Genital mycoplasmosis in cows is a disease accompanied by a latent course, which complicates its timely diagnosis and the appointment of adequate therapy. The nonspecific symptomatology of mycoplasmosis, combined with periods of asymptomatic course, leads to the development of functional and morphological changes in the organs of the reproductive system of cows, resulting in infertility. Monitoring studies of livestock farms in the North-West region of the Russian Federation have shown that infection of the genitals of cows with mycoplasmas can be from 20 to 40% of the livestock. Moreover, there is a clear relationship between the high infection rate of the livestock and low reproduction rates. In this regard, livestock enterprises incur significant economic damage. One of the important mechanisms preventing the introduction of various pathogens into the reproductive tract is the resistance of the vaginal mucosa. Among these factors, the most important role is assigned to vaginal autoflora, epithelial desquamation, phagocytosis, acidity of vaginal secretions, the content of immunoglobulins, lysozyme and a number of other nonspecific protective factors in it. We studied the changes in the immuno-biological characteristics of vaginal secretions in the subclinical course of genital mycoplasmosis. Healthy cows with a negative PCR test for Mycoplasma spp. were selected for the study. and infected with Mycoplasma spp., without clinical signs of vaginitis. In both groups of animals, the concentration of hydrogen ions, the activity of lysozyme and immunoglobulins of the classes IgG, IgM, IgA and sIgA were determined in the vaginal secretions. Despite the fact that the persistence of mycoplasmas in the vagina is not accompanied by pronounced clinical signs of vaginitis, but the state of protective factors the mucous membrane undergoes significant changes. The conducted studies made it possible to establish that the long-term presence of mycoplasmas in the vagina of cows is manifested by a significant increase in the concentration of hydrogen ions by 41% and a decrease in the lysozyme activity of vaginal secretions by 2 times, that is, inhibition of the main factors preventing the colonization of mucous pathogenic microflora is observed. In addition, there is a redistribution of classes of immunoglobulins in the vaginal secretion. This is manifested by a significant increase in the content of IgM and sIgA against the background of a tendency towards a decrease in IgA. The noted changes in aggregate create favorable conditions for the introduction of secondary microflora and the development of bacterial-mycoplasma vaginitis, aggravating morpho-functional changes in the reproductive tract and increasing the risk of infertility.
One of the negative factors of ionizing radiation on the body is the formation of active oxidants, which are protected by the antioxidant system. The effect of high doses of radiation on the antioxidant system of animals has been studied well, but there is not enough information about the long‐term effects of low doses. The study of the effect of pre‐threshold radiation doses on the main indicators of antioxidant protection of cattle was the purpose of our research. The research was carried out in JSC "Osminskoye" of Slantsevsky district and JSC "Plemzavod " RAPTI" of Luga district of Leningrad region on healthy lactating cows aged 3–4 years in the amount of 8 heads from each farm. Radio ecological characteristics of agricultural land JSC "Osminskoe" was as follows‐the density of radioactive contamination of the soil on 137Cs more than 1 Ci/km2, the power of the exposure dose on the ground 35–48 μr/h. Similar indicators of land in JSC "Plemzavod" RAPTI " were less than 0.5 Ci/km2 and 6–19 μr / h. Both farms use their own fodder base (hay, silage, root crops), concentrated feed produced by JSC "LKKZ", the animals are kept in summer walking, which allows us to talk about a similar dose load due to external and internal irradiation. In cows, catalase activity was determined in serum, and malone dialdehyde concentration and superoxide dismutase activity were determined in plasma. The results of the study showed that the activity of superoxide dismutase in cows from JSC "Osminskoye" was 4.15±0.46 U/mg Hb, catalase ‐ 14.54±1.03 mkat/l, and the level of Malon aldehyde ‐ 3.71±0.68 μmol/l. Similar indicators in animals from JSC "Plemzavod "RAPTI" were as follows ‐ 6.3±0.75 U/mg Hb, 9.77±0.62 mkat/l and 2.23±0.12 μmol/l. Intergroup differences of the studied indicators were statistically significant. Analyzing the results of the study, we can say that chronic stimulation of the antioxidant system by active oxidants leads to a decrease in the level of superoxide dismutase in cows by 34.1%. Probably, as compensation, there is an activation of other enzymes, in particular, an increase in catalase activity by 1.5 times. However, the compensatory capabilities of other elements of the antioxidant system are not able to fully neutralize free radicals, as evidenced by an increase in the concentration of malon dialdehyde by 66.4%.The study shows that cows long‐term in conditions of higher pre‐threshold doses of external and internal radiation occurs chronic oxidative stress, manifested by an imbalance of individual links of the antioxidant system.
Inflammatory diseases of the genital tract have a significant effect on reducing the reproductive function of cows. These diseases cause significant economic damage to livestock farms in the Russian Federation. Among the many causative agents of infectious and inflammatory diseases of the genitals, representatives of the Mycoplasmataceae family occupy a special place, which is associated with the peculiarities of their biology. Therefore, the study of their influence on microecology and the protective properties of the vagina is an urgent task. The studies were carried out in JSC “Osminskoye” of the Slantsevsky district of the Leningrad region on non‐pregnant cows 3‐4 years old. Was formed 2 groups of 8 animals each. The first group is healthy cows in which the PCR test for Mycoplasma spp. was negative. The second group consisted of cows with a positive PCR test for Mycoplasma spp., Without pronounced clinical signs of vaginitis. M. bovigenitalium was identified by the serological method in these animals. In both groups of animals, vaginal secretions were collected from the vaginal wall using a special spoon in the cervical region. In the obtained secretion, the content of immunoglobulins of the classes Ig G, Ig M, Ig A and secretory immunoglobulin A (sIgA) was determined by the method of radial immunodiffusion in a gel according to Mancini. The results of the study show that the total content of immunoglobulins in vaginal secretions in healthy and mycoplasmosis animals was almost the same 0.32 g / l and 0.351 g / l, respectively. However, the distribution of immunoglobulins by class had significant differences. The Ig A concentration in cows with mycoplasmosis was 0.018 ± 0.001 g / l, which was 25% less than in healthy cows ‐ 0.024 ± 0.003 g / l, but the difference was not significant (P> 0.05). The level of Ig G in vaginal secretions in healthy cows and cows with mycoplasmosis was almost the same ‐ 0.19 ± 0.008 g / l and 0.183 ± 0.008 g / l. The content of immunoglobulin M in the vaginal secretion of healthy cows was 0.039 ± 0.002 g / l, while in patients with mycoplasmosis it was significantly higher ‐ 0.054 ± 0.003 g / l and the change was significant (P <0.01). Similar dynamics was observed for secretory immunoglobulin A (sIgA). In healthy cows, its sIgA level was 0.067 ± 0.005 g / l, while in patients with mycoplasmosis it was 43% higher ‐ 0.096 ± 0.007 g / l, and the differences had a high degree of reliability (P <0.001). The results of the study show that persistence of Mycoplasma bovigenitalium in the vagina of cows causes a local immune response, which is manifested by a tendency towards a decrease in Ig A, a significant increase in the levels of Ig M and sIgA, against the background of a stable content of Ig G.
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