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 primary objective of this study was to investigate the impact of a phytogenic additive (PA) in broiler chickens’ diet on production, physiochemical parameters, and the profile of volatile organic compounds present in broiler chickens’ meat. The experiment was conducted in a commercial chicken house, where Ross 308 broiler chickens were divided into two groups, each consisting of 65,000 broilers. One group was fed a diet supplemented with 100 ppm of PA throughout the rearing period. The primary chemical composition of the meat and its physicochemical parameters were determined. A visual assessment of breast muscles for defects and volatile organic compounds were evaluated using an electronic nose system. No statistically significant differences were shown in the production performance of the chickens; while summarizing all production parameters, a higher EPEF index of 31 points in the experimental group was highlighted. Breast muscle quality showed differences in drip loss and WHC (p ≤ 0.01) in favor of the experimental group, and a lower cutting force value (p ≤ 0.05) was found for breast muscles from the experimental group. The group also had a lower proportion of muscles with a white striping defect, and the results of volatile organic compound profiling showed the most aroma units.

The study evaluated the effects of crude fibre concentrate supplementation on final body weight, mortality, feed conversion ratio, European Production Efficiency Factor, European Broiler Index, welfare parameters, colony-forming units of selected caecal bacteria (Enterobacteriaceae and lactic acid bacteria) and pH of broiler faeces and litter. The study comprised 990 Ross 308 male chicks divided into three groups, a control and two experimental groups, which were given crude fibre concentrate as a feed supplement. On the thirty-fifth day of rearing, the birds’ welfare scores were evaluated, and 2 g of cecum was collected post-mortem from six chickens in each group. Subsequently, a series of ten-fold dilutions of the material was prepared, followed by cultures and measurement of pH in the faeces and litter. The inclusion of crude fibre concentrate resulted in a beneficial impact on the ultimate body mass (p ≤ 0.001), welfare standard (p ≤ 0.001), and quantity of colony-forming units of lactic acid bacteria (p ≤ 0.05) within the cecum. Furthermore, it had a positive influence on lowering the pH levels of both faeces and litter (p ≤ 0.05).

This study aimed to investigate the effects of a Standardized Natural Citrus Extract (SNCE) on broiler chickens’ growth performance, gut health, carcass quality, and welfare. A total of 756 one-day-old Ross 308 males were randomly assigned to two groups: a control group (CTL) fed with a standard diet, and a citrus group (SNCE) fed with the same standard diet supplemented with 250 g/ton of feed of SNCE. Growth performance was recorded weekly until d 35, while mortality was recorded daily. The feed conversion ratio (FCR) and European Efficiency Index (EEI) of broiler chickens were also calculated weekly. At day 35, 10 birds per group were randomly selected for slaughter performance. In parallel, broiler chickens’ welfare was assessed according to the Welfare Quality Assessment Protocol. Caecal digest was also collected post mortem for short-chain fatty acids (SCFA) analyses, and jejunum samples were collected for ex vivo gut permeability assay. SNCE dietary supplementation enhanced broiler chickens’ performance, i.e., final bodyweight and EEI, compared to the CTL group. The carcass weight was also significantly higher in the SNCE group. In addition, the fat percentage was lower in the SNCE group. Regarding broiler chickens’ welfare and gut health parameters, Footpad Dermatitis (FPD) and gate score were also lower in birds supplemented with SNCE. The SCFA measurement showed a lower concentration of iso-butyric acid, iso-valeric acid, and total putrefactive SCFA in the SNCE group. The differences in gut permeability measured as TEER value indicate that using citrus extract lowered the risk of gut inflammation. This study provides valuable insights into the mechanisms of action that may underlie the observed effects of SNCE on performance, as demonstrated in this study and others. These effects could potentially be attributed to the reduction in inflammation and the enhanced utilization of nutrients. Further studies are needed to confirm these results.