Effect of Variable Long-Term Maternal Feed Allowance on the Development of the Ovine Placenta and Fetus

Quigley, S.P.; Kleemann, D.O.; Walker, S.K.; Speck, P.A.; Rudiger, S.R.; Nattrass, G.S.; DeBlasio, M.J.; Owens, J.A.

doi:10.1016/j.placenta.2008.02.014

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Volume 29, Issue 6 , Pages 539-548, June 2008

Effect of Variable Long-Term Maternal Feed Allowance on the Development of the Ovine Placenta and Fetus

S.P. Quigley
- South Australian Research and Development Institute, Turretfield Research Centre, Rosedale, SA 5350, Australia
- South Australian Research and Development Institute, Livestock Systems Alliance, Roseworthy Campus, University of Adelaide, Roseworthy, SA 5371, Australia
D.O. Kleemann
- South Australian Research and Development Institute, Turretfield Research Centre, Rosedale, SA 5350, Australia
S.K. Walker
- South Australian Research and Development Institute, Turretfield Research Centre, Rosedale, SA 5350, Australia
P.A. Speck
- South Australian Research and Development Institute, Livestock Systems Alliance, Roseworthy Campus, University of Adelaide, Roseworthy, SA 5371, Australia
S.R. Rudiger
- South Australian Research and Development Institute, Livestock Systems Alliance, Roseworthy Campus, University of Adelaide, Roseworthy, SA 5371, Australia
G.S. Nattrass
- South Australian Research and Development Institute, Livestock Systems Alliance, Roseworthy Campus, University of Adelaide, Roseworthy, SA 5371, Australia
M.J. DeBlasio
- Research Centre for Early Origins of Adult Disease, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, SA 5005, Australia
J.A. Owens
- Research Centre for Early Origins of Adult Disease, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, SA 5005, Australia
- Corresponding author. Tel.: +61 8 8524 9665; fax: +61 8 8524 9088.

Accepted 27 February 2008. published online 17 April 2008.

Abstract

Maternal feed allowance during pregnancy can affect the development of the ovine placenta and fetus. The impact of variations in feed allowance prior to as well as throughout pregnancy has received less attention. Ewes were offered 0.6 (R), 1.2 (C) or 1.8 (AL) maintenance requirements from 89days before conception until day 133 of pregnancy. Ewes were euthanased on days 50, 92 and 133 of pregnancy. Ewe live weight and body condition score, maternal and fetal metabolic and hormonal profiles, fetal body dimensions and organ weights, and the number, weight and morphology of placentomes were measured. Maternal live weight and condition score were lower in R compared to AL ewes at all stages of pregnancy (P<0.05). Plasma glucose and albumin concentrations of R ewes were significantly reduced (P<0.05) at mid and late gestation, respectively. Placental components were generally unresponsive to long term variations in maternal feed allowance. However, placental weight was significantly (P<0.05) correlated with fetal weight at days 50 (r=0.59) and 133 (r=0.69) of gestation. By late gestation growth-retarded singleton fetuses from R ewes were 19% lighter (P<0.05), with reduced abdominal (9%) and thoracic (10%) girths (P<0.05) but of similar crown-rump length compared with fetuses from AL ewes. These differences were associated with significantly reduced IGF-I concentrations in fetal plasma (P<0.05). In conclusion, maternal, placental and fetal adaptations to long established planes of variable maternal feed allowance were able to maintain fetal growth during early and mid-pregnancy while fetal growth restriction, associated with reduced fetal IGF-I levels, became apparent in late pregnancy.