Seasonal Reproductive Patterns, Estrus Behavior, and Ovarian Dynamics in Arabian Mares

Abstract

Seasonality is a major determinant of reproductive efficiency in mares and can complicate breeding management during transitional periods. This study characterized seasonal reproductive patterns, estrus behavior, and ovarian dynamics in Arabian mares maintained under natural photoperiod in Baghdad, Iraq. Ten clinically healthy mares (5-15 years; 9 ± 3 years) were monitored for 12 months. Estrus was detected by daily teasing and recorded using a standardized semi‑quantitative scoring system. Rectal examination and transrectal ultrasonography (7.5 MHz) were performed at 15‑day intervals (10‑day intervals in irregular/prolonged estrus) to evaluate ovarian activity and confirm ovulation. Mares were classified as true polyestrus (Group A, n=6) or seasonal polyestrus (Group B, n=4) according to winter ovarian activity. Group B mares exhibited spring transition (March-May), a summer breeding season (June-August), autumn transition (September-November), and deep winter anestrus (December-February). Estrus intensity varied among individuals but generally escalated to peak receptivity (+++). Preovulatory follicles typically reached approximately 3-4 cm, and ovulation occurred 24-48 hr before the end of the follicular phase (estrus). Ovulation occurred slightly more frequently from the left ovary (53.6%) than the right (46.4%). These benchmarks provide practical field indicators for reproductive management of Arabian mares under Iraqi conditions. Download Full Text