protect chickens from the disease. However, the most studies have focused on the use of osteocalcin in mammals. In this review, we try to outline the functions of osteocalcin in fatty liver hemorrhage syndrome in poultry based on the recent outcomes. ABSTRACT: Osteocalcin (OCN) is synthesized and secreted by differentiating osteoblasts. In addition to its role in bone, OCN acts as a hormone in the pancreas, liver, muscle, fat, and other organs to regulate multiple pathophysiological processes including glucose homeostasis and adipic acid metabolism. Fat metabolic disorder, such as excessive fat buildup, is related to non-alcoholic fatty liver disease (NAFLD) in humans. Similarly, fatty liver hemorrhage syndrome (FLHS) is a metabolic disease in laying hens, resulting from lipid accumulation in hepatocytes. FLHS affects hen health with significant impact on poultry egg production. Many studies have proposed that OCN has protective function in mammalian NAFLD, but its function in chicken FLHS and related mechanism have not been completely clarified. Recently, we have revealed that OCN prevents laying hens from FLHS through regulating the JNK pathway, and some pathways related to the disease progression have been identified through both in vivo and vitro investigations. In this view, we discussed the current findings for predicting the strategy for using OCN to prevent or reduce FLHS impact on poultry production.