Differences in mean grey levels of uterine ultrasonographic images between non-pregnant and pregnant ewes may serve as a tool for early pregnancy diagnosis.

The aim of this study was to determine how physiological and hormonal changes in the uterus during the estrous cycle and early gestational period affect the average grey values of pixels when conducting computer-assisted analysis of uterine ultrasonic images in ewes. For this purpose, 60 ewes on which there had been an estrous synchrony regimen imposed were included in the study. Animals were assigned to two groups with ewes not being mated and assessments occurred during the subsequent estrous cycle (Group 1; n = 25) and ewes being mated and assessments occurring during the subsequent early gestational period (Group 2; n = 35). Ewes were examined utilizing real time ultrasonic procedures and uterine images were obtained. Digital analysis of uterine ultrasonographic images was performed using image J program and mean grey levels (MGL) were determined. Values for progesterone concentrations were consistent with those previously reported in non-pregnant and pregnant ewes. There was a close association between MGL values in ewes of both Group I (P < 0.05) and II (P < 0.05) and days of the estrous cycle. There was also an association between MGL values and day of the gestational period in ewes of Group 2(P < 0.001). In conclusion, there are differences in MGL values between non-pregnant and pregnant ewes with there being changes as days of the estrous cycle and day of gestation period advances, therefore, this procedure could be used as a pregnancy diagnostic criterion during the early period of gestation in ewes.