Immunological status of fetal fluids in cows of different genotypes of the Black-and-White breed

Abstract

The immunobiological properties of allantoic and amniotic fluids in cattle at different stages of gestation (3–7 months), taking into account the animals' genotypes, were investigated. The aim of the study was to assess the levels of immunoglobulins G and M, lysozyme concentration and activity, as well as the bactericidal activity of the fetal fluids in order to elucidate the mechanisms of nonspecific immune protection of the fetus within the mother–fetus system. The experimental material consisted of four groups of pregnant Black-and-White cows, including hybrid genotypes with different proportions of Holstein blood. The concentrations of IgG, IgM, as well as lysozyme and bactericidal activity of the fetal fluids, were determined using standard generally accepted methods. The results demonstrated that IgG, IgM were absent or detected in trace amounts in the majority of fetal fluid samples, indicating limited activity of adaptive humoral immunity during the intrauterine period. The bactericidal activity of the fluids was low and inconsistent, whereas lysozyme remained a stable and dominant factor of nonspecific humoral defense. Its concentration in allantoic and amniotic fluids significantly exceeded the levels observed in the blood serum of both fetuses and dams, suggesting autonomous synthesis of this enzyme by fetal organs and immunocompetent cells. The highest lysozyme values were recorded at the fifth month of gestation, and a tendency toward increased enzyme levels was observed in animals with a higher proportion of Holstein blood, indicating a possible genetic determination of this parameter. The obtained data confirm the leading role of lysozyme in the formation of the primary immune barrier of the fetus and in maintaining physiological immune balance within the fetal environment. Within the framework of the One Health concept, these findings are of practical importance for reducing the risk of intrauterine infections, improving neonatal viability, decreasing the need for antimicrobial therapy, and ensuring the safety of livestock products. Therefore, the immunological properties of allantoic and amniotic fluids represent a key factor in normal fetal development and reproductive health in cattle.