Abnormal histopathology, fat percent and hepatic apolipoprotein A I and apolipoprotein B100 mRNA expression in fatty liver hemorrhagic syndrome and their improvement by soybean lecithin

To investigate the etiopathogenesis of fatty liver hemorrhagic syndrome (FLHS) and the protective effects of soybean lecithin against FLHS in laying hens, 135 healthy 300-day-old Hyline laying hens were randomly divided into groups: control (group 1), diseased (group 2), and protected (group 3). Each group contained 45 layers with 3 replicates. The birds in these 3 groups were fed a control diet, a high-energy/low-protein (HELP) diet or the HELP diet supplemented with 3% soybean lecithin instead of maize. The fat percent in the liver was calculated. Histopathological changes in the liver were determined by staining, and the mRNA expression levels of apolipoproteinA I (apoA I) and apolipoprotein B₁₀₀ (apoB₁₀₀) in the liver were determined by RT-PCR. The results showed that the fat percent in the liver of group 2 was much higher (P < 0.01) than that of group 1 and group 2 on d 30 and 60. The histology of the liver in group 2 on d 30 and 60 displayed various degrees of liver lesions, while the hepatocytes showed a normal structure in group 3 with mild microvesicular steatosis in the liver cell on d 30 and 60. The mRNA expression levels of apoA I and apoB₁₀₀ in the livers were variable throughout the experiment. The expression level of apoA I in group 2 significantly decreased on d 60 (P < 0.05); the expression level of apoB₁₀₀ slightly increased on d 30 in group 2, while it sharply decreased on d 60. Compared to group 1, the expression level of apoB₁₀₀ showed no significant difference in group 3 (P < 0.05). This study indicated that FLHS induced pathological changes and abnormal expression of apoA I and apoB₁₀₀ in the livers of laying hens and that soybean lecithin alleviated these abnormal changes.