As a one of unsaturated fatty acid, polyunsaturated fatty acids (PUFAs) have multiple actions: as precursor of prostaglandins (PGs), steroid hormone synthesis and energy production in animal reproduction. PUFAs, which include omega-3 (n-3) and omega-6 (n-6), are derived from the diet and changed by diet, species, breed and season. The plasma membrane of spermatozoa in mammals contain various PUFAs. These composition of PUFAs regulate the membrane fluidity and cause lipid peroxidation via generation of reactive oxygen species (ROS). Induced lipid peroxidation by ROS decreased viability and motility of spermatozoa, and it is reduced by addition of antioxidant and low concentration of PUFAs. Because oocytes of animal have a high lipid components, process of oocyte maturation and embryo development are influenced by PUFAs. In in vitro study, oocyte maturation, embryo development, intracellular cAMP and MAPK activity were increased by treatment of n-3 α-linolenic acid (ALA) during maturation, whereas n-6 linoleic acid (LA) negatively influenced. Also, inhibition of fatty acid metabolism in oocyte influenced blastocyst formation of cattle. PGs are synthesized from PUFAs and various PUFAs influence PGs via regulation of PG-endoperoxide synthase (PTGS). Steroid hormone synthesis from cholesterol is regulated by expression of steroid acute regulator (StAR) protein and mRNA. Exogenous n-3 and n-6 PUFAs altered sex hormone in animal through stimulate or inhibit StAR activity. Because PUFAs altered PG and steroid hormone synthesis, follicular development was influenced by PUFAs. This effect of unsaturated fatty acid could provide information for improvement of reproductive ability in animals.

The objective of this study was to examine the effect of caffeine and sodium bicarbonate in a fertilization medium on the fertilizability of boar spermatozoa that were frozen in straws. Boar spermatozoa were extended with Beltsville F5 extender and frozen in 0.25‐ml straws. In vitro matured porcine oocytes were fertilized in vitro (IVF) with frozen‐thawed boar spermatozoa for 6 h in a modified tris‐buffered medium (mTBM) or in its modified medium by substituting the tris with 25 mM sodium bicarbonate (modified bicarbonate‐buffered medium; mBBM). Some of inseminated oocytes were fixed and stained for examination of sperm penetration. IVF embryos were cultured in a North Carolina State University‐23 medium for embryo development. The percentage of live sperm was 47±4% and morphological abnormality of acrosome was found in 14±3% of spermatozoa. Optimal sperm concentration for IVF was 0.75～1.0×106 sperms/ml when mTBM containing 5 mM caffeine was used as the fertilization medium. Sperm penetration was significantly (p<0.05) stimulated by increasing caffeine concentration in the IVF medium. In addition, mBBM significantly (p<0.05) increased sperm penetration (92%) compared to mTBM (65%). More (p<0.05) blastocysts (22% vs. 32%) developed from the oocytes that were fertilized in mBBM containing 1 mM caffeine than from those fertilized in mTBM with 5 mM caffeine. Our results indicate that boar spermatozoa can be frozen successfully in straws with holding their normal fertilizability and that caffeine and sodium bicarbonate stimulates sperm penetration in vitro.