Abstract
Our main objective was to compare the composition of the oviductal fluid (OFL) between cows of high and low receptivity to the embryo. A model for receptivity based on the manipulation of the size of the preovulatory follicle (POF) was used to compare the composition of the OFL. Using this model, it has been proved that the oviduct of high receptivity cows has differences in morphology, gene expression, and extracellular matrix remodeling when compared to low receptivity cows. Cycling, non-lactating, multiparous Nelore cows (n = 14) were presynchronized before receiving cloprostenol (large follicle [LF] group) or not (small follicle [SF] group), along with a progesterone (P4) device on Day (D) ─10. Devices were withdrawn, and cloprostenol administered 42–60 h (LF) or 30–36 h (SF) before GnRH agonist treatment (D0). As a result, higher estrogen concentrations, corpora lutea, and progesterone concentrations were also observed in the LF group in comparison to the SF group. Four days after GnRH-induced ovulation, OFL was collected. Quantitative mass spectrometry was used to determine the concentration of 21 amino acids, 21 biogenic amines, 40 acylcarnitines, 76 phosphatidylcholines, 14 lysophosphatidylcholines, 15 sphingomyelins, 29 hexoses, and 17 prostaglandins and related compounds in the OF. MetaboAnalyst 3.0 was used to identify which metabolites better explained the separation of experimental groups and which could potentially be used as markers of receptivity. After multivariate and PLS analysis, samples of the LF and SF were divided clearly into two non-overlapping clusters. The most influential variables to separate the two groups included: Glutamate, Leucine, four phosphatidylcholines, three lysophosphatidylcholines, and arachidonic acid. Univariate analyses further confirmed these results. There were statistical differences in the concentration of 31 metabolites (P ≤ 0.05) between groups. We concluded that the composition of the OFL is different between cows with contrasting receptivity and fertility status.