Characterization of the Reproductive Tract in Recipients for Bovine Embryo Transfer: pH and Bacterial Presence

Pregnancy rates of bovine recipients following embryo transfer are key factors in profitability and genetic gains. The uterus is a dynamic organ that is essential for pregnancy; however, no selection criterion for recipient uterine environment exists. At transfer, pH and temperature of the ipsilateral uterine horn at site of embryo deposit and vagina were recorded in experiment one (n = 120). Vaginal pH and ipsilateral horn pH were correlated (r=0.72, P <0.0001). Vaginal and ipsilateral pH and temperature did not differ between pregnant and non-pregnant animals in experiment one. Measuring uterine environment decreased pregnancy rates (27 versus 55%, P = 0.03; pregnant versus non-pregnant, respectively). In experiment two, abattoir collected reproductive tracts (n = 43) revealed a correlation between ipsilateral uterine horn and vagina pH (r = 0.59, P < 0.0001) and temperature (r = 0.81, P < 0.0001) utilizing the field probe. Logistic regression models in experiment three recipient animals (n = 136, vaginal pH and temperature with field probe) predicted pregnancy likelihood based on vaginal pH (P = 0.15), vaginal temperature (P = 0.3), and rectal temperature (P = 0.15). Groups based on these models revealed no impact of vaginal pH (P = 0.42) or rectal temperature groups on pregnancy rates (P = 0.83 and 0.59, respectively). Chapter 3 utilized abattoir bovine reproductive tracts (n = 43) with an approximate day 7 corpus luteum for analysis of bacteria presence on uterine and vaginal pH. Anaerobic presence impacted pH in ANOVA and regression models (P = 0.05 and P = 0.02, respectively). Bacterial presence in the ipsilateral horn did not affect ipsilateral pH, and vaginal bacterial growth did not predict ipsilateral horn environment. Thus, vaginal pH was highly correlated to ipsilateral horn pH. Presence of bacteria at site of embryo deposit did not impact ipsilateral horn pH.