A wide range of endocrine and haematochemical changes in the reproductive process of early pregnant mares

The aim was to compare temporarily together the changes occurred along the early pregnant and nonpregnant mares on the ovarian, adrenocortical, thyroid and haematochemical profiles (total protein, glucose, albumin, complete blood count). Sixteen mares were randomly divided into two groups: the experimental group of 10 mares submitted to artificial insemination, and the control group of six mares no submitted to insemination. The experimental group was analysed after the human chorionic gonadotropin (hCG) treatment (baseline = day 0), after the artificial insemination (T1), 24 h after (T2), 15 days after (T3) and 30 days after (T4) the insemination; the control group was analysed after placebo treatment (day 0), considering T1 the day after the placebo treatment and T2-T4 the time points after. An interaction between treatments and sampling time on estrogen (E2) (P < .0001) and progesterone (P4) (P < .0001) was observed. Compared to control group, at T4 experimental group showed higher E2 (P < .001), while P4 were lower (P < .001). A significant effect of experimental treatment over time for cortisol (P = .005) and glucose (P = .054), with the highest cortisol and glucose in the experimental mares, was observed. A significant effect of time for cortisol (P < .001), total protein (P < .01), glucose (P = .054) and white blood cell (WBC) (P < .01) was observed in the experimental group. The trend of cortisol and glucose may probably reflect the shift of energy metabolism in anabolic and/or catabolic directions along the onset of pregnancy