It has been scientifically proven that the microbiota is not only the most ancient and habitable inhabitant of the Earth, but also is in complex associative interactions with a macroorganism. Most authors are unanimous in the opinion that the interaction between the human body and its microflora can be positive and negative, characterized by the aggression of the autoflora against the host organism. In a healthy organism, the symbiosis between the macroorganism and the microbiotics friendly with it is realized on the principle of commensalism. Through this, a dynamic equilibrium is realized in the ecosystem "macroorganism-microbiota-environment", defined in the literature as "eubiosis." Disharmony in a holistic and stable intestinal ecosystem is treated as a dysbacteriosis. In recent years, a more correct term "dysbiosis" is used in medical works on microbiotic.

Analyzing the sources of scientific veterinary literature, we should note a rather narrow understanding by researchers of the significance of dysbiosis and its pathological consequences, mainly in the cause-and-effect relationship with digestive disorders. According to the same journal, "Science" has established a significant effect of the intestinal microbiota on the functioning of the entire human body, not excluding the activity of the brain.

This discovery served as the basis for the formulation of the concept of metabolic dysbiosis, in accordance with which, with an overwhelming majority of diseases of internal organs, there is a violation of intestinal microbiocenosis.

In order to detail knowledge of dysbiosis, a number of attempts were made to classify it. The basis for the systematization of knowledge was laid down by various assessment criteria for the violation of intestinal microecology.

In the opinion of most microbiologists, the most successful is the classification proposed by IB. Kuvaeva and K.S. Ladodo (1991), according to which violations of eubiosis are presented depending on the degree of dispersion of the microbial composition of the intestine and are ranked from 1 to 4 level, characterizing the depth of the revealed changes.

Most researchers are unanimous in recognizing the fact that the features of the strategy of treating people with diseases associated with dysbiosis, regardless of its etiopathogenesis, largely depend on the degree of shift of mobile equilibrium in intestinal normobiosis.

In our opinion, the existing medical classifications of dysbiosis can not be extrapolated to animals, nor can it serve as a basis for scheduling treatment regimens, since the inter-specific quantitative and qualitative characteristics of the microbiota, as well as its factor sensitivity, are different.

Compiling the scientific heritage in the field under discussion, the results of our own findings, as well as the numerous opinions of practitioners about the ambiguous therapeutic effectiveness of biotic drugs, it should be noted that the lack of a distinct clinical veterinary classification of dysbiosis does not allow practicing veterinarians to develop scientifically based schemes for controlling gastrointestinal diseases in animals.

Analyzing the results of a coprological study of calves with abdominal enteritis and dyspepsia, at the beginning of the experiment, a significant decrease in the representatives of the indigenous microflora was observed on average by 31%, and the growth of opportunistic microorganisms by more than 50% (p≤0.05). Along with this, from the faeces of diseased calves, pathogenic strains were isolated, not related to the symbiontic microflora of the large intestine. The isolated staphylococci showed hemolytic properties, the increase in the coliform population was mainly due to strains with low enzymatic activity. Analyzing the obtained set of digital characteristics of dysbiosis and the severity of its clinical signs, we believe that at the beginning of these diseases intestinal dysbiosis has 3 (severe) degree of severity.

A day later, in groups of calves with abdominal enteritis, intergroup differences in the dynamics of representatives of intestinal symbiosis were noted. Thus, in the first group, already at this stage, an intensive significant (p≤0.05) growth of bifido- and lactoflora was observed on average 35%, in the second to 8.64 and 8.15 lg CFU/g (vs. 10.12 and 9.32 lg CFU/g in the control), which was an intergroup difference of 19%.

Regarding the conditional pathogens and pathogenic strains, a significant (p≤0.05) decrease in both groups was found, determined, apparently, by the different sensitivity of microorganisms to antimicrobial agents. Thus, the intensive proliferation of the indigens in the first group in the intergroup comparison, even with similar dynamics of some conditioned pathogens, allows us to state a different degree of changes in the experimental groups. Following this logic, in the first group we classified 1 (light), and in the second group – 2 (medium) degree of dysbiosis.

By the fifth day of the experiment, the majority of calves from the first group, who had abdominal enteritis and dyspepsia, had no clinical signs of digestive disorders. The results of the study of feces of young animals with abdomazoenteritis show a significant (p≤0.05) numerical prevalence of bifido- and lactobacilli in calves of the first group, both in comparison with the control and with the second group by 1-2 orders of the logarithm. A statistically insignificant intergroup difference in the level of anaerobic bacilli was established, and by the number of streptococci it was 1 order of the decimal logarithm, with prevalence in the calves of the second group. Based on the analysis of the results obtained, in the calves of the second group, taking into account the classification criteria of dysbiosis, at the time of the study, 1 degree of dysbiosis was found, similar in description to that of the first group.

On day 7, the calves of the second group had no clinical signs of disease, the values of the studied parameters were balanced in the 7-10% range of insignificant difference with the corresponding controls (р≥0,05), pathogenic strains of microorganisms were not revealed. It should be noted that we have established a similar dynamic of intestinal microbiota in calves with dyspepsia. The difference was that the degree of homeostasis of the indices was less intense than in young animals with a diagnosis of abomasoenteritis.

The presented classification was based on the results of our experiments, during which 3 degrees of dysbiosis were diagnosed. According to the medical literature, intensive proliferation of conditioned pathogens against the background of a decrease in colonization resistance of the colon can lead to the translocation of opportunistic microflora from the intestinal biotope into the internal environment of the organism, which is classified as the 4th degree of dysbiosis by the authors of scientific works. In the course of our research, similar results were not obtained. However, exclude such a trend is impossible and this issue requires additional research.

Thus, on the basis of the analogies performed for different nosological units having a single profile orientation, it is possible to characterize dysbiosis in the staging of its development, classifying it into 3 degrees of severity. The degree of manifestation of changes in the quantitative and qualitative composition of the intestinal microbiota, apparently, determines the pathogenetic difference in the course and duration of the diseases under discussion in the experimental groups.

Key words: dysbiosis, classification, cattle, abomasoenteritis, dispepsia