Comparative Assessment of Oxidative and Antioxidant Parameters in Mule and Horse Neonates during Their First Month of Extrauterine Adaptation.

After parturition, a rapid transition occurs from the intrauterine to the extrauterine milieu, exposing neonates to physiological circumstances characterized by oxidative conditions that instigate the generation of reactive oxygen species. These free radicals play pivotal roles in physiological processes; however, an imbalance between their production and the removal of antioxidants can result in severe cellular damage. The main objective of this study was to compare the oxidative and antioxidant profiles in mule and horse neonates immediately post-parturition, as well as at subsequent time points (1, 6, 12, and 24 h, 7 and 30 days) during their extrauterine existence. The parameters assessed included the systemic concentrations of Thiobarbituric Acid Reactive Substances (TBARS) and carbonyl groups; the activities of the antioxidants superoxide dismutase (SOD) and glutathione peroxidase (GPx); and the levels of the total, indirect, and direct bilirubin. Our results showed no interaction effect between the neonatal groups and the assessed time points for the variables under investigation. Notably, the concentrations of TBARS, as a marker of lipid peroxidation, and bilirubin were consistently lower in the mules, whereas the glutathione peroxidase (GPx) activity exhibited higher levels in this group. The bilirubin levels were notably reduced in the mule neonates. The TBARS demonstrated a progressive decrease over the observation period in both groups, while the GPx activity remained relatively stable from birth to 7 days, with a substantial increase evident at the 30-day mark. Protein oxidation was not affected by the group and time, while for the SOD values, all times were statistically similar, except for the lower activity at T1h. Consequently, our findings lead us to the conclusion that neonatal mules and horses manifest distinct patterns of oxidative activity and antioxidant capacity during the initial month of their extrauterine existence, potentially indicative of different adaptation mechanisms to the extrauterine environment.

Evaluation of Blood Glucose and Lactate Concentrations in Mule and Equine Foals.

Information about mule physiology is scarce. Glucose and lactate serve as prognostic tools in neonates; thus, real-time evaluations would be beneficial. Our main objective was to measure glucose and lactate concentrations from healthy mule and equine foals from birth to 720 hours. Glucose and lactate concentrations were evaluated with a benchtop Randox Daytona analyzer (LAB) using plasma and with an Accutrend Plus system (ACP) using whole blood. Data were analyzed using PROC MIXED (P < .05), intraclass coefficient correlation and Bland-Altman analysis. Glucose and lactate concentrations from mule and equine foals were different when evaluated with LAB, but there was no difference when evaluated with ACP. Glucose pattern of variation, evaluated with both analyzers for mule and equine foals, had an increase, with subsequent decrease, whereas lactate pattern of variation had initial higher values with subsequent decrease. Intraclass coefficient correlation for glucose was low and moderate for lactate. Results of glucose and lactate with ACP from our experimental neonates were not highly correlated with LAB. However, the ACP had the same pattern of variation for glucose and lactate, thus can still be used clinically for immediate evaluations if the technique is standardized with the specific samples that will be used.

Effect of hCG application at different moments of the estrous cycle on corpus luteum and uterine vascularization and serum progesterone concentration in mares.

Establishment of pregnancy after embryo transfer is the ultimate goal of an embryo transfer program and increasing pregnancy rates and reducing pregnancy loss are mandatory. The utilization of treatments to improve conception rates in recipient mares has been the focus of several research groups over the last years and the results are controversial. Some studies using human chorionic gonadotrophin (hCG) found promising results. Our hypothesis was that hCG administration would cause an additional stimulation on luteal function, uterine and luteal vascularization and progesterone concentration, and the mares would have increased uterine and cervix tone. Therefore, in the present study the effects of hCG administration to induce ovulation, on day 0 (day of ovulation) or day 5 postovulation were evaluated on corpus luteum characteristics, reproductive tract vascularization, and serum progesterone concentration from ovulation until day 15 postovulation. Groups were: G1: (control) - no hCG; G2: 2500 IU of hCG to induce ovulation when a follicle greater than 35mm and uterine edema were detected; G3: 2500 IU hCG on day 0; G4: 2500 IU hCG on day 5 postovulation. Twelve mares were randomly assigned to each group, during consecutive cycles, in a Latin Square experimental design, in a total of 48 cycles. Doppler ultrasound evaluations were performed daily from day 0 until day 15 postovulation, including mesometrial vascularity, endometrial vascularity and corpus luteum vascularity. Blood samples were collected for serum progesterone concentration. Data was analyzed using the Proc Glimmix SAS Procedure for nonparametric variables and Proc Mixed for parametric parameters. There was no treatment effect for all variables studied (P > 0.05). Characteristics were only affected by day (P < 0.05). It can be concluded that hCG administration at the time points suggested in the current study did not alter the characteristics evaluated.

Follicular dynamics, ovarian vascularity and luteal development in mares with early or late postpartum ovulation.

Follicular development and deviation processes during the postpartum period are not completely known in horses. Thus, we aimed to study the characteristics of follicular dynamics and ovarian vascular perfusion during the postpartum period in mares that demonstrated estrous behavior and had early (<10 days) or late (≥10 days) postpartum ovulation. Ten mares were scanned daily by transrectal ultrasonography from the first day postpartum (d1) to the sixteenth day after the first postpartum ovulation (D0 = ovulation). The animals were split in the early (n = 3) and late (n = 7) ovulation groups (average interval between parturition and ovulation: 8.0 ± 0.0 and 14.7 ± 1.2 days, respectively). For the follicular growth, no difference (P > 0.1) was detected between the groups when the data were normalized for the days preceding the first postpartum ovulation (from D-7 to D-1). However, when the data were normalized to days postpartum, the dominant follicle was larger (P < 0.05) in the early-ovulated group in all days during this period (d1 to d7). The number of follicles >25 mm diameter was greater (P < 0.05) in the early-ovulated group during the first 3 days postpartum, and the late-ovulated mares showed greater number of follicles with 20-25 mm during d4 to d7. For blood flow characteristics, no difference (P > 0.1) was detected between groups in vascular perfusion of the dominant follicle or in the ovarian pedicle ipsilateral to the largest follicle. Similarly, no difference (P > 0.1) was detected in progesterone concentrations, corpus luteum (CL) area and vascular perfusion of the CL. Pregnancy rate did not differ (P > 0.1) between the early (3/3; 100%) and late (5/7; 71.4%) groups. Therefore, the characteristics of the follicle growth on the preceding days of ovulation were similar between the early- and late-ovulated mares and were consistent with the follicular dynamics expected in non-pregnant and non-lactating mares. However, when the data were analyzed for the days relative to parturition, greater follicle development was present in mares that ovulate earlier during the postpartum period (<10 days). The results suggest that important events may occur before parturition, resulting in early follicle development, mainly in those mares that show estrus and ovulate within 10 days postpartum.