Location: Warmwater Aquaculture Research UnitTitle: Use of Audible and Chart-recorded Ultrasonography to Monitor Fetal Heart Rate and Uterine Blood Flow Parameters in Cattle) Author
Submitted to: Journal of Animal and Veterinary Advances
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/16/2004
Publication Date: 4/1/2004
Citation: Willard, S.T., Webb, A., Bowers, S.D., Gandy, B.S. 2004. Use of Audible and Chart-recorded Ultrasonography to Monitor Fetal Heart Rate and Uterine Blood Flow Parameters in Cattle. Journal of Animal and Veterinary Advances. 3(5):289-293. Interpretive Summary: Non-invasive means with which to monitor fetal development and viability are critical for assessing fetal health for improve production efficiency (i.e., maximizing live births, determining calving dates, etc.). Fetal aging by Doppler ultrasound may assist the producer and/or veterinary practitioner in assessing fetal age in a cost effective and efficient manner. These data establish the heart rate characteristics in relation to known fetal developmental ages to assist in the development of parameters needed to accurately determine fetal age with this technology.
Technical Abstract: The objective of the present study was to evaluate the use of audible chart-recorded doppler ultrasonography (DUS) to monitor both uterine blood flow and fetal heart rate (FHR) during pregnancy in dairy cattle. Possible applications of DUS include the monitoring of fetal distress when a pregnancy becomes compromised, or as a method for estimating fetal age through changes in FHR during gestation. In this study, 30 pregnant Holstein heifers at varying stages of pregnancy were sampled repeatedly between 54 to 262 d post-breeding. On test days, transrectal DUS (Medata Systems) was performed to quantify FHR and dam uterine artery pulse rates (UAP). Following DUS, B-mode ultrasonography was performed to obtain placentome diameter measurements as an additional measure of pregnancy stage. For the 104 total individual tests, 48 FHR, 101 UAP and 78 placentome measurements were obtained. Doppler US was also linked to a PowerLab Chart Recorder (ADI Instruments) to record FHR and UAP wave-forms for analysis. Data were analyzed using correlation and regression analysis relative to stage of gestation. Fetal heart rate was negatively correlated (R=-0.61, P<0.01) with d of gestation. Fetuses that were<140 d of age had higher (P<0.01) FHR (155.8 +/- 3.2 beats per minute; BPM) than fetuses>140 d of age (142.8 +/- 2.4 BPM). As expected, average placentome size was positively correlated (R=0.83; P<0.01) with d of gestation. However, UAP of the dam did not change (R=0.16; P>0.10) relative to d of gestation (mean: 74.1 +/- 1.0 pulses per minute). Of the 104 attempts at DUS, FHR were determined 46% of the time and UAP found 97.1% of the time. Using the PowerLab, FHR wave-forms were 808.0 +/- 13.9 mV in amplitude from baseline (62.9 +/- 5.9 mV). In contrast, UAP signatures were not different (P>0.10) from background levels (81.2 +/- 3.2 MAX mV; 44.8 +/- 3.1 MIN mV). In summary, transrectal audible DUS is effective for estimating fetal age in the bovine and can be coupled to a low-cost chart recording system for monitoring FHR characteristics.