Prediction of gestational age by ultrasonic fetometry in llamas (Lama glama) and alpacas (Lama pacos)

Fetal biparietal diameter (BPD) and thorax height (TH) were measured by ultrasound during intrauterine growth in pregnant Ilamas (Lama glama) and alpacas (Lama paces). The goal was to establish representative curves that allows estimation of gestational age (GA) from real-time ultrasonic measurements of these fetal structures at any stage of gestation. Llamas and alpacas were mated under controlled conditions. Ultrasound exams were conducted to determine pregnancy status 1 month later. Measurements of fetal BPD and TH were conducted from the second month of pregnancy until term. Observation and assessment of fetal TH was difficult during the last 3 months of pregnancy, specially in Ilamas. Regression curves were calculated from the data as a function of GA, with the best fit represented by the following equations: Ilama GA = (BPD - 0.002399)43.02293,r = 0.98, P < 0.001; Hama GA = (TH - 0.07137)46.94485, r = 0.95, P < 0.001; alpaca GA = (BPD - 0.11376)47.23287, r = 0.98, P < 0.001; alpaca GA = (TH - 0.36436)52.87663, r = 0.96, P < 0.001, where GA was measured in days and BPD and TH in centimeters. Results indicate that ultrasonic measurement of these fetal biometric variables constitute a valuable tool to estimate GA at any stage of pregnancy in these domestic South American camelids. (C) 2001 Elsevier Science B,V. All rights reserved.