Polyunsaturated fatty acids and fertility in female mammals: an update.
2013
Wathes, D. C. | Cheng ZhangRui | Marei, W. | Fouladi-Nashta, A.
Both <i>n</i>-3 and <i>n</i>-6 polyunsaturated fatty acids (PUFAs) are derived from the diet, with concentrations in the reproductive tract reflecting dietary intake. PUFAs have multiple functions: as precursors to eicosanoids, regulators of steroid biosynthesis, inflammatory mediators and supplying energy (particularly in oocytes). The PUFA composition of cell membranes affects signalling pathways and susceptibility to oxidative damage. All of these roles may influence reproduction although results are often inconsistent between studies. Supplementation of cows with various PUFAs can increase the numbers of antral follicles although work on polyovular species (pigs, rodents) has usually failed to detect a change in ovulation rate. The anti-inflammatory actions of <i>n</i>-3 PUFAs may reduce follicular PGE production, delaying ovulation and allowing ovulatory follicles to grow larger and produce more steroid. Various PUFA supplements can reduce the interval from calving until first ovulation in cattle although the mechanism is uncertain. Both <i>n</i>-3 and <i>n</i>-6 PUFA supplements have been fed to various species before collecting oocytes for <i>in vitro</i> fertilization. Positive, negative and no effects on subsequent embryo development have all been reported. When PUFAs are added directly to oocyte maturation medium, high doses of linoleic acid (18:2 <i>n</i>-6) are consistently deleterious, while alpha-linolenic acid (18:3<i>n</i>-3) has been associated with positive outcomes. Uterine prostaglandin production regulates luteal regression and pregnancy recognition. Supplementary <i>n</i>-3 PUFAs have either increased or decreased PGF<sub>2alpha</sub> production in different studies. There is some evidence that cattle and pigs fed a PUFA supplement post insemination may have an increased pregnancy rate.
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