The use of ultrasonographic measurement of the heart size and fetal heart rate variation for gestational age determination in local Bulgarian goats.

BACKGROUND: Determination of gestational age in goats was performed using ultrasound measurements of different fetal biometric parameters. There are no data showing quadratic and exponential dependence between fetal heart parameters and gestational age. OBJECTIVES: The objective of the present study was to test the significance of the defined indicators (fetal heart rate, longitudinal and transverse fetal heart axes) for determining gestational age in local Bulgarian goats. METHODS: A total of 24 pregnant local Bulgarian goats, aged between 2 and 5 years, body weight 42-50 kg were included in the study. Ultrasonographic examinations were performed weekly on gestational days 21, 28, 35, 42 and 49. After gestational day 49 until parturition, scans were performed biweekly. The data from the measurements were subjected to linear (y = a + bx), quadratic (y = aх2 + bх + c) and exponential (y = axn ) correlation. RESULTS: Average fetal heart rate values decreased with pregnancy progression. The coefficient of determination (R2 ) and standard error of estimate (SEE) of the heart rate indicator were 0.72, 0.75, 0.58 and 15.1, 14.4, 19.2 days, respectively, for the three correlations. Longitudinal diameter (long axis) had the following values for R2 = 0.94, 0.96, 0.96 and for SEE = 7.0, 5.5, 5.5 days, for the linear, quadratic and exponential correlations, respectively, while the values of the fetal heart transverse diameter (short axis) were higher than those of the external one (R2 = 0.95, 0.97, 0.97). Simultaneously, SEE is lower (SEE = 6.1, 4.9, 5.0 days) compared to that found for the long heart fetal axis. CONCLUSIONS: For precise estimation of gestational age, use of longitudinal (long) and transverse (short) axes is recommended. Fetal heart rate is not an exact indicator but can be used as a reference for gestational age along with changes in the heart size and echogenicity.

Determination of the gestational age through ultrasound measurements of some uterine and foetal parameters in Bulgarian local goats.

The aim of the current study was to determine the gestational age in goats through the measurement of some foetal and uterine structures. Twenty-four pregnant Bulgarian local goats were submitted to ultrasound foetometry by transrectal and transabdominal approaches. Ultrasound measurement of studied parameters was done at 7-day intervals during the first trimester of gestation (days 21-49) and at 14-day intervals between gestation days 49 and 133. Associations of foetometry data with foetal age were investigated by linear (y = a + bx), quadratic (y = ax2  + bx + c) and exponential (y = axn ) equations. According to the results, some biometric parameters (uterine lumen diameter, crown-rump length, trunk diameter, biparietal diameter, foetal aortic diameter) exhibited a stronger correlation to gestational age (R2  ≥ 0.90) and lower standard error of the estimate (SEE ≤ 8) as compared to foetal eye orbit diameter, and outer and inner placentome diameters (R2  ≤ 0.90; SEE ≥ 8). Each of these biometric parameters could be measured in different periods of gestation, thus allowing for monitoring and determination of foetal age at almost all stages of pregnancy.