Response of Anti-Oxidative Stress Genes in Liver and Intestine in Broilers Fed Organic Acid and Silver Nanoparticles Coated on Zeolite in Starter Period

Abstract

Extended Abstract Background: The use of food supplements to improve growth, optimal production and increase feed efficiency in feeding livestock and poultry has become a common thing as a suitable solution in using feed as well as possible. Along with the progress of the nano industry, attention has been paid to nanoparticles, especially silver nanoparticles, as an antibacterial agent and growth promoter. Silver nanoparticles can be considered as growth stimulating antibiotics and affect the growth and health of livestock and poultry. The mechanism of the effect of silver on pathogenic cells can be due to the high absorption capacity of silver ions, which immediately enters the bacterial cell membrane and makes the cell membrane leaky. On the other hand, organic acids and their salts have found a special place as an additive in livestock and poultry nutrition, and by having growth stimulating effects, they are known as a suitable alternative to antibiotics. The use of organic acids supplement improved the performance of broiler chickens by improving feed consumption, digestion and absorption, reducing the production of toxic substances and increasing favorable intestinal microorganisms, reducing the occurrence of infections and modulating the immune response of poultry. Also, zeolite is a mineral material of hydrated aluminosilicates, which has a three-dimensional and highly porous crystalline structure and contains alkaline elements such as potassium, sodium, calcium, and magnesium. Recently, it has been proposed that silver nanoparticles can act as one of the factors inducing oxidative stress and affect the expression of oxidative genes. This research was conducted with the aim of investigating the effect of silver nanoparticles coated on zeolite and organic acid on the relative expression of superoxide dismutase, glutathione peroxidase and catalase genes in the liver of broiler chickens. Methods: This experiment was conducted using 450 broiler chickens in five treatments and six replications and 15 broiler chickens in each experimental unit in a completely randomized design at the Poultry Research Station of Gorgan University of Agricultural Sciences and Natural Resources. Their nutritional requirements for the starter periods (1-21 days) were prepared according to the recommendation of the Cobb 500 strain maintenance guide and the food rations were adjusted using the UFFDA software. Experimental treatments include: 1) control treatment, 2) control treatment supplemented with 1% zeolite, 3) control treatment supplemented with 1% zeolite coated with 0.5% nanosilver, 4) control treatment supplemented with 0.15% The percentage of organic acid and 5) control treatment supplemented with 1% zeolite covered in 0.5% nanosilver and 0.15% organic acid. The composition and properties of silver nanoparticles were determined by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD). To perform molecular tests, total RNA was first extracted using TRIzol extraction kit (Sigma Aldrich) and 1% agarose gel was used to determine the quality of RNA extracted from tissues. On the 21st day of breeding period, randomly from 3 biological replicates and 3 technical replicates, a piece of 1 cm long was separated from the liver and small intestine tissue and after transferring to a microtube, to check the relative expression of  superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) genes were transferred to liquid nitrogen. Results: The data of this research showed that the relative expression of SOD gene in all experimental groups was lower than the control group on the 21st day of the breeding period in liver tissue, so that the lowest relative expression of SOD gene was related to Z group (p<0.05). The relative expression of GPX gene was significantly increased in the Z, NS and NSOA groups compared to the control group; While in OA group, the relative expression of GPX gene was significantly lower than the control group (p<0.05). In OA, NS and Z groups, the relative expression of CAT gene was significantly lower than the control group (p<0.05). Also, in the intestinal tissue, the results of our experiment showed that on the 21st day of the breeding period, the experimental groups decreased the relative expression of the SOD gene, so that the lowest relative expression was related to the NS group (p<0.05). The relative expression of the GPX gene in the intestinal tissue was significantly lower in the experimental groups than in the control group (p<0.05). Evaluation of the relative expression of CAT gene in intestinal tissue in NSOA, NS and OA groups were significantly lower than the control group (p<0.05); NS and OA groups had the lowest relative expression. Conclusions: The treatments containing silver nanoparticles and zeolite showed the greatest effect in the relative expression of SOD, GPX and CAT genes, while the organic acid treatment decreased the relative expression of the mentioned genes. Since the intestine is the first site of absorption of digested food, the cells of the intestinal tissue, as the first defense barrier against free radicals, may show a better response to the liver by increasing the expression of oxidative genes against oxidative food compounds or more genes be involved in the antioxidant system. In the present experiment, changes and a decrease in the relative expression of all three SOD, GPX and CAT genes were observed in the intestinal tissue