Histopathologic investigation of liver and kidney tissues in broiler chickens fed silver nanoparticles coated on zeolite

Nanotechnology can be very effective in increasing productivity through food, nutrition, hygiene and breeding of livestock, poultry and aquatic animals. Nanotechnology has received a great attention within scientific and industrial communities in many countries including Iran. Nanotechnology, as a powerful new technology has the ability of creating massive revolution in feed supply and agricultural systems at global scale by improving diet quality and consequently health and growth performance (Buzea et al. 2007). One of the reasons for the extensive use of these particles in poultry units is due to their antimicrobial properties. Nanotechnology deals with structures that their dimensions are approximately between 1 to 100 nanometers (Sriram et al. 2010). Silver nanoparticles are among widely used nanoparticles. The interest in the use of silver based antimicrobial agents was primarily due to the emergence of antibiotic resistance among microbial populations and due to the fact that resistance to silver is not commonly encountered (Prestinaci et al. 2015). Nanoparticles according to their size, have new properties in comparison with mass materials. Silver nanoparticles in many characters are more effective compared with other metals. In addition, beneficial effects of silver nanoparticles are due to the size and resemblance of nanoparticles which caused their passage through the biological membrane and through the cell (Wang et al. 2015). Silver nanoparticles because of their small size for proper homogeneity can be coated by zeolite particles. Zeolite has been used in broiler feed due to its resistant chemical structure and it’s not digested and catalyzed by passing through the digestive tract. Also, zeolites are crystalline, hydrated aluminosilicates of alkali and alkaline earth cations. Among many properties attributed to zeolites, two of the most characteristics that relates to their effectiveness in animal nutrition are their ability to lose and gain water reversibly and being capable of exchanging selectively a variety of cations in their structure without much changes of structure (Wawrzyniak et al. 2017). Therefore, zeolite can be considered as an appropriate carrier for nanoparticles. Based on these facts, silver nanoparticles had been replaced instead of massive particles of silver and been more effective in different industry. Silver nanoparticles lead to the production of reactive oxygen species and oxidative stress in cells (Ahmadi and Kurdestani. 2010). Liver as the biggest gland in the body has several roles. In addition to digestive and metabolic activities, liver has immunological and detoxification activity (Maser et al. 1994). Silver nanoparticles can inter the cells and communicate with intracellular structures (Panzarini et al. 2018). The ability of silver nanoparticles to infiltrate into tissues led to resistance against their removal in blood and then, cause particles aggregation in utilizable tissues. Due to the reports of the aggregating and dangerous effects of silver nanoparticles, it seems necessary to histopathologically investigate liver and kidney of broiler chicken fed silver nanoparticles.

This experiment was performed at the Poultry Research Station Faculty of Animal Science at the Gorgan University of Agricultural and Natural Resources. This experiment was designed to evaluate the effect of silver nanoparticles coated on zeolite and organic acid on liver and kidney histology in broiler chickens. A total of 375 one-day old broiler chicks (Cobb 500) was randomly assigned into five treatment groups containing of five replicates with 15 birds in each replicate. Five dietary treatments groups were, (1) basal diet (control), (2) basal diet containing 1% zeolite, (3) basal diet containing 1% of zeolite-coated with 0.5% silver nanoparticles, (4) basal diet containing 0.15% organic acids and (5) basal diet containing 1% of zeolite-coated with 0.5% of silver nanoparticles and 0.15% a mixture of organic acid. The basal diet prepared for starter and growth periods, and composition of the experimental diets prepared according to the requirements prescribed for Cobb 500 (Cobb. 2012). Birds has ad libitum access to feed and water for all treatment groups and continuous lighting program was provided during the experiment. Two chickens per each replicate were slaughtered on day 42 for evaluating the histology of liver and kidney. The tissue samples were fixed in a 10% buffered formalin, processed through graded alcohols and xylene and embedded in paraffin blocks. Tissue sections were cut for 5 m at multiple levels and routinely stained with haematoxylin-eosin (H&E). Mounted slides were examined and photographed under a light microscope. Hepatocytes and kidney cells were evaluated for histopathologic lesions, focal point of lymph nodes in the liver parenchyma, around the portal region and focal point of heterophobia. Data were analyzed based on a completely randomized design using general linear method (GLM) procedure by using SAS (2003) software. Mean comparison was done by Duncan's multiple range tests at 5% level with values of P<0.05 being considered significantly different.

The experimental results didn’t show any significant difference between experimental treatments on liver and kidney histopathology in broiler chickens (P>0.05). Liver in the body as a detoxifying organ absorbs a significant part of toxins produced from harmful microbes and external particles into the blood. However, it was not possible to remove them completely in the tissues because of high ability of nanoparticles in dispersion in tissues of broiler chickens (Zargaran-Esfahani et al. 2010). Increased liver weight in the presence of nanoparticles due to inflammation in these organs has been reported in some studies. The results of this experiment didn’t show any significant difference between treatments on liver and kidney histopathology in broiler chickens and there were no toxicological effects of silver nanoparticles on liver and kidney tissues (P>0.05).

Nanoparticles coated on zeolite and with organic acid can be used as an additive supplement without any adverse effect on feeding and histopathological liver and kidney in broiler chickens.