The Interplay between Oxidative Stress and Fatty Acids Profile in Romanian Spotted Cows with Placental Retention

(1) Background: Retained fetal membranes (RFM) in cattle negatively impact reproduction, calving intervals, and health. This study examined OS markers and fatty acid profiles in Romanian Spotted cattle, comparing cows with normal parturition to those with RFM. Over 9 weeks, serum samples were collected from 22 cows (7 with RFM, 15 normal) at intervals before and after parturition. Placental tissues were also analyzed. The aim was to identify OS biomarkers that predict RFMs, track changes over time, and assess their impact on the placental fatty acid profile. (2) Methods: Samples were analyzed for superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and total antioxidant capacity (TAC). Placental fatty acids were profiled using gas chromatography-mass spectrometry. (3) Results: SOD and CAT activities increased in cows with retained fetal membranes (RFM) before parturition (SOD: <i>p</i> < 0.001, RFM 404.601 ± 20.941 vs. NP 339.101 ± 44.911; CAT: <i>p</i> < 0.01, RFM 121.132 ± 14.831 vs. NP 96.070 ± 2.397), indicating OS. However, significant decreases during labor suggested weakened antioxidant defenses. Total antioxidant capacity (TAC) peaked during parturition in RFM cows (<i>p</i> < 0.0001, 38.780 ± 3.727 vs. 11.150 ± 1.555), signaling heightened stress. Additionally, MDA levels increased before parturition (<i>p</i> < 0.001, RFM 8.424 ± 1.894 vs. NP 3.807 ± 0.484), confirming lipid peroxidation. RFM cows also exhibited higher levels of saturated fatty acids and lower monounsaturated fatty acids, pointing to metabolic stress. (4) Conclusions: This study highlights the role of OS and fatty acid imbalances in RFMs, suggesting potential strategies to improve reproductive outcomes by managing OS.