Effects of inflammatory processes in the reproductive tract on the physicochemical characteristics and mass distribution of uterovaginal mucus components in cows

The reproductive performance of cows was monitored under the conditions of a livestock farm belonging to a private agricultural enterprise. During April–June, uterovaginal mucus (UVM) samples were collected from 14 Ukrainian Black-and-White Holsteinized cows aged 3–9 years on Days 1–3 of estrus. Based on visually assessed characteristics of color and viscosity, as well as measured parameters of volume and mass of combusted volatile (VS), thermostable (TS), organic (OS), water-soluble (WSS), and water-insoluble substances (WIS), the animals were divided into a control group (n = 9) and an experimental group (n = 5). The obtained results represent the first stage of the study and are aimed at identifying changes in UVM volume, physical characteristics (color and viscosity), evaporated water mass, total dry residue (DR) mass, as well as absolute and relative ratios between volatile and thermostable fractions of the dry residue. The average volume of samples indicated that cows in the control group secreted 10–40 cm³ of UVM, whereas cows in the experimental group secreted 8–21 cm³. Control group samples were viscous or highly fluid, transparent and/or light gray in color, and free of blood and purulent impurities. In contrast, samples from the experimental group were watery and weakly fluid, contained blood and purulent admixtures, and were light gray and/or yellow-green in color. These differences in physical properties were accompanied by changes in water content. During Days 1–3 of estrus, UVM from the experimental group contained 1.4-fold less water (H2 O) (14.12 vs. 20.20 g) and 1.6-fold less water-insoluble matter (WIS) (0.1209 vs. 0.1935 g) compared with the control group. Additionally, the distribution of dry residue components demonstrated that dehydrated experimental samples contained a 1.5-fold higher combined mass of volatile (OS1 ) and thermostable (OS2 ) biologically active compounds compared with controls (0.1409 g vs. 0.2044 g; note: inverse distribution compared to control). The mass distribution followed different patterns between groups: in the experimental group OS1 > WIS > OS2 , whereas in the control group the order was WIS > OS1 > OS2 . These findings suggest that inflammatory processes in the reproductive tract, associated with biologically active compounds (including cytokines, chemokines, leukotrienes, histamine, nitric oxide, and others), may influence the composition of uterovaginal mucus. The combined mass of volatile and thermostable fractions reflects the intensity of these processes and differs between groups. The distribution of mass within the system “water (H2 O) – substances (OS, WIS)” showed wide variability in both absolute (lim M = 0.02–0.4 g; lim Cv = 41–77 %) and relative (lim M = 1–3 %; lim Cv = 7–37 %) indicators. The inflammatory impact resulted in altered ratios of evaporated water to the sum of volatile and thermostable substances (H2 O:(VS+TS)), which in the experimental group was 43:1 compared to 60:1 in the control group (1.4-fold decrease). The H2 O:WIS ratio remained similar between groups and thermostable (OS2 ) biologically active compounds compared with controls (0.1409 g vs. 0.2044 g; note: inverse distribution compared to control). The mass distribution followed different patterns between groups: in the experimental group OS1 > WIS > OS2 , whereas in the control group the order was WIS > OS1 > OS2 . These findings suggest that inflammatory processes in the reproductive tract, associated with biologically active compounds (including cytokines, chemokines, leukotrienes, histamine, nitric oxide, and others), may influence the composition of uterovaginal mucus. The combined mass of volatile and thermostable fractions reflects the intensity of these processes and differs between groups. The distribution of mass within the system “water (H2 O) – substances (OS, WIS)” showed wide variability in both absolute (lim M = 0.02–0.4 g; lim Cv = 41–77 %) and relative (lim M = 1–3 %; lim Cv = 7–37 %) indicators. The inflammatory impact resulted in altered ratios of evaporated water to the sum of volatile and thermostable substances (H2 O:(VS+TS)), which in the experimental group was 43:1 compared to 60:1 in the control group (1.4-fold decrease). The H2 O:WIS ratio remained similar between groups (117:1 vs. 104:1), whereas more pronounced differences were observed in H2 O:VS (OS1 ) (89:1 vs. 201:1; 2.3-fold decrease) and H2 O:TS (OS2 ) (306:1 vs. 501:1; 1.6-fold decrease). Despite wide variability of absolute (g) and relative (%) parameters and their ratios (Im:1), expressed through mean values (M) and coefficients of variation (Cv), the probability of a negative effect of inflammatory processes on homeostasis of UVM components (H2 O, OS, WIS) ranged from 95 % (P<0.05) to 99 % (P<0.001). Finally, results of natural mating indicated that altered color and viscosity of UVM, together with changes in the distribution of soluble and insoluble fractions of the “water–organic substances–water-insoluble substances” system, were associated with a 1.9-fold lower conception rate in the experimental group (40 %) compared with the control group (78 %).