ESTIMATION OF FOETAL AGE USING ULTRASONOGRAPHIC BIOMETRIC PARAMETERS IN RABBITS

Abstract

Accurate estimation of foetal age in rabbits is essential for effective reproductive management, research planning, and timely clinical intervention. This study evaluated the use of ultrasonography measurements of key foetal parameters to predict gestational age in New Zealand White rabbit Does. Eight adult virgin Does were naturally mated individually using eight bucks, and scanned using a Medison S600V ultrasound machine equipped with a 6.5 MHz transcutaneous curvilinear probe. Ultrasonographic examinations were performed on days 4, 8, 12, 16, 20, 24, and 28 post-coitus. Crown-rump length (CRL), biparietal diameter (BPD), and embryonic vesicle (EV) diameters were recorded and analyzed. All parameters showed progressive increases with advancing gestation: CRL increased from 0.5 cm (day 8) to 4.5 cm (day 28); BPD from 0.4 cm (day 12) to 1.7 cm (day 28); and EV diameter from 0.39 cm (day 4) to 2.8 cm (day 24). Strong positive correlations were observed between gestational age and CRL (R = 0.991), BPD (R = 0.995), and EV (R = 0.994). The derived regression models GA = 4.840(CRL) + 7.027; GA = 12(BPD) + 8; GA = 7.753(EV) + 0.999 demonstrate high predictive value and statistical significance (p≤0.01). These findings confirm that CRL, BPD, and EV are reliable biometric indicators for estimating foetal age in rabbits. The study provides practical reference data that can enhance reproductive monitoring, improve timing of interventions, and support biomedical research involving rabbit gestation.