Impact of Supplementing Phytobiotics as a Substitute for Antibiotics in Broiler Chicken Feed on Growth Performance, Nutrient Digestibility, and Biochemical Parameters

SIMPLE SUMMARY: The rapid growth in antibiotic synthesis and the discovery of new classes of antibiotics have led to their wide availability. Antibiotics have begun to be used not only in medicine but also in the agricultural sector. The widespread, uncontrolled use of antibiotics in industrial poultry farming has contributed to the growth of resistant types of pathogenic and opportunistic environmental microorganisms. In addition, the vigorous introduction of antibiotics contributes to the risk of the contamination of livestock products, which are then used in human nutrition with antibiotic residues present. The consumption of poultry products contaminated with antibiotic residues due to antibiotic resistance can be lethal to humans. Therefore, we hypothesize that feed additives based on plant extracts, which can be used as alternatives to antibiotics, can affect the productivity, health status, and quality of poultry products. Our results show that the use of phytobiotics in the diet of broilers had promising effects on the digestibility of feed nutrients and the dynamics of the growth of the live body weight of broiler chickens. ABSTRACT: To determine the level of application and the effectiveness of the use of plant feed additives from sweet chestnut wood extract (Castanea Sativa Mill) in the diet of Cobb-500 cross broiler chickens, four groups were formed via the balanced groups method. The chickens in the experimental groups were supplemented with sweet chestnut wood extract in the main diet rather than a feed antibiotic at an amount of 500 g per ton of compound starter feed and 250 g per ton of grower and finisher in the second experimental group; 650 g per ton of compound starter feed and 325 g per ton of grower and finisher in the third experimental group; and 800 g per ton of compound starter feed and 400 g per ton of grower and finisher in the fourth experimental group. Supplementation with phytobiotics led to an increase in the digestibility of the dry matter in the second and third groups compared to the first experimental group. Furthermore, broiler chickens supplemented with a medium dose of phytobiotics revealed a significant difference in both crude protein and fiber when compared to the second experimental group (91.95% and 12.11% vs. 88.98% and 10.07%, respectively). The preslaughter weight of the birds in the phytobiotics supplemented groups was higher than in those fed with the lowest dosage of phytobiotic by 5.47%, and the difference was significant. There were no significant differences in terms of the blood biochemical parameters between the groups. In summary, the inclusion of plant feed additives from sweet chestnut wood extract as a substitute for an antibacterial drug in the diet of broiler chickens did not deteriorate the blood biochemical parameters and improved the intensity of the nutrient digestion process. As a result, it enhanced the quality indicators of the broiler carcass during the entire growth period.