The first sexed piglets were from sows surgically inseminated with sex-sorted sperm.[6] Even with recent technological improvements in sorting efficiency, production of adequate numbers of boar sperm for uterine insemination of swine is limiting because normally 3 to 5 x 109 sperm/dose are used with the insemination being repeated two to three times during each estrus.[12] A system must be developed to deliver fewer sperm deeper into the porcine reproductive tract before sex-sorted sperm can be used effectively with AI of swine. Recently, this endoscopic approach has been replaced with a newly designed, flexible catheter for deep nonsurgical insemi-nation.[13] A 1.3-m-deep uterine insemination catheter was used to deposit 7.5 ml containing 150 x 106 unsexed sperm in the upper end of the uterine horn of sows in natural postweaning estrus. Sows inseminated one time 32 hr post onset of estrus achieved pregnancy rates of 83.3% (50/60 sows) for sexed sperm and 87.3% (48/55) unsexed sperm.[14] Adequate fertility rates were achieved with only

2 5% of the sperm used conventionally for AI in pigs. These preliminary data suggest that this approach may be suitable for efficiently producing single sex litters.

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