Effect of in‐ovo Manganese Inoculation on Hatchability, Serum and Molecular Levels of Antioxidants, Bone Development, and Meat Quality of Broiler Chicks

ABSTRACT This study aimed to investigate the influence of in‐ovo injection of manganese (Mn) on hatchability, hatching weight, bone development and mineralisation, meat quality of breast and thigh, and also the serum and molecular levels of some antioxidants in the post‐hatched chicks. About 350 fertile eggs were collected from a Hubbard efficiency plus breeder's flock of 42 weeks old, incubated at normal setting temperature (37.5°C) and relative humidity (RH 60%), and randomly allocated into three treatments. The eggs were labelled and randomly assembled into three groups with four replicates, and 25 eggs each. The treatment was designed as a control non‐inoculated group (CN), a vehicle‐inoculated group (CP, inoculated with 0.1 mL physiological saline), and a Mn‐inoculated group (0.01 mg/egg, dissolved in 0.1 mL physiological saline). The site of injection was the air cell at the broad end of the eggs on the 12th day of incubation. On the day of the hatch, the rate and the hatchling's weight were recorded. The serum‐reduced glutathione (GSH) concentrations and superoxide dismutase activity (SOD) were assessed in 7‐day‐old chicks. On the molecular level, qRT‐PCR for nuclear factor erythroid 2‐related factor 2 (Nrf2) and superoxide dismutase (SOD) genes was performed in the breast skeletal muscles at post‐hatch day 7. Femur proximal metaphysis histo‐morphometric analysis was done with computerised morphometric measurements. The thigh and breast meat quality were evaluated. In‐ovo inoculation of organic manganese (Mn) showed no significant adverse effects on hatchability ( p = 0.51), hatchling weight ( p = 0.93), or mortality during the rearing period ( p = 0.67). Conversely, Mn supplementation significantly enhanced bone mineralisation and upregulated the expression of antioxidant‐related genes, including SOD ( p = 0.027) and Nrf2 ( p = 0.018), in muscle tissue. Furthermore, in‐ovo Mn administration contributed to improved meat quality by significantly reducing fat content ( p < 0.01) and pH ( p < 0.0001), while increasing ash content ( p < 0.0001), potentially extending the shelf life of broiler meat.