Masoud Saeedipanah Ardakani - DVM Graduate, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
Babak Khoramian Toosi - Department of Clinical Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
Mohammad Azizzadeh - Department of Clinical Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
Masoud Rajabioun - Department of Clinical Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran

The aim of this study was to evaluate the correlation between some fetal parameters measured by ultrasonography and fetal age for developing a formula which could be used for estimation of fetal age in Baluchi sheep. Placentome diameter (PD), gestation Sac diameter (GSD), biparietal diameter (BPD), straight crown-rump length (CRL), femural length (FL), occipito-snout diameter (OSD), thoracic diameter (TD) and fetal heart rate (FHR) were measured by transrectal and/or transabdominal ultrasonography. All ewes were synchronized using progesterone sponge for ۶ days. On the first day, they received PGF۲ and on the last day received ۴۰۰ IU of equine serum gonadotrophin (eCG). All of the parameters revealed significant correlation by increasing fetal age. Except for PD, for other values linear regression curve was illustrated. BPD (between ۳۶ - ۹۶ days) (R۲ = ۰.۹۶۱), CRL (R۲ = ۰.۹۳۵), FL (R۲ = ۰.۹۵۰), OSD (R۲ = ۰.۹۸۱), TD (R۲ = ۰.۹۷۵) showed high correlation with fetal age (p < ۰.۰۰۱). Moderate correlation was calculated for FHR (p < ۰.۰۰۱, R۲ = ۰.۸۸۳). Low correlations were assessed by measurement of GSD (p = ۰.۰۱۸, R۲ = ۰.۳۱۸), BPD (between ۹۶-۱۳۸ days; p = ۰.۰۳۸, R۲ = ۰.۲۹) and PD represented the significant non-linear correlation with age (p < ۰.۰۰۱), maximum correlation was assessed by measurement of mean placentome wall diameter. In conclusion, OSD was recommended as the best parameter for estimating of gestational age between days ۳۶ - ۱۰۹ in Baluchi sheep because of the lowest residuals, the highest correlation coefficient and wide period of availability for imaging in gestation.

Baluchi sheep, ‎ Fetal age, ‎ Ultrasonography