Authors : S. Bowers, S. Gandy , K. Graves , A. Moore and S. Willard
Abstract: The objective of this study was to determine whether relative changes in vaginal electrical impedance (VEI) readings would correlate to characteristics associated with involution of the uterus and hormone profiles postpartum in the dairy cow. In experiment I, the use of VEI measurements for monitoring follicular development and ovulation were verified. Jersey cows (n = 16) were administered prostaglandin F2a (PG) and sampled at 12 h intervals for 7 d post-PG. At each sampling period, VEI measurements were recorded, ultrasonography was performed to obtain follicular measurements, and serum samples collected for the determination of progesterone (P4) and estradiol (E2) using RIA. Serum concentrations of P4 decreased and E2 increased post-PG, while VEI decreased prior to ovulation; which is consistent with previous studies. In experiment II, Jersey cows (n = 18) were sampled twice weekly from d 1 to 60 postpartum (PP). On these days, VEI measurements were recorded, follicular sizes and cross-sectional area of the left and right uterine horns captured using ultrasonography, uterine tone scores assigned by palpation and serum samples collected for P4 and E2 determinations. Uterine horn diameter differences were negatively correlated with uterine tone scores and VEI measurements (i.e., as uterine horn diameter differences decreased, uterine tone and VEI measurements increased). Uterine tone scores were also positively correlated with VEI measurements. The relationship of VEI to early PP uterine involution was further confirmed in Holstein cows (n = 25), with increases in VEI readings occurring from week 2 to week 4 PP. In summary, VEI measurements patterned periovulatory hormonal profiles for cycling Jersey cows, and were significantly correlated with changes in uterine size, uterine tone, resumption of estrous cycles and/or day PP in Jersey and Holstein cows post-calving. These data suggest that VEI may be used as an objective tool for quantifying the association of uterine involution with the resumption of reproductive cyclicity (as determined by P4 and E2 profiles) in the PP dairy cow.
Bowers, S. , S. Gandy , K. Graves , A. Moore and S. Willard , 2006. Relationships Between Measurements of Vaginal Electrical Impedance, Uterine Involution and Hormonal Profiles in Postpartum Dairy Cows. Journal of Animal and Veterinary Advances, 5: 552-558.