The Effect of a Symbiotic Preparation Under Different Schemes of Therapeutic and Preventive Measures in Broiler Chicken Rearing

The aim of the study is to comparatively evaluate the effect of the synbiotic drug Vetastar on the physiological parameters, as well as on the productivity of broiler chickens with various schemes of its inclusion in the LMP. The paper presents the results of the experiment on the use of the synbiotic Vetastar in various schemes of therapeutic and preventive measures (LMP) for day-old broiler chickens of the Smena 9 cross (n = 95). The growing period was 35 days. The chickens were divided into three groups: the control group received the standard LMP scheme with antibiotics (Coliflox and Levoflon 15 %); experimental group 1 (EG1) – the standard scheme followed by a course of synbiotic; experimental group 2 (EG2) – a scheme where the antibiotic was completely replaced by a course of synbiotic. The addition of a synbiotic after a standard antibacterial course (OP1) resulted in the highest average live weight (2,366 g), average daily weight gain (66.2 g), and feed conversion ratio (1.69 kg/kg), significantly exceeding the control. Replacing the antibiotic with a synbiotic (OP2) resulted in 100 % survival of the herd, a significant increase in the abundance of autochthonous microflora: lactobacilli (up to 1010 CFU/g) and bifidobacteria (up to 108 CFU/g) in the intestine, as well as stimulation of T-cell and humoral immunity, as evidenced by a significant increase in the level of cytotoxic T-lymphocytes and B-lymphocytes. Bacteriological analysis confirmed the synbiotic's normalizing effect on the microbiome, manifested in a reduction in the frequency of isolation and bacterial load of opportunistic microorganisms. The immunomodulatory effect was regimen-dependent. In the OP1 group, increased nonspecific resistance (increased phagocytic reserve) was observed, while in the OP2 group, a balanced activation of specific immunity was observed. The results confirm the high efficacy and potential of partial replacement of antibiotics with synbiotics for optimizing treatment and preventive measures, improving poultry health, creating a balanced microbiome, and increasing productivity in broiler poultry farming.