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EU banned antibiotic growth promoters (AGP) for farm animals and poultry since 2006 in relation to the problem of drug resistance. This requires alternative products for equally efficient prevention and treatment of certain alimentary poultry diseases. One of the most actual trends is the development of innovative nutritional strategies for poultry providing an effective symbiosis between the host and its intestinal microbiota. The study presented was aimed at the comparative evaluation of productivity, nutritive value of meat, and composition of intestinal microbial populations in broiler chicks fed different diets (corn - soybean meal, wheat - sunflower cake, barley - sunflower cake) supplemented with AGP or a probiotic (cellulolytic and lactic microorganisms). In three trials straight-run Cobb 500 broilers reared from 1 to 36 days of age were fed these diets supplemented with bacitracin from 1 to 29 days of age (control) or probiotic preparation from 1 to 36 days of age (70 birds per dietary treatment in each trial). There were no differences in live bodyweight and carcass yield between the treatments in all three trials. In the two trials with sunflower cake, protein content in breast meat was significantly higher by in birds fed probiotic in compare to birds fed AGP (by 10.0 and 6.8%, p<0.05), while fat content in thigh meat was lower by 12.0% (p<0.05) and 14.1% (p<0.01), respectively. Content of amino acids in meat did not differ. Vitamin content in the poultry meat of the experimental groups was significantly higher compared to control (p<0.001). The resulting concentrations of bacitracin in meat in control treatments (no more than 0.02 U/g) did not exceed local legislative limitations. The substitution of the probiotic for AGP beneficially affected the composition of bacterial populations in the duodenum and cecae determined using T-RFLP analysis. It was concluded that the supplementation of diets with probiotic allows to produce antibiotic-free broiler meat without detrimental effects on the productive performance., (Copyright© GEOTAR-Media Publishing Group.)

Molecular genetic techniques (NGS sequencing and quantitative PCR) were used to determine the composition of the cecal bacterial community of broiler chickens fed with different mixed fodder. The Cecal microbiome exhibited taxonomic diversity, with both typical inhabitants of avian intestine belonging to the families Clostridiaceae, Eubacteriaceae, and Lactobacillaceae and to the phylum Bacteroidetes, and new un- identified taxa, as well as bacteria of the families Lachnospiraceae and Ruminococcaceae, which were previ- ously considered restricted to the rumen microflora. Contrary to traditional concepts, enterococci and bi- fidobacteria were among the minor components of the community, lactate-fermenting species were absent, and typical avian pathogens of the genus Staphylococcus were detected but seldom. Members of the family Suterellaceae and the genus Gallibacterium, which are responsible for avian respiratory infections, were also detected. Significant fluctuations of abundance and composition of microbial groups within the cecal com- munity and of the parameters of broiler productivity were found to occur depending on the feed allowance. Cellulose content in the feed had the most pronounced effect on the composition aid structure of bacterial communities. Decreased cellulose content resulted in a decrease of bacterial abundance by-aii order of mag- nitude and in increased ratios of members of the phylum Bacteroidetes and the family Clostridiaceae, which possess the enzymes degrading starch polysadcharides. Abundance of the normal inhabitants of avian intes- tine belonging to the genus Ldctobacillus and the order Bacillales decreased, while the share of Escherichia and members of the family Sutterellaceae increased, including some species capable of causing dysbiotic changes in avian intestine. No significant change in abundance of cellulolytics of the families Ruminococca- ceae, Lachnospiraceae, and Eubacteriaceae was observed.