Effect of in‐ovo inoculation of betaine on hatchability, serum antioxidant levels, muscle gene expression and intestinal development of broiler chicks

This study investigated the effects of in-ovo inoculation of betaine on hatchability, hatching weight, and intestinal development, as well as serum and expression levels of some antioxidants in the posthatched chicks. A total of 350 fertile eggs of Hubbard efficiency plus breeder's flock were incubated at normal incubation temperature (37.5°C) and randomly assembled into 3 groups with 4 replicates, and 25 eggs per each. The experimental groups were allocated as noninjected control group (CN), diluent-injected group (CP, 0.1 mL saline), and betaine-injected group (B, 2.5 mg in 0.1 mL saline). The injections were performed in the air cells of the eggs on the 12th day of the embryonic phase. Hatchability percentage, hatching weight, serum-reduced glutathione (GSH), and superoxide dismutase (SOD) were estimated in 7-day-old chicks. Moreover, expression levels of the nuclear factor erythroid 2-related factor 2 (Nrf2) and SOD were determined in the breast skeletal muscles of chicks. Jejunum histo-morphometric analysis was assessed with computerised morphometric measurements. The results revealed that the hatchability percentage was not influenced by in-ovo injection of betaine or vehicle while betaine significantly increased the hatchling's weight of chicks. Moreover, there were a significant increase in SOD and Nrf2 mRNA expression levels. In-ovo injection of betaine significantly induced positive effects on intestinal morphometry by ameliorating the jejunal villus length, the ratio of villus height to villus width, and absorptive surface area.