Katunskaya, Maima village, Altai Republic, 649100 Russia A b s t r a c t Optimal physiological state and further performance of genetically determined production efficacy in young farm animals and poultry significantly depend on application of probiotics used to correct gut microbiota number and composition, and enough input of essential microelements such as Se. <...> Their mutual effect on metabolism, and animal and poultry productivity is under special consideration. <...> An impact of probiotis on mineral metabolism is being reported in detail while the study of the Se metabolism in macroorganism as influenced by the probiotic preparation are extremely restricted. <...> Blood morphology parameters, being universal in character and easy evaluated, are good to estimate the metabolic state. <...> In this paper we report the results of estimating blood erythrocyte and leukocyte number, hemoglobin levels, erythrocyte sedimentation, hematocrit, an average total and percentage hemoglobin level per erythrocyte, and an average erythrocyte size in groeing broiler turkeys ( ) of But 8 cross on day 50 and day 100 of life. <...> Poultry was reared under the commercial farm conditions (Yasnogorskii brunch of ALPI agro holding, Kemerovo Province). <...> Russian Vetom 1.1 probiotics, Sel-Plex («Alltech», Ireland) which contains organic Se compounds and their combination were administrated to chicken additionally to the standard basic diet. <...> All tested preparation and schemes had no negative impact on studied blood parameters. <...> There was a clear tendency to increased erythrocyte and leukocyte numbers, together with hemoglobin level and hematocrit value though the parameters remained within physiological limits. <...> The positive effect of synbiotics (i.e., probiotics and Se combination) was more pronounces. <...> The growing broiler turkeys administrated with dietary synbiotics were superior to those fed with probiotics or SelPlex. <...> Optimization of physiological processes in young farm animals and poultry is largely achieved by probiotics used to correct the species and quantitative composition of gastrointestinal microflora [1-4]. <...> In addition, a sufficient input of essential trace elements, such as selenium, is one of the most significant factors contributing to the realization of genetic potential in poultry. <...> The combined effect of probiotics and selenium on metabolism and productivity becomes the subject of the special attention of researchers. <...> Selenium deficiency causes the symptoms <...>