It is well known that selenium supplementation improves the efficiency of glutathione mediated antioxidant system by increasing the level of selenium dependent glutathione peroxidase enzyme and this led to increase the concentration of tissue reduced glutathione GSH and this led to decrease lipid peroxidation in chick tissues which is known to have high levels of polyunsaturated fatty acids
Hi Dr. Abdullah Fathi Abdul-Majeed, kindly refer below-mentioned literature which clearly shows the beneficial role of in-ovo injection with selenium on improving immunity and higher chick's weight at hatch. However, the cost-benefit ratio must be critically evaluated before recommending to the poultry industry.
Hassan, A. M. (2018). Effect of in ovo injection with nano-selenium or nano-zinc on post-hatch growth performance and physiological traits of broiler chicks. International Journal of Environment, Agriculture and Biotechnology, 3(2).
Lee, S. H., Lillehoj, H. S., Jang, S. I., Jeong, M. S., Xu, S. Z., Kim, J. B., ... & Bravo, D. M. (2014). Effects of in ovo injection with selenium on immune and antioxidant responses during experimental necrotic enteritis in broiler chickens. Poultry Science, 93(5), 1113-1121.