The effectiveness of artificial insemination begins to be determined by a series of procedures from the moment semen leaves the boar’s body. Passing quality tests in the laboratory does not mean the semen will still be in acceptable condition when it reaches the sow’s uterus; the dilution ratio, storage temperature, transport vibration, and insemination timing each affect sperm vitality and fertilization capacity. In pig farm breeding management, the management of the boar itself often receives attention, while management of the semen’s “in vitro stage” is easily treated asa technical matterIndividual operators’ habits lack standardized controls.
The first principles for handling semen after collection are speed and maintaining an equal temperature. The raw semen should undergo a quality check and initial dilution within 30 minutes of collection, and should not be left at room temperature for a long time. The diluent should be prewarmed to a temperature close to that of the semen, following the equal-temperature principle. First, perform the initial dilution at a ratio of 1∶1, then let it stand at 17℃ for 3—4 hours before carrying out subsequent dilutions. This “stepwise dilution” method is intended to allow the sperm to gradually adapt to the diluent environment and storage temperature, avoiding cold shock or osmotic damage caused by sudden changes in osmotic pressure and temperature. The effective sperm concentration after dilution should be maintained at 3.0×10⁷ to 5.0×10⁷ per milliliter, and sperm motility (tested at 37℃) should be no lower than 70%—85%. This is the baseline for ensuring conception rates.
Temperature control during storage is the second key point. Boar sperm are sensitive to low temperatures, and diluted semen is best stored in a constant-temperature environment of 16—18℃. This range can reduce sperm metabolic rates and energy consumption while avoiding cold shock and heat stress. During storage, gently mix the semen once every 12 hours to prevent sperm from settling and clumping; this is also standard practice. The effect of storage time on conception rates is supported by clear data: when insemination is performed after storage for 3—4 days, the pregnancy rate can be maintained at 85%—90%; after storage until day 5, the pregnancy rate falls to 70%—75%; by day 6, it falls further to 60%—65%. This means there is a considerable gap between “semen that can still be used” and “semen that is still worth using.” Even if semen stored beyond the recommended window still appears to have acceptable motility, its conception rate has already declined significantly. Proper semen processing can maintain sperm motility above 80%, corresponding to an increase in conception rate of 5—8 percentage points; each boar can cover 500—800 sows for breeding per year.
The final link between semen and the sow is the timing of insemination. Conventional cervical insemination relies on gravity to let semen flow naturally, and an insemination time of 5—8 minutes is recommended. Forcing the semen in too quickly increases the risk of backflow and uterine injury. Deep insemination delivers semen directly to the uterine body or the proximal uterine horn; the volume can be reduced to 35—50 milliliters, with 10—15 hundred million viable sperm, but it requires greater care when inserting the inner catheter and more operating experience. Do not force it forward if resistance is encountered. Whichever method is used, maintaining boar stimulation or applying manual pressure to the sow’s back throughout insemination, then allowing the sow to rest quietly for 5—10 minutes after insemination, helps uterine contractions transport semen toward the oviducts rather than allowing gravity to cause it to flow back out. In essence, managing semen outside the body adds a stable, repeatable “quality preservation chain” between the boar and the sow. Any lapse at any stage will become apparent weeks later in the form of return-to-estrus rates and litter size.
The first principles for handling semen after collection are speed and maintaining an equal temperature. The raw semen should undergo a quality check and initial dilution within 30 minutes of collection, and should not be left at room temperature for a long time. The diluent should be prewarmed to a temperature close to that of the semen, following the equal-temperature principle. First, perform the initial dilution at a ratio of 1∶1, then let it stand at 17℃ for 3—4 hours before carrying out subsequent dilutions. This “stepwise dilution” method is intended to allow the sperm to gradually adapt to the diluent environment and storage temperature, avoiding cold shock or osmotic damage caused by sudden changes in osmotic pressure and temperature. The effective sperm concentration after dilution should be maintained at 3.0×10⁷ to 5.0×10⁷ per milliliter, and sperm motility (tested at 37℃) should be no lower than 70%—85%. This is the baseline for ensuring conception rates.
Temperature control during storage is the second key point. Boar sperm are sensitive to low temperatures, and diluted semen is best stored in a constant-temperature environment of 16—18℃. This range can reduce sperm metabolic rates and energy consumption while avoiding cold shock and heat stress. During storage, gently mix the semen once every 12 hours to prevent sperm from settling and clumping; this is also standard practice. The effect of storage time on conception rates is supported by clear data: when insemination is performed after storage for 3—4 days, the pregnancy rate can be maintained at 85%—90%; after storage until day 5, the pregnancy rate falls to 70%—75%; by day 6, it falls further to 60%—65%. This means there is a considerable gap between “semen that can still be used” and “semen that is still worth using.” Even if semen stored beyond the recommended window still appears to have acceptable motility, its conception rate has already declined significantly. Proper semen processing can maintain sperm motility above 80%, corresponding to an increase in conception rate of 5—8 percentage points; each boar can cover 500—800 sows for breeding per year.
The final link between semen and the sow is the timing of insemination. Conventional cervical insemination relies on gravity to let semen flow naturally, and an insemination time of 5—8 minutes is recommended. Forcing the semen in too quickly increases the risk of backflow and uterine injury. Deep insemination delivers semen directly to the uterine body or the proximal uterine horn; the volume can be reduced to 35—50 milliliters, with 10—15 hundred million viable sperm, but it requires greater care when inserting the inner catheter and more operating experience. Do not force it forward if resistance is encountered. Whichever method is used, maintaining boar stimulation or applying manual pressure to the sow’s back throughout insemination, then allowing the sow to rest quietly for 5—10 minutes after insemination, helps uterine contractions transport semen toward the oviducts rather than allowing gravity to cause it to flow back out. In essence, managing semen outside the body adds a stable, repeatable “quality preservation chain” between the boar and the sow. Any lapse at any stage will become apparent weeks later in the form of return-to-estrus rates and litter size.