126 Uncovering the metabolomic fingerprint of metritis in dairy buffalo: preliminary results

Metritis is a uterine pathology typical of the early postpartum that causes economic losses in dairy farming owing to reduced milk production and reproductive efficiency and increased veterinary costs. This work aimed to evaluate variations in serum metabolites associated with postpartum metritis in dairy buffaloes. For this purpose, in this preliminary study, blood samples were collected from the lateral tail vein during routine veterinary visits at 10 ± 2 days after calving in a buffalo farm in Campania region (Italy) during the January–May period. Animals were classified according to clinical presentation as previously described (Sheldon et al. 2006 Theriogenology 65, 1516–1530) and divided into healthy (CTRL) and metritic (M) groups. Briefly, animals with a delay in uterine involution associated with a fetid watery content of red-brown color and with an increase in body temperature (>39.5°C) were included in the M group, while animals showing no delay in uterine involution, without pathologic content or any sign of systemic disease, were classified as the CTRL group. Body condition score (BCS) was assessed on a 1- to 9-point scale in all animals. The analysis excluded animals with previously reported reproductive pathologies and those diagnosed or medically treated for any other condition in the last 3 months. Among all visited animals, 10 animals homogeneous by age and parity were selected per group. Metabolites from serum samples were extracted with methanol and directly analyzed by liquid chromatography–mass spectrometry. Raw data were preprocessed and subjected to statistical analysis, namely Principal Component Analysis (PCA) and Student t-test (P < 0.05; fold change > 2.0). Significant metabolites were putatively identified by comparison of monoisotopical masses with those collected in an in-house database. The BCS was similar in CTRL and M groups (mean ± SD: 6.9 ± 0.6 and 7.0 ± 0.4, respectively). The PCA showed a clear separation between CTRL and M buffaloes, indicating differences in the serum metabolomic fingerprint between healthy and metritic animals. Univariate statistical analysis demonstrated a significant difference in the abundance of 72 metabolites between the two groups, with 58 metabolites less abundant and only 14 more abundant in the M group compared with CTRL. Among these, three metabolites were putatively identified: 7-ketodeoxycholic acid, clupanodonic acid, and Nα-acetyl-l-arginine. Particularly interesting was the finding in CTRL of higher levels of Nα-acetyl-l-arginine, which is known to be involved in the regulation of inflammation. In conclusion, these preliminary results underline how the study of the metabolomic profile may be helpful to the veterinary practice and the health management of the herd. Further studies are, however, necessary to identify other metabolites involved in the process. Moreover, the identification of serum metabolome variations before the development of the pathology, as well as the metabolic pathways affected, will allow the identification of reliable risk markers of metritis in buffalo and develop corrective targeted therapies.