Comparative Assessment of the Microbial Composition of the Rumen of Cattle and Small Ruminants

The aim of the work was to study and compare the microbial composition of the rumen of cattle and small ruminants for further evaluation of the possibility of using microorganisms that improve ruminal metabolism. For the studies, samples of rumen contents were collected from small ruminants of different genotypes and Simmental cattle in compliance with aseptic requirements, respectively, through a fistula and after slaughter. The main groups of microorganisms were isolated by seeding the sample volume onto dense differential diagnostic media with subsequent identification. The highest number of Bifidobacterium sp. (6.13 ± 0.64 Log₁₀ CFU/mL), Lactobacillus sp. (6.18 ± 0.06 Log₁₀ CFU/mL), Enterococcus sp. (5.49 ± 0.21 Log₁₀ CFU/mL), and yeast-like fungi (3.47 ± 0.15 Log₁₀ CFU/mL) were found in the rumen contents of Romanov sheep compared to other groups of small ruminants and cattle. The lowest amounts of Lactobacillus sp. (6.13 ± 0.64 Log₁₀ CFU/mL), Enterococcus sp. (6.13 ± 0.64 Log₁₀ CFU/mL), and lac+ and lac-E. coli (6.13 ± 0.64 Log₁₀ CFU/mL) were observed in the rumen contents of small ruminants of the genotype 1/16 argali (A) × 3/16 Romanov (R) × 8/16 Kathadin (K). The ratio of lac- to lac+ E. coli in sheep of groups R, R × Karachaevskaya (Kar), R×K, A×R, and 1/8A×3/8R×4/8K was at the same level. In cattle, the value of this indicator was 0.92; that in small ruminants of the genotype 1/32A×7/32R×8/32 mouflon (M)×16/32K was 4.64. At the same time, small ruminants of this genotype had the highest number of bacteria of the genus Ruminococcus and there were significantly (p ≥ 0.05) more of them in cattle than in the rumen of Romanov sheep. The maximum amount of E. coli in the experiment (4.65 ± 0.44 Log₁₀ CFU/mL) was found in the rumen of Romanov sheep, with a ratio of lac+ and lac-E. coli of 1.08. The genotype of animals affects the ratio of bacteria in the rumen contents. From the rumen fluid, 21 strains of Rhodotorula and Candida yeasts were obtained.