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Efficacy of Using Vaginal Conductivity as an Indicator of the Optimum Time to Breed in Swine^1,2,

Clemson University^,4, Clemson, SC 29631

Abstract

Two experiments were conducted to test the efficacy of using vaginal conductivity measurements to predict ovulation time in swine. In Exp. 1, 10 normally cycling 6-mo-old purebred Hampshire gilts were tested daily through two estrous cycles in order to characterize conductivity patterns. In all females, onset of behavioral estrus was verified by daily observation in the presence of a sexually active boar. Significant changes in vaginal conductivity by day of the cycle were detected in all females tested, with a high degree of variation among individuals. A 10% increase in conductivity occurred 12 to 24 h after the onset of estrus, which is coincident with the time normally associated with high fertility. In Exp. 2, 46 prepubertal crossbred and purebred Yorkshire gilts and 17 multiparous purebred Yorkshire and Duroc sows were assigned randomly to eight treatment groups. All females were checked twice daily for the onset of estrus and vaginal conductivity readings were taken from approximately 3 d before estrus until breeding. Females were bred by artificial insemination or handmated at times determined either by detection of estrus alone or when a 10% increase in conductivity readings occurred relative to the onset of estrus. Similar conception rates were achieved in animals bred after a 10% change in vaginal conductivity as compared with detection of estrus. These results indicate that vaginal conductivity measurements during estrus provided a reliable basis for determining the time to breed swine. However, there was no advantage associated with the use of vaginal conductivity.

¹ Contribution No. 2182, Clemson Univ. Agr. Exp. Sta., Clemson, SC 29631.

² This project was supported in part by BRSG S07RR07180 awarded by the Biomedical Research Resources, National Institute of Health.

³ The authors express appreciation to Peter Burrows and Hoke Hill for assistance with data analysis; Joe Burkett, Jesse Eargle, Vernon Richey and Arnie Welmaker for invaluable technical help and animal care.

⁴ Dept. of Anim. Sci.