To examine the effects of maternal metabolizable protein (MP) restriction during late gestation on uterine and umbilical blood flows, conceptus size, and amino acid concentrations in the uterine and umbilical vessels, 11 ewes with singleton pregnancies were assigned to one of three isocaloric diets formulated to provide 60% of MP (MP60), 80% of MP (MP80), or 100% of MP (MP100) requirements from days 100 to 130 of gestation. On day 130 of gestation, intraoperative uterine and umbilical blood flows were obtained as well as serum samples from the uterine artery, uterine vein, umbilical artery, and umbilical vein. Ewes on the MP60 diet had lighter (P= 0.04) and smaller (P≤. 0.05) fetuses, but increased (P= 0.02) uterine blood flow relative to fetal weight compared with MP100 ewes, with MP80 being intermediate. Umbilical blood flow was similar (P= 0.70) across treatments. Glutamine, glycine, isoleucine, leucine, ornithine, serine, and valine concentrations were impacted (P≤. 0.02) by maternal treatment. While uterine flux of total serum nitrites was greater (P= 0.03) in MP60 and MP80 ewes compared with MP100 ewes, fetal flux did not differ. Decreased maternal protein intake resulted in less (P<. 0.01) maternal cytochrome P450 1A enzyme activity. There were minimal impacts of maternal diet on steroid concentrations. Maternal dietary protein may alter fetal growth by impacting placental vasculature function and nutrient absorptive capabilities.
Bibliographical noteFunding Information:
This project was supported by National Research Initiative Competitive Grant no. 2009-35206-05276 from the USDA National Institute of Food and Agriculture to K.A.V., C.S.S., and K.R.M.C. The authors would also like to thank Dr. Ron Magness for training on how to perform blood sample collection at surgery. The authors would like to thank Tammi Neville and Jim Kirsch for their assistance with the animal portion of the project.
© 2015 Elsevier B.V.
- Amino acids
- Metabolizable protein
- Umbilical blood flow
- Uterine blood flow