Effects of Dietary Fatty Acids on Bovine Oocyte Competence and Granulosa Cells

Abstract

Here we assessed the effects of dietary essential fatty acids on the developmental competence of oocytes in cows and on the functionality of follicular granulosa cells (GC). Lactating German Holstein cows were supplemented from week 9 ante partum (ap) until week 8 post-partum (pp) in four dietary groups designed as (i) control (CTRL: coconut oil), (ii) essential fatty acid (EFA: linseed and safflower oil), (iii) conjugated linoleic acid (CLA: Lutalin®), and (iv) EFA+CLA (mixture of linseed oil, safflower oil and Lutalin®). EFA, CLA or EFA+CLA supplementation did not improve <i>in vitro</i> embryo production. However, higher proportions of α-linolenic acid (ALA) and <i>cis-9, trans-11</i> CLA were observed in the follicular fluid suggesting the exposure of GC to relatively high levels of ALA and <i>cis-9, trans-11</i> CLA. Consequently, we tested different concentrations of ALA and <i>cis-9, trans-11</i> CLA in a bovine GC culture model for their effects on steroid production, marker gene expression and viability. Both fatty acids upregulated <i>CD36</i> and downregulated the expression of <i>FOXL2</i>, while ALA significantly increased <i>SOX 9</i> transcript levels. Both ALA and <i>cis-9, trans-11</i> CLA reduced the <i>CCND2</i> expression and <i>cis-9, trans-11</i> CLA induced apoptosis. ALA and <i>cis-9, trans-11</i> CLA significantly down-regulated the expression of <i>STAR, CYP19A1, FSHR, LHCGR</i> and decreased the 17β-Estradiol (E2) and progesterone (P4) production. In conclusion, dietary lipids did not improve <i>in vitro</i> embryo production, while ALA and <i>cis-9, trans-11</i> CLA affected the morphology and functionality of GC. This could suggestively lead to compromised follicle development and ovarian cyclicity in dairy cows.