Embryonic nano lauric acid delivery modulates lipid metabolism, oxidative balance, and gut morphogenesis in broiler chicks

The in ovo-injection technique was employed as an early-life nutritional strategy to improve the health and productivity of birds by delivering nutrients and bioactive compounds directly to the developing embryo. This study explored the innovative use of in ovo administration of nano-lauric acid (NLA) as a strategy for the metabolic programming of broiler chicks. The goal was to improve hatchability, stimulate hepatic antioxidant activity, regulate growth-related genes, and support intestinal development in newly hatched chicks. A total of 400 fertile eggs from a 40-week-old Arbor Acres breeder flock were randomly divided into four treatment groups: a non-injected control group (CN), a vehicle-injected control group (CP; 0.1 mL of sterile distilled water), and two NLA-treated groups receiving either 2.5 mg/egg (NLA 2.5) or 5 mg/egg (NLA 5) of NLA, each dissolved in 0.1 mL of sterile distilled water. Injections were administered into the yolk sac on day 12 of incubation. Post-hatching, the hatchability percentage was recorded. Serum lipid profiles, hepatic redox status, and the expression level of hepatic genes, nuclear factor erythroid 2-related factor 2 (NRF2), mitochondrial superoxide dismutase 2 (mt-SOD2), and insulin-like growth factors 1 and 2 (IGF-1 and IGF-2) were evaluated. Additionally, the intestinal morphology of the newly hatched chicks was examined. Hatchability % was significantly reduced in the NLA 5 group (80%) compared to the CN (98%), CP (97%), and NLA 2.5 (96%) groups. The findings showed that in ovo injection of NLA at 2.5 mg/egg was therefore identified as optimal, significantly improving lipid metabolism by reducing serum triglycerides, LDL, VLDL, and cholesterol, while increasing HDL cholesterol compared to controls (P < 0.05). Hepatic antioxidant defense was significantly improved through the decrease of malondialdehyde (MDA) and increase of reduced glutathione (GSH) concentrations (P < 0.05). This enhancement was associated with the upregulation of NRF-2 and mt-SOD2 by (4.04; 3.69-folds, respectively) and stimulation of anabolic signaling genes IGF-1 and IGF-2 by (4.08 and 2.3-folds; respectively) (P < 0.05). In addition, intestinal development has been significantly promoted via increased villus height and crypt depth (P < 0.05). Our findings demonstrate that in ovo NLA supplementation at 2.5 mg/egg effectively enhances lipid utilization, activates NRF2-mediated antioxidant pathways, and stimulates anabolic signaling. This targeted nutritional strategy proves to be a safe and effective method for pre-hatch metabolic programming, with significant potential to improve post-hatch health and performance in broilers.