This review article summarizes current understanding of the microbiota development in neonatal mammals based on the results of modern experimental studies in animals focusing on three aspects: initial colonization, microbiota effect on the immune function of the developing newborn animal intestine and external factors influencing the microbiome shaping during the juvenile period. The presented study results confirm that the microbial landscape correction is the most important factor for animal health improvement since healthy microflora contributes to the intestinal infection frequency and intensity reduction, and this, in turn, minimizes the use of antibiotics. The microbiome is known to have an impact on the immune system development, metabolic processes and even on the ethology, so an atypical microbial population can cause immune and metabolic disorders. The active interaction between microorganisms and the host organism begins already at birth. Even different modes of delivery (caesarean or vaginal delivery) may determine the initial colonization of the newborn. The animal genetics, nutrition and environment also influence the intestinal microbiota development. In this regard, further studies of probiotics are important to understand their efficacy for diarrhea prevention and treatment, their use as an alternative to antibiotics as well as for enhancement of the animal resistance to stress factors.

Bovine respiratory diseases are widespread and present a multifactorial and variable etiology. However, several aspects of their origin remain understudied. Therefore, the objective of the present study was to investigate the effect of changes in calves’ keeping conditions on their clinical state in terms of microbiocenosis in their respiratory tract. The study was conducted in the winter season, with 37 healthy calves, 5-6 months in age, which were transferred from calf barn number 1 with favorable conditions to calf barn number 2 having a similar design as that of the previous barn but with unfavorable microclimatic parameters (drafts, low temperature, and high humidity). Within 7-9 days after their transfer to the other barn by a veterinary specialist, 54.1% of the calves were diagnosed with catarrhal bronchopneumonia. On day 10, all animals were slaughtered and dissected. Mucus samples for bacteriological analysis were obtained from the mucous membrane of seven sections of the respiratory tract of animals. In all calves, the highest degree of contamination was observed in the first half of the ventral nasal passage (84.9 ±24.46% in healthy calves and 85.7 ±18.55% in sick calves). In healthy calves, the degree of contamination in the front of the choanae was lower by a factor of 56.2% (P = 0.000059) compared to sick calves, and this value continued to decrease when moving toward the lower respiratory tract until the complete disappearance of the bacteria.

The largest number of currently produced drugs for the treatment of mastitis in lactating cows contain antimicrobial components (antibiotics) as active substances. The studies were carried out on Red-Motley Holstein cows, in which subclinical mastitis was diagnosed. The animals selected for the experiment were divided into three groups. The first group included 8 animals, they were not treated and served as a negative control. In the second group, 10 cows were selected for treatment with Biferon-B for three days once a day at a dose of 10 ml. per animal. The animals of the third group were simultaneously administered interferon-λ and BiferonB intramuscularly, 10 ml each during those days. According to the results of clinical studies, it was found that no recovery was recorded in the animals in the negative control group. In the group of animals where Biferon-B was used, the efficacy of treatment was 60.0%, and with the combined use of Biferon-B and interferon-λ, the effect of treatment was 83.3%. In these animals, the number of somatic cells decreased by 14.3 times, the concentration of neutrophils – by 2.6 times, the amount of total Ig - by 67.5%, CIC - by 61.5%, against the background of an increase in the number of lymphocytes by 6.0 times, monocytes - by 2.1 times and lysozyme - by 45.3%, and the bacterial contamination of the udder secretion also decreased to 0.08 thousand CFU/ml, which was by 120 times less compared to the initial state. Only Escherichia coli has been isolated from the udder secretion in 20.0% of cases that confirms the clinical efficacy of the treatment.

The doctrine of the normal microflora of the human and animal body is currently in the focus of attention of clinical microbiologists and a wide range of clinical specialists. It is known that the microflora of the vagina depends on many factors of the internal and external environment, therefore, it is now considered to be an ecosystem with a unique set of mechanisms that ensure its resistance to foreign microorganisms and support reproductive health. The aim of the study was to study changes in vaginal microbiocenosis in cows during different periods of pregnancy. The object of the study was clinically healthy cows (n=10) of a redmottled breed (holshitinized), and the subject of the study was cervical–vaginal mucus. On the 150-160, 210-220 and 260-265 days of pregnancy, mucus samples were taken from cows using sterile probe tampons for bacteriological studies. It was found that representatives of the normoflora, as well as conditionally pathogenic and pathogenic microflora were present in the vaginal secretions of animals of all periods of pregnancy. However, the total bacterial contamination of the genital tract in cows in the first half and second half of the third trimester of pregnancy was characterized by its decrease by 29.2 and 33.3%, respectively, relative to the data obtained in the second trimester. It should also be noted that by the second half of the third trimester of pregnancy, there is an increase in obligate normoflora due to lacto- and bifidobacteria by 27.1% and 4 times, respectively, with the predominance of the genus Lactobacillus in quantitative terms. Against this background, the amount of transient microflora decreased by 34.2-57.1% (P0.05).

It is known that the bacteria of the genus Staphylococcus are among the most common bacterial pathogens in the pathogenesis of mastitis. Detailed and comprehensive knowledge of the metabolism of Staphylococcus is necessary to understand its pathogenesis. The aim of the study was to identify the metabolic pathways of S. aureus bacteria isolated from the milk of the cows with mastitis. A total of 88 metabolic pathways were identified for the studied S. aureus. Biosynthesis pathways were strongly dominated in bacteria, the most common of which were biosynthesis of 5-aminoimidazole ribonucleotides, biosynthesis of L-lysine, L-threonine and L-methionine II, biosynthesis of coenzyme A, biosynthesis of L-isoleucine and biosynthesis of uridine monophosphate. A pathway for the synthesis of Nacetylglucosamine has been found in S. aureus bacteria. This pathway may be important for bacterial virulence. The pathway of peptidoglycan III biosynthesis has been discovered. This pathway was previously described for Mycobacteriaceae. In addition, in the cells of S. aureus there have discovered mixed acid fermentation genes, which are more typical for representatives of Enterobacteriaceae. According to the sequencing results, it has been revealed that various folate metabolism pathways are widely represented in S. aureus cells, emphasizing its obvious great importance for this type of bacteria.