Microbiological indicators in the rumen of sheep when fed different levels of concentrates

Relevance . This article presents the results of a study ofthe effect offeeding different levels of concentrates on the rumen microbiota of sheep. Methods . The experiment was carried out on the basis of the physiological yard of the L.K. Ernst Federal Research Center for Animal Husbandry on Romanov sheep with chronic rumen fistulas according to Basov. The experiment was conducted using the method of groups of periods, the duration of each period is 30 days (n = 6). In the first period, the sheep received a hay-concentrate diet containing 20% concentrates, in the second — 30%, in the third — 40% of nutritional concentrates. At the end of each balance experiment, samples of ruminal contents were taken from all animals (n = 6) for a genetic study of the rumen microbiota. Results . Increasing concentrates to 40% resulted in a 6% and 7.5% reduction in total microbial mass compared with 20% and 30% concentrate diets, respectively. The amylolytic activity of the rumen after feeding gradually increased from 12.73 to 14.21 U/ml when the diet was changed to a more concentrated one. With an increase in the proportion of concentrates, the population of enterococci increases with a maximum at 30% of concentrates. The most intensive growth of the lactobacilli population is observed when feeding 30% concentrates (4.78∙10 5 CFU/ml versus 3.18∙10 5 CFU/ml at 40%). The ratio of QMAFAnM before and after feeding remained constant with a pronounced maximum at 30% concentrates. It was not possible to detect a consistent pattern in the change in the number of fungi in the rumen at different levels of concentrates in the diet. Metagenomic analysis showed an increase in the number of Lactobacillus spp. , Bacteroides spp. , Blautia spp. , Streptococcus spp. , Roseburia inulinivorans , Prevotella spp. , with a decrease in the number of Bifidobacterium spp. , Methanobrevibacter smithii , Methanosphaera stadmanae , Ruminococcus spp. in ruminal contents with an increase in concentrates by 20%, 30% and 40%. The highest contamination with microorganisms is observed when feeding animals 30% concentrates.