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Oxytocin is released from the brain of the sow at the time of mating in response to stimulation by the boar. It is assumed that it enhances sperm transport to the oviduct. Several investigators have studied whether injecting oxytocin into semen before artificial insemination improves farrowing rate and litter size. The conclusions from review of these studies are: 1) Adding 4 to 5 IU’s of oxytocin to a dose of semen improves farrowing rate and litter size; 2) Use of oxytocin-treated semen is more effective in multiparous sows than gilts; 3) During the summer months, oxytocin-treated semen significantly increased farrowing rate and litter size; and 4) In most studies, the use of oxytocin at the time of insemination was profitable. Oxytocin should be added to the semen with an insulin syringe immediately before attaching the semen vessel to the insemination catheter.