Abstract #W248

# W248
Effects of realimentation on umbilical blood flow, fetal and placental measurements, and birth weight in nutrient-restricted pregnant ewes.
Manuel Vasquez*1, Kendall Swanson1, Kimberley Vonnahme1, 1North Dakota State University, Fargo, ND.

Nutritional restriction (60% of total nutritional requirement) from d 50 to 130 applied in nulliparous ewes has shown to reduce umbilical blood flow (UBF; Lemley et al., 2012; AJP 302:R454-R467). We hypothesized that during restriction, UBF and fetal and placentome measurements would be less than in adequately fed ewes, but upon realimentation, ewes would have similar UBF as ewes that were never restricted. Second parity Dorset ewes were assigned either to an adequate nutrition group (CON, n = 7) or a restricted (60% of CON) group (RES, n = 8), from d 50 to 90 of gestation. On d 90, all ewes were fed 100% of nutritional requirements according to body weight. Ewe body weight and conceptus measurements via ultrasonography were recorded every 10 d from d 50 to 130 of gestation. Every 10 d, length and width from 10 random placentomes were averaged and then multiplied to obtain placentome area. Fetal biparietal and abdominal lengths were recorded. Doppler mode was used to obtain UBF, pulsatility index (PI), and resistance index (RI). At birth, lambs and placental measurements were obtained. The data were analyzed using the Proc Mixed procedure of SAS. Treatment and day were treated as fixed effects, ewe as random. By d 70, RES ewes were lighter (P < 0.01), and remained lighter than CON ewes throughout the experiment. While there were no treatment by day interactions or main effects of treatment (P > 0.13) for any measurements obtained by ultrasonography, there were some interesting observations. On d 80, UBF and placentome area were decreased, and PI, RI, and biparietal distance increased in RES vs CON ewes (P ≤ 0.05; means separation of unprotected F test). On d 90, before the realimentation, all ultrasound measurements were similar. After realimentation, there was no effect of treatment on any of the ultrasound measurements. At birth, lambs and placental measurements were similar (P > 0.43). Perhaps the increased resistance indices and smaller placentome size on d 80 were a trigger to the dam to enhance UBF to the growing fetus. Further studies are needed to determine the impact of maternal age and parity in the face of nutrient restriction on UBF.

Key Words: ewe, pregnancy, blood flow