Pregnancy diagnosis in sows: a comparison of the vaginal biopsy and Doppler ultrasound techniques

Two pregnancy diagnosis techniques, vaginal biopsy and ultrasonic detection, were applied to 190 sows following service. Of 172 sows diagnosed pregnant by vaginal biopsy, five did not farrow. Of 18 sows judged not pregnant, one produced a litter. With the ultrasound technique, 175 sows were diagnosed pregnant, but 11 did not farrow. Of the remaining 15 sows considered not pregnant by the 39th day after service, four farrowed. The biopsy result was usually available up to 48 hours earlier than the ultrasound result. It was concluded that where laboratory facilities are available, the biopsy technique is the method of choice.