عنوان مقاله [English]
Introduction Prebiotics are non-digestible additives that stimulate the growth or activity of one or more bacteria in the gut, which can have a beneficial effect on the host and thus improve the health of the host animal. Prebiotics increase feed intake, final weight and improve feed conversion when fed to broilers. Prebiotics cause changes in the blood parameters and immune response in broilers. Numerous studies have shown the antibacterial properties of silver nano-particles and their useful applications in the poultry industry. These include increasing feed intake and decreasing the number of pathogen microbes in the gastrointestinal tract that cause bacterial cell death by binding nano-silver to the surface of gram-negative bacterial membranes through sulfur-containing proteins and by altering the membrane permeability and respiratory chain. Inflammation is the result of induction of oxygen-free radicals by silver nanoparticles, which leads to impaired digestion and absorption of nutrients in the bird's gastrointestinal tract. Many studies have shown the importance of natural flora in maintaining bird health and found that the flora in these sites had a profound effect on the process of making prebiotic consumables in poultry. Adding prebiotic compounds, especially fructans to broilers, improves weight gain and feed conversion ratio and carcass weight due to increased length and density villi distribution. The aim of this experiment was to investigate the effect of combined prebiotics and nano-silver on growth performance, blood indices, immune response and microbial population of ceca in broiler.
Materials and Methods In this experiment, 432 one-day-old male Ross 308 broiler chicks were used in a 3 × 3 factorial arrangement with completely randomized design with 9 treatments, 4 replications and 12 observations per replicate. The composition of the experimental diets was determined using the Ross 308 strain rearing guide. The basal diets were identical in energy and other nutrients. In this experiment silver nanoparticles were added 0, 400, 800 ml in drinking water and prebiotic added 0.025 and 0.5 % to the basal diets. The mean body weight gain, feed intake, feed conversion ratio were determined at the 1 to 42 days. Blood samples were taken from all experimental units for 10, 24 and 42 days to measure the titers of Newcastle, Infectious Bursal, and influenza antibodies. The blood sample was slowly poured into sterile lid tubes and transferred to the laboratory in an ice tank. In the laboratory, blood samples were centrifuged at 10,000 RPM for 10 minutes, followed by Newcastle antibody titers (Hemagglutination inhibition) and Infectious Bursal antibody titers by ELISA (Enzyme-Linked Immunosorbent Assay). The infectious influenza antibody titers were determined by ELISA .At the end of the experiment, after slaughter and carcass analysis, Cecal contents were extracted with a syringe (3 ml). And they were transferred to the lab to count the number of bacteria. Mac County medium was used for counting Coli bacillus, MRS agar for lactobacillus count. Salmonella was cultured on BGA (Brilliant Green Agar) specified media (Merck, Germany) at 37°C for 24 hrs. Data analysis was performed using SAS software and mean comparison with Duncan test at 5% level.
Results and Discussion There was a statistically significant difference in feed intake, weight gain and feed conversion ratio using silver nano-particles and prebiotics different levels between in total period of experiment (P<0.05). There was a statistically significant difference in the level of serum HDL, LDL, and TP in different levels of prebiotic (P<0.05). The lowest total number of bacilli and Salmonella was observed in 0.5% prebiotic treatment. The highest number of lactobacilli was observed in the treatments containing 0.25% and 0.5% prebiotics. The highest number of Coli bacilli and Salmonella was observed in the treatment without silver nanoparticles and the lowest in the treatment containing 800 ml. Also, the highest number of lactobacilli in treatment was 800 ml (P<0.05).The results of this study showed that using 0.5% prebiotic level in the diet of broiler chickens improved the growth performance and immune system. Also, the use of 800 ml levels reduced the number of harmful bacteria in the ceca of broiler chickens
Conclusion According to the results of this experiment, the use of prebiotics and silver nano-particles in the diet and water can improve the performance of the chicks during rearing period. 0.5% of prebiotics in broiler diets and 800 ml of silver nanoparticles decreased the number of harmful bacteria and increased the beneficial bacteria in broiler ceca.