Abstract

This study aimed to establish precise gestational age estimation and evaluate the applicability of prenatal fetal sex determination in Arabian horses, a breed for which existing regression models may be inadequate due to their smaller, refined conformation.Seven maiden Arabian mares were inseminated, and transrectal ultrasonography was performed daily from ovulation to day 35, then weekly until day 91, and biweekly until parturition to monitor embryonic and fetal development.Parameters measured included embryonic vesicle (EV), crown-rump length (CRL), biparietal diameter (BIP), stomach diameter (STD), chest depth (CHD), abdominal diameter (ABD), kidney length (KDL), eyeball diameter (EBD), and eye lens length (ELL).The EV was first detected on day 10.3 ± 0.5, the embryo proper on day 21.3 ± 1.3, organization on day 33.6 ± 2.0, and ossification on day 57.7 ± 3.5 of gestation.All parameters except CRL, ELL, and KDL showed linear growth, with strong correlations with gestational age (p < 0.0001).Fetal sex was determined between days 56 and 161, with optimal accuracy between days 105 and 133, achieving 64.9% applicability and 98% accuracy.These findings provide a chronological reference for fetal development and sex determination in Arabian horses, supporting more precise breeding management in this breed. Changing patterns of infertility in female dromedary camels in Saudi Arabia: A clinical survey of 633 cases Verändernde Muster der Unfruchtbarkeit bei weiblichen Dromedarkamelen in Saudi-Arabien: Eine klinische Untersuchung von 633 Fällen