Nutrient intake during pregnancy affects foetal development and placental function in a range of species, often with long-term effects on offspring viability. Maternal supply and placental transport of amino acids are key to delivering amino acids for foetal metabolism. Maternal under-nutrition has been shown to reduce both maternal and foetal amino acid concentrations even after a period of re-feeding (Kwon et al. 2004). Intriguingly whether sheep have been adapted to a harsh environment or not appears to influence the extent of any reduction (Jobgen et al. 2008). The present study therefore tested whether plasma amino acid concentrations differed between Scottish Blackface (B) sheep adapted to a hill environment and a lowland breed (Suffolk, S) selected for lean tissue growth when challenged by a period of under-nutrition.