الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Poultry farming has long been a vital agricultural industry in Egypt. Its enhancement is one of the primary goals of both the corporate and public sectors. The broiler was prolific, grew quickly, had a small body size, and produced a lot of meat. As a result, commercial broiler production has received a lot of attention in recent years. The poultry production industry has shown substantial progress in recent years. This tremendous advancement was accompanied by a large rise in output rates, whether for meat or eggs. Unfortunately, this development has unfavourable consequences, including a decrease in immuneresponse and antioxidant status. As a result, several synthetic feed additives, such as pharmaceuticals and antibiotics (antimicrobial agents), were utilized as growth promoters in chicken diets to enhance productivity, adjust gut microbiota, manage diseases, and enhance immune response (Bedford, 2000; Whitehead, 2002). Different approaches have been implemented to increase the return on poultry investment for the sustainability of the poultry sector and its primary role in providing high-quality animal protein, and dietary modulation represents a noticeable way of altering animal performance (Abou El-Ghar and Abd El-Karim, 2016; Fathi et al., 2016; Akbari et al., 2016, 2018; El-Senousey et al., 2018). In terms of nutrition, delivering a well-balanced diet that meets all nutritional requirements is the foundation of a successful production (Uniyal et al., 2017; Sebola and Mlambo, 2018). Feed additives may be used to mitigate the effects of various nutritional abnormalities. Recent technologies, such as the utilization of nanoparticles, are being widely employed to improve chicken production in terms of quantity and quality (El-Rayes et al., 2019). In terms of multifunctional physical and chemical characteristics, as well as ease of synthesis, selenium nanoparticles (Se-NPs) had the second rank after nano-zinc among the metal nanoparticles (NPs) produced globally each year (Bai et al., 2020). In 2003, mammalian proteomes were characterized and 25selenoproteins were identified (Kryukov et al., 2003). Later, 26 genes encoding different selenoproteins were identified (Lei, 2017; Zhao et al., 2017). There were different sources of selenium can used in poultry nutrition, organic selenium sources found their way into animal/poultry nutrition, and a new effective source of organic Se (OH-SeMet) combining major advantages of Se-yeast and pure SeMet was successfully tested and found its way to poultry/animal industry (Briens et al., 2013, 2014; Jlali et al., 2013). The physical form of selenium influences its bioavailability (Zhang et al., 2008). Nano-selenium (nano-Se) has received a lot of interest recently since the nanoscale particles have unique properties such as high surface activity, high catalytic efficiency, large surface area, strong adsorption capacity, and low toxicity (Samak et al., 2018 and Shahnawaz et al., 2018). An experiment was conducted to evaluate toxicological effects of different selenium sources and levels on broiler by Selim et al. (2015). The histological examination of liver showed some sever pathological changes due to increasing Se level from 0.15 to 0.30 ppm. While using 0.15 ppm of inorganic or organic forms of Se showed normal histological structure of liver tissues. 0.3 ppm NaSe showed pathological changes as focal large area of necrosis replaced and displaced with large area of inflammatory cells mainly macrophage and inflammatory cells. Furthermore, Saad et al., (2013) observed that no gross inflammatory lesions were observed in the cecum in birds necropsied at 21, and 25 days of age. They also noticed that the presence of lymphoid clusters was significantly higher in the liver of birds supplemented with organic selenium than the control group. Recently, Many investigations were conducted to evaluate the ability of replacing inorganic form (sodium selenite) by organic form (Se- yeast) of se in broiler performance The result observed that replacing inorganic selenium by organic selenium in the regular diet significantly increased the live weight of chickens (Mansoub et al., 2010, ChekaniAzar, et al. 2010). There were many studies conducted to evaluate the effects of different sources of selenium (organic and inorganic) on broilers but, restricted investigations were done to evaluate the effects of different forms of Nano-se. Consequently, the aim of this study was to investigate the effect of Nano Selenium forms on performance, physiological status and economic efficiency of broiler chickens.