Influence of in ovo thermal manipulation on lipid metabolism in embryonic duck liver

The growth and development of poultry embryos are easily affected by environmental factors, such as the incubation temperature and humidity. Metabolism, including lipid metabolism, during the embryonic stage is also important for the growth and development of poultry. Our study aimed to investigate the effects of incubation temperature on embryonic lipid metabolism in the liver of ducks. To fully evaluate the effects, thermal treatment was given between embryonic ages 11 and 24 days with a 1 °C higher incubation temperature than the control group, and lipid metabolism parameters in the liver and blood serum were analyzed both at embryonic stage day 20 and 2 weeks post-hatching. Our results showed no significant changes in the embryonic stage in total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) in the blood serum (P>0.05). Additionally, the mRNA expression levels and enzyme activities of fatty acid synthase (FAS), acetyl CoA carboxylase (ACC), and elongase of very long chain fatty acids (ELOVL) did not show significant changes either in the embryonic stage or at hatching day 20 (P>0.05). However, there were significant changes in the gene expression and enzyme activities of TC, LDL-C and FAS at post-hatching stages (P≤0.05). These results may indicate that the thermal treatment has less influence on lipid metabolism in the embryonic stage but has a much stronger effect in the post-hatching stage.