The effect of maternal nutritional status during mid-gestation on placental characteristics in ewes

The aim of this study was to determine the effects of maternal nutritional status during mid-gestation on placental characteristics in ewes. Time of estrus of 3-5 years old Karayaka breed ewes was synchronized and mating was monitored to determine the day 0 of gestation. The ewes had similar body weights (47.8±0.7kg) and loin eye muscle values (thickness; 20.9±1.0mm and fat thickness; 4.7±0.5mm) at mating. The ewes were allocated into two treatment groups at day 30 of gestation; under-fed (UF; n=12) and well-fed (WF; n=13) groups. The ewes in UF group were fed with a diet to provide 50% of their daily requirement from day 30 to day 80 of gestation and 100% of their daily requirement during the rest of the gestation period. The ewes in WF group were fed at least 100% of their daily requirement throughout gestation. The singleton bearing ewes in the UF group had a lesser (P<0.05) placental weight (354.1 compared with 378.3g), average cotyledon weight (1.50 compared with 1.82g) and lamb birth weight (3.8 compared with 4.2kg) than singleton bearing ewes in the WF group. There were positive correlations between placental weight and lamb birth weight (r=.469; P<0.05), placental weight and average cotyledon weight (r=.695; P<0.01), average cotyledon weight and lamb birth weight (r=.742; P<0.01) and placental efficiency and cotyledon density (r=.853; P<0.01) for ewes in WF group. Additionally, the pattern of weight gain/loss was different (P<0.05) between the two groups. Ewes in UF group lost body weight progressively from day 30 of gestation until day 80. The results of present study show that under-feeding of ewes during mid-gestation may cause an insufficient placental development and hence alter fetal development resulting in a reduced birth weight from singleton pregnancies.