Elemental Homeostasis Factors of the Placenta Determining the Time of Placenta Separation in Cows

Disturbances of elemental homeostasis in pregnancy can negatively affect the course of labor and the postpartum period. The aim of this study is to identify the hidden factors of elemental homeostasis of the placenta that affect the time of placenta separation in cows. The experiment involves 60 pregnant Simmental cows with a singleton pregnancy, in which the time between the birth of the calf and the separation of the placenta is determined, and samples of cotyledons of the embryonic membrane are taken for analysis. The content of 27 chemical elements in the placenta samples is analyzed using inductively coupled plasma mass spectrometry. Statistical analysis is performed using the IBM SPSS Statistics 20.0 program. Levene’s test for homogeneity of variance is used and the asymmetry coefficient is calculated. Factor analysis is performed using the principal axis factorization method using Varimax rotation. The number of factors is determined based on the Kaiser and Cattell criteria. The factor values are saved by the regression method. The assumption of normal data distribution is tested using the Kolmogorov–Smirnov test with Lilliefors correction. The relationships between the established factors and the placenta separation time in cows are identified using the nonparametric two-sided Spearman rank test (rho). Six factors are formed from the indicators of the content of chemical elements in the placenta: factor 1 (Ni, B, Cu), factor 2 (Mn, Ca, Mg), factor 3 (Na), factor 4 (Se, Zn), factor 5 (Cr), and factor 6 (I). Of these, factor 3 (rho = 0.-305, p = 0.025) and factor 4 (rho = 0.316, p = 0.020) are associated with the placenta separation time. Analyzing the literature data, it can be assumed that factor 3 affects the time of placenta separation in cows through participation in the development of the placenta vascular network and factor 4 through the regulation of the state of the antioxidant system of the placenta and trophoblast growth. Disturbances in the homeostasis of Na, Se, and Zn in pregnant cows can lead to the retention of the placenta during labor.