‘Under nutrition’ has no effect on the transport of nutrients from ewe to lamb in early pregnancy
Take Home Message: Modest restrictions in early pregnancy ewes will not adversely affect the placentas ability to transfer nutrients to the growing lamb.
A Scottish study has confirmed that the ability of the placenta to transport nutrients, from ewe to lamb, is not compromised by modest reductions in feed intake during the first 90 days of pregnancy. Good news for sheep producers who may be worried about pregnant ewes grazing in harsh environments.
“And higher foetal to maternal amino acid ratios for Suffolk ewes suggests a superior ability to transport amino acids, which may be because of greater placental mass or placental efficiency,” SAC scientist John Rooke told delegates at 2009’s British Society of Animal Science annual conference.
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 vital 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’. Intriguingly whether sheep have been adapted to a harsh environment or not appears to influence the extent of any reduction.
“Our study 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,” said Dr Rooke.
Oestrous cycles of the ewes were synchronised and ewes were inseminated with semen from a single sire of each breed. All ewes received concentrate and straw-based rations from day one to day 90 of gestation inclusive. During this time, half the ewes received a restricted diet calculated to supply 0.8 x maintenance energy requirements (R), while the remaining ewes received control (C) rations supplying 1.0 x maintenance energy requirements.
“The most abundant amino acids, in decreasing order of concentration, in maternal plasma were glycine, glutamine and alanine and in foetal plasma, glutamine, alanine and serine. After a period of re-feeding, differences in amino acid concentration as a result of under nutrition were few and restricted to maternal glutamic acid, glutamine and foetal glycine,” said Dr Rooke.
“However, the ratio of foetal to maternal amino acids was consistently greater in Suffolk than Blackface ewes with the differences being most marked for the acidic and branched chain amino acids,” he added.
To view proceedings of all summaries presented at the Annual Conference 2009
http://www.bsas.org.uk/Publications/Annual_Conference_Proceedings/ To view all Powerpoint presentations http://www.bsas.org.uk/Members_Area/ For further information contact: BSAS on 0131 445 4508 or bsas@sac.ac.uk
