Short communication: In ovo injection of all-trans retinoic acid causes adipocyte hypertrophy in embryos but lost its effect in posthatch chickens.

Abstract

The regulation of adipose deposition in broiler chickens is an important factor for production efficiency to poultry producers and health concerns to customers. Although vitamin A and its metabolite [all-trans retinoic acid (atRA)] have been used for studies on adipogenesis in mammals and avian, effects of embryonic atRA on adipose development in embryonic (E) and posthatch (D) ages in broiler chickens have not been studied yet. Different concentrations of atRA (0M-2μM) were injected in broiler eggs at E10, and adipose tissues were sampled at E16. Percentages of adipose tissues in chicken embryos were significantly increased in the group injected with 500nM of atRA compared to the 0M group (P<0.05). In addition, the adipocyte cross-sectional area (CSA) was significantly greater by in ovo injection of 500nM atRA compared to the injection of 0M (P<0.01). Moreover, in ovo atRA-injected embryos were hatched and BWs were measured at D0, D7, and D14. BWs were not different from those of the 0M group. Percentages of adipose tissues and CSA of the in ovo atRA-injected group (500nM) were not different from those of the 0M group at D14. Taken together, the current study clearly showed that in ovo injection of atRA promoted adipose deposition with hypertrophy during embryonic development, but its effects were not maintained in early posthatch age in broiler chickens, implying that embryonic atRA has an important role in the regulation of adipose development in chicken embryos.