Evaluation of transrectal real-time ultrasound for use in identifying sources of reproductive failure in weaned sows

Abstract

Real-time ultrasound (RTU) may aid in identifying sources of reproductive failure. In the month prior to observation, a commercial 2500-sow unit experienced an increase in the wean-to-estrus interval and reduced conception rates. A subpopulation of 52 sows was examined using RTU once daily on days 4, 5, and 6 postweaning. Transrectal RTU of the ovaries and uterus, performed following estrus detection, required 3.5 minutes per sow. To identify sources of reproductive failure, measures of follicle size, cysts, and time of ovulation were analyzed with sow records. Only 38 of the 52 sows expressed estrus within 7 days of weaning (73%), and only 29 sows ovulated (56%). Nine of the 23 sows that failed to ovulate (24%) were detected standing. Cystic ovaries were observed in four sows that failed to ovulate (17%) and in two sows that ovulated (7%). Of the 14 sows not detected in estrus, none ovulated (0%). The average estrus-to-ovulation interval, which was 39 hours, was influenced by the wean-to-estrus interval. Characterization of the reproductive tract may be used to evaluate the adequacy of estrus detection and artificial insemination procedures and the incidence of pathological conditions.