Factors Contributing to Embryonic Mortality in Mares Within the Tiaret Region, Algeria

Abstract

Embryonic mortality in mares is of significant importance as it directly impacts reproductive efficiency in equine breeding programs. Elevated embryonic mortality rates result in reduced pregnancy success, extended breeding cycles, and significant economic setbacks for breeders and those involved in the equine industry.  In this paper, our aim is to elucidate the diverse factors associated with embryonic mortality in mares at the National Stud of Chaouchaoua, Stud El-Mesk, and mares owned by a private farm in the Tiaret region, west of Algeria. We have validated our experimentation through ultrasound-based pregnancy monitoring, aconducted on a sample of 197 mares representing diverse breeds: 125 Arabians, 26 Barbs, 21 Arabian-Barbs, 18 Thoroughbreds, 4 Anglo-Arabians, and 3 saddle mares. The monitoring was initiated on the 13th day following ovulation within the breeding season. Based on our findings, the embryonic mortality rate within the initial 45 days post-ovulation stood at 14.3%. Among these, 5.5% of embryonic mortalities were identified between D 13 and D 20 following ovulation. The incidence of embryonic mortality was notably elevated in barren mares at 22.8%, mares aged over 16 years at 15%, and those bred at the onset of the season (February) at a staggering 50%. Additionally, mares with twin pregnancies exhibited a heightened embryonic mortality rate, accounting for 75% of cases in contrast to the 11% observed in single-pregnant mares. An alteration in the uterine environment also contributed to diminished fertility, leading to a substantial embryonic mortality rate of 22.4%, attributable to irregular uterine fluids. The significant influence of variables like embryonic vesicle count, reproductive status, and abnormal uterine environment on embryonic development highlights the importance of understanding and acknowledging these factors. This knowledge is essential for reducing losses in equine farming.