364. Butyrate Glycerides Ameliorate High-Energy and Low-Protein Diet Induced Fatty Liver Hemorrhagic Syndrome By Modulating Hepatic Lipid Metabolism and Mitochondrial Function in Laying Hens.

Abstract Fatty liver hemorrhagic syndrome (FLHS) is a prevalent metabolic disorder in caged laying hens, especially during the later stages of their laying cycle, and causes substantial economic losses in the modern layer industry. Butyrate glycerides (BG), with monobutyrin as one of the major active components, possesses several properties, including antioxidant properties, and alleviates fatty liver damage caused by a high-fat diet. This study aimed to evaluate the protective effects of BG against high-energy, low-protein diet-induced FLHS in laying hens and to elucidate the mechanisms of BG regulates hepatic lipid metabolism and improves laying performance. A total of 384 50-week-old Hy-Line Brown laying hens were randomly assigned to four groups: CON (normal diet), HELP (high-energy, low-protein diet), LBG (HELP + 2 g/kg BG), and HBG (HELP + 4 g/kg BG), with six replicates of 16 birds per group for 8 weeks. The results showed that dietary BG supplementation improved laying performance in HELP diet-induced FLHS laying hens by increasing laying rate and decreasing feed conversion ratio (P < 0.05). BG also alleviated hepatic injury and lipid accumulation by reducing serum ALT, AST and hepatic TG content (P < 0.05), while upregulating hepatic fatty acid oxidation-related genes, including CPT1α and PPARα, and downregulating hepatic lipid synthesis-related genes, including PPARγ (P < 0.05). Moreover, BG enhanced hepatic antioxidant capacity, as evidenced by increased GSH-Px and CAT activities and decreased MDA content and ROS fluorescence intensity (P < 0.05). In parallel, BG improved liver mitochondrial dysfunction by improving mitochondrial ultrastructure, increasing autophagosome formation, and restoring Na⁺/K⁺-ATPase activities and expression of genes related to autophagy, including LC3, P62 and PINK1 (P < 0.05). Notably, liver metabolome profiling further showed that BG regulated glycerophospholipid metabolism by increasing L-acetylcarnitine (P < 0.05). Yolk lipidomics revealed that BG supplementation markedly reshaped HELP-induced alterations in yolk lipid species, mainly characterized by PE enrichment and TG reduction. Finally, vitro experiments in oleic acid-induced Leghorn male hepatocyte (LMH) cells further supported the role of monobutyrin in regulating lipid metabolism and autophagy. Collectively, these findings indicate that dietary BG alleviates HELP diet-induced FLHS in laying hens by regulating hepatic lipid metabolism, antioxidant capacity, and autophagy-related mitochondrial function, while monobutyrin (MB) may be an important active component contributing to these protective effects, supporting the potential use of BG as a feed additive to prevent lipid metabolism disorders in the laying hens.