The total ban on antibiotics as growth promoters in livestock nutrition, introduced in EU (European Union) countries on 1 January 2006, presented animal nutritionists with a considerable challenge in finding alternatives. First, the additives had to protect animals’ digestive tracts from pathogenic bacteria, and second, they should be inert in relation to the animals’ bodies. After many experiments, phytobiotics seem like they may be an effective alternative. This article aims to review key scientific articles relating to the use of phytobiotics of various origins in the feeding of chickens for fattening. The review of the available literature brings together the most important research findings on the effects of phytobiotic supplementation on growth performance, gut microbiota, antioxidant status and immune system of broiler chickens. Phytobiotics are natural plant substances produced to protect plants against pathogenic microorganisms. Phytobiotics are classified as a group of biologically active compounds with a broad chemical diversity and may include terpenes, triterpenes and flavonoids. Based on the collected information, it can be concluded that the use of phytobiotics in appropriate quantities and proportions in feed for broiler chickens influences the proper functioning of the digestive tract by, among other things, stimulating beneficial microbiota and secretion of digestive enzymes. In addition, the introduction of such feed additives has an impact on the alleviation of inflammation, supports the functioning of the immune system and has a positive influence on production results.

The modern broiler chicken industry is connected with various disorders of the skeletal system. The fast-growing birds by increased weight gain often have leg problem which leads to economic losses. The correct bone development of broilers is highly correlated with calcium and phosphorus ratio (about 2:1) so providing these macroelements with diet seemed to be fundamental. The most common inorganic sources such as limestone, mono- and di-calcium phosphates are commonly used nowadays. The doses in feed generally are in the range of 6–6.5 g/kg for Ca and 2–3.5 g/kg for P, depending on the supplementation of phytase. However, the bioavailability of inorganic sources is poorer than organic sources. This fact is important in reference to their impact on the environment. Because of the continuous search for alternative sources of calcium or phosphorus, with better bioavailability due to, for example, their size, the scientific area of nanotechnology arouses increasing interest. It is well-known nanoparticles have a great potential even at very low doses. Some research focused on calcium-phosphorus compounds already demonstrated no negative effect on birds’ health, improvement in production results and bone quality, opportunity to use lower dosages of nano sources and decreasing content of Ca and P in excreta (by ca. 50%). Thus, this aspect may be the new trend during the next years. However, the further studies should be performed.

There are numerous applications of graphene in biomedicine and they can be classified into several main areas: delivery systems, sensors, tissue engineering and biological agents. The growing biomedical field of applications of graphene and its derivates raises questions regarding their toxicity. We will demonstrate an analysis of the toxicity of two forms of graphene using four various biological models: zebrafish (Danio rerio) embryo, duckweed (Lemna minor), human HS-5 cells and bacteria (Staphylococcus aureus). The toxicity of pristine graphene (PG) and graphene oxide (GO) was tested at concentrations of 5, 10, 20, 50 and 100 µg/mL. Higher toxicity was noted after administration of high doses of PG and GO in all tested biological models. Hydrophilic GO shows greater toxicity to biological models living in the entire volume of the culture medium (zebrafish, duckweed, S. aureus). PG showed the highest toxicity to adherent cells growing on the bottom of the culture plates—human HS-5 cells. The differences in toxicity between the tested graphene materials result from their physicochemical properties and the model used. Dose-dependent toxicity has been demonstrated with both forms of graphene.

Silver nanoparticles (AgNPs) are found in open waters, but the effect of their low concentrations on an organism’s homeostasis is not fully understood. The aim of the study was to determine the short-term exposure effects of AgNPs coated by PvP (polyvinylpyrrolidone) on the homeostasis of livers and gonads in zebrafish. Sexually mature zebrafish were exposed for seven days to silver ions (0.01 mg/dm³) or AgNPs (0.01; 0.05; 0.1; 0.5; 1.0 mg/dm³). On the last day, the liver, testes, and ovaries were subjected to a histology analysis. In the liver, we analyzed the expression of the cat, gpx1a, gsr, sod1, and cyp1a genes. On the last day of the experiment, the lowest survival rate was found in the AgNPs 0.05 mg/dm³ group. The histological analysis showed that AgNPs and silver ions cause an increase in the area of hepatocytes. The highest proliferation index of hepatocytes was found in the AgNP 0.05 mg/dm³ group. Furthermore, AgNPs were found to interfere with spermatogenesis and oogonesis as well as reduce the expression levels of the cat, gpx1a, and sod1 genes in the liver compared with the control group. Based on the results, it can be concluded that exposure to AgNPs causes cytotoxic changes in zebrafish, activates the immune system, negatively affects the process of meiosis in the gonads, and generates oxidative stress.

The poultry industry is looking for the most effective sources of selenium (Se) for commercial use. Over the past five years, nano-Se has attracted a great deal of attention in terms of its production, characterisation and possible application in poultry production. The objective of this study was to evaluate the effects of dietary levels of inorganic and organic Se, selenised yeast and nano forms of selenium on breast meat quality, liver and blood markers of antioxidants, the ultrastructure of tissue and the health status of chickens. A total of 300 one-day-old chicks Ross 308 were divided into 4 experimental groups, in 5 replications, with 15 birds per replication. Birds were fed the following treatments: a standard commercial diet containing inorganic Se in the form of inorganic Se at the level of 0.3 mg/kg diet and an experimental diet with an increased level of Se (0.5 mg/kg diet). The use of other forms of Se (nano-Se) versus sodium selenate significantly influences (p ≤ 0.05) a higher collagen content and does not impair physico-chemical properties in the breast muscle or the growth performance of the chickens. In addition, the use of other forms of selenium at an increased dose versus sodium selenate affected (p ≤ 0.01) the elongation of sarcomeres in the pectoral muscle while reducing (p ≤ 0.01) mitochondrial damage in hepatocytes and improving (p ≤ 0.05) oxidative indices. The use of nano-Se at a dose of 0.5 mg/kg feed has high bioavailability and low toxicity without negatively affecting the growth performance and while improving breast muscle quality parameters and the health status of the chickens.

The use of intensive selection procedure in modern broiler chicken lines has led to the development of several skeletal disorders in broiler chickens. Therefore, current research is focused on methods to improve the bone quality in birds. In ovo technology, using nanoparticles with a high specificity to bones, is a potential approach. The present study aimed to evaluate the effect of in ovo inoculation (IOI) of calcium carbonate nanoparticles (CCN) on chicken embryo development, health status, bone characteristics, and on broiler production results and bone quality. After assessing in vitro cell viability, the IOI procedure was performed with an injection of 500 μg/mL CCN. The control group was not inoculated with CCN. Hatchability, weight, and selected bone and serum parameters were measured in embryos. Part of hatchlings were reared under standard conditions until 42 days, and production results, meat quality, and bone quality of broilers were determined. CCN did not show cytotoxicity to cells and chicken embryo and positively influenced bone parameters of the embryos and of broilers later (calcification) without negatively affecting the production results. Thus, the IOI of CCN could modify the molecular responses at the stage of embryogenesis, resulting in better mineralization, and could provide a sustained effect, thereby improving bone quality in adult birds.