Effect of Peri-Uterine Fat Deposition on Placental Efficiency and Pregnancy Indicators at Different Gestational Stages in Arabi Ewes Using Ultrasonography

Abstract

This study was conducted to evaluate the effect of age and gestational stage on reproductive adipose tissue deposition and its relationship with placental efficiency and some pregnancy indicators in Arabi ewes, as well as to assess the feasibility of using transabdominal ultrasonography as a non-invasive method for estimating reproductive adipose tissue. The study was carried out on 27 Arabi ewes distributed across three age groups (1.5, 2.5, and >3.5 years) during the three gestational stages. The results revealed a significant increase (P ≤ 0.05) in uterine weight, reproductive adipose tissue weight (peri-uterine and peri-ovarian), placental weight, and fetal weight with advancing age and gestational stage, with the highest values recorded in the oldest ewes during the third gestational stage. Despite the significant decrease in cotyledonary number with advancing age and gestational stage, the total placental surface area increased significantly, indicating a functional compensatory mechanism that contributes to maintaining maternal-fetal exchange efficiency. The results also showed that placental efficiency increased with advancing gestational stage, while it decreased with increasing ewe age, with the highest values recorded in the 1.5-year-old age group. The interaction between age and gestational stage had a significant effect on reproductive adipose tissue deposition, with percentages ranging from 0.76% to 1.12% of carcass weight, corresponding to 140.7–247.4 grams. Ewes older than 3.5 years during the third gestational stage achieved normal pregnancy with normal fetal weights (3633.7 g), without any signs of ovarian cysts or hormonal disorders. Transabdominal ultrasonography demonstrated the feasibility of evaluating reproductive adipose tissue area surrounding the uterus and ovaries during early and mid-pregnancy, with clear variation according to ewe age and gestational stage. Post-slaughter anatomical measurements were consistent with ultrasonographic estimates, supporting the potential use of ultrasonography as a non-invasive tool for assessing reproductive adipose tissue deposition in Arabi ewes. The evaluation did not include the late gestational stage due to the fetus occupying most of the uterine cavity, which limited the clarity of the surrounding reproductive tissues valuation during late gestation was not feasible because the fetus occupied most of the uterine cavity, limiting visualization of the surrounding reproductive tissu These findings i valuation during late gestation was not feasible because the fetus occupied most of the uterine cavity, limiting visualization of the surrounding reproductive tissu ndicate the pivotal role of reproductive adipose tissue as a structural and metabolic support for the uterus, contributing to placental development (placentogenesis) and fetal growth. Furthermore, ultrasonographic assessment of reproductive adipose tissue represents a promising biomarker for monitoring pregnancy competence and placental development in Arabi ewes. This parameter may therefore be incorporated into reproductive management programs to improve reproductive efficiency and flock productivity in sheep.