Maternal nutrition affects the composition of follicular fluid and transcript content in gilt oocytes

Metabolomics focused on reproduction have been the subject of special interest in the past decade. Metabolite profiling provides detailed information on the status of follicular fluid and follicular cells which accompany the growing oocyte. Although nutrients present in the diet reach oocytes via the follicular fluid, it is not evident whether oocyte/embryo quality can be predicted based on the follicular fluid composition. Since this phenomenon has not yet been investigated in the pig, the aim of the present study was to investigate associations between diet composition and (1) selected markers related to developmental potential of oocytes (brilliant cresyl blue - BCB test, relative transcript abundance of EEF1A1 and ATP5A1 marker genes) and (2) fatty acid profile in the follicular fluid. Gilts were fed control and experimental diets which differed in composition and fatty acid profiles. The experimental diet used in this study comprised mainly locally grown grains (barley and rye) traditionally used for fattening pigs in Poland. Cumulus-oocyte complexes were aspirated from individual pairs of ovaries after animal slaughter, evaluated morphologically and subjected to the BCB test. Relative transcript abundance for the two marker genes was monitored by real-time PCR in oocytes of both categories (BCB+ and BCB-). Fatty acid profile in follicular fluid was analyzed by gas chromatography. We show that the experimental diet rich in n-3 fatty acid significantly influences fatty acid composition of the follicular fluid. The fatty acid profile of the follicular fluid of gilts fed the experimental diet differed from that of the control females. The content of saturated fatty acids was higher in the experimental group, whereas unsaturated and polyunsaturated fatty acids were more abundant in the control group (P < 0.05). With regard to individual fatty acids, only C16:0 (palmitic acid), C18:2n-6 (linoleic acid) and C22:6 (docosahexaenoic acid) differed significantly. The abundance of ATP5A1 mRNA was influenced neither by diet composition nor by oocyte category (BCB+/BCB-) whereas that of the EEF1A1 was affected by both factors. Since higher mRNA level of the EEF1A1 gene was noted in BCB+ oocytes this may be considered as a marker of oocyte quality in the pig.