The Thai Journal of Veterinary Medicine


The objective of this review is to update information concerning the function of seminal plasma on the pig reproductive system, as well as its importance in artificial insemination (AI). It has been shown that seminal plasma advances ovulation in gilts by an average time of 10-14 hours, improves sperm motility, sustaines sperm viability during uterine transport, suppresses immune activities (chemotaxis of neutrophils), improved sperm transport, improves fertilisation rate, improves litter size in gilts and indirectly enhances fertility. The hormone estrogen, within the seminal plasma, causes a release of prostaglandins from the pigs endometrium to the utero-ovarian veins and lymphatic vessels. Therefore, it seems that the effect of seminal plasma constituents (both the oestrogen and the protein fraction) on ovulation is due to a local mechanism and not a systemic one. The swine industry’s routine procedure for extending semen is based on standardised sperm numbers. Optimising both sperm number (3 x 109 motile sperm) and seminal plasma (8-12% by volume) in AI doses could well improve pig fertility.

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