Mixtures of biologically active substances of oak bark extracts change immunological and productive indicators of broilers

To date, numerous studies are focused on searching for alternatives to antibiotics with similar antimicrobial and growth-stimulating effects that do not cause bacterial resistance and potential side effects for animals. Promising phytogenic compounds have been also recognized as potential alternatives to antibiotics in feeds. One of the problems of phytogenic compound use is the unstable chemical composition of plant extracts, depending on the conditions of growth, distribution area and other factors, so the question arises of extracting some substances with the known properties or designing their compositions. In this paper, it has been shown for the first time that a dietary composition of biologically active substances of Quercus cortex helps to maintain productivity and improves the immunomodulating state of Smena 8 poultry cross broilers. In our experiment, a composition of substances (CS) extracted from Quercus cortex and chemically synthesized («Acros Organics B.V.B.A.», Belgium) was used, including 2-n-propylresorcinol (98 %, AVH27024); 4-hydroxy-3-methoxybenzaldehyde (99 %, AC14082-1000); 7-hydroxycoumarin (99 %, AC12111-0250); 3,4,5-trimethoxyphenol (98.5 %, AC18914-0050); scopoletin (95 %, AC30290-0010); coniferyl alcohol (98 %, AL22373-5) with a confirmed anti-QS effect. A total of 120 broiler chickens aged 7 days were divided into 4 groups ( n = 30) by analogue method. Control group was fed with the basic diet (BD). BD + CS 1 (1 ml/kg of live weight), BD + CS 2 (2 ml/kg of lw), and BD + CS 3 (3 ml/kg lw) were used for group 1, group 2, and group 3, respectively. In the experimental groups, as compared to the control, the number of blood leukocytes increased by 19.2-28.5 % (P ≤ 0.05), blood lymphocytes were higher by 24.4, 36.2 % (P ≤ 0.05) and 44.0 % (P ≤ 0.05), blood monocytes were higher by 23.5, 23.5 and 29.4 % (Р ≤ 0.05), and blood granulocyte counts were higher by 12.3 % (Р ≤ 0.05), 5.7 and 9.5 %. The blood ALT activity in the group 2 and group 3 exceeded the control value by 13.2 % (P ≤ 0.05). The level of GGT tended to decrease in the group 2 and group 3, along with a significant decrease in LDH by 17.6-22.5 % (P £ 0.05). The intake of the CS as a feed additive was accompanied by an increase in blood SOD levels in the test groups, the highest concentration being observed in the group 1 (95.3 %). The catalase indices had similar patterns. Dietary composition of biologically active substances promoted a 16.4 % increase (P ≤ 0.05) in blood b-lysine levels in the group 1. Within 4 weeks, the dietary CSs led to an increase in the live weight of the poultry of the group 2 and groups 3 by 12.6-15.0 % (P ≤ 0.05) when compared to the group 1. In the group 1, the birds grew more rapidly with a 100 % survival rate of the herd, in contrast to the remaining groups with the survival index of 71 to 85 %. These contributed to an insignificant increase in the bird live weight at the end of the experiment (day 42) by 1.9 % (P ≥ 0.05) compared to the control group. Thus, feeding broiler chickens with the composition of bioactive substances in the initial concentration helps to maintain productivity and improve the immunomodulating state of body.