Effects of mild early-and mid-pregnancy under-nutrition on foetal and placental development in Scottish Blackface and Suffolk sheep

Extract

Nutrient intake during pregnancy affects foetal development and placental function in a range of species, often with long-term effects on offspring viability. Maternal nutrient supply is believed to affect the ability of the placenta to deliver nutrients to the foetus (Fowden et al., 2006). In ruminant species, the majority of placental nutrient transport occurs in specialised structures called placentomes, which are categorised into 4 types (A-D) based on their morphological appearance. In type A placentomes, maternal tissue surrounds foetal tissues, whereas type D placentomes are typically everted and have a higher ratio of foetal:maternal tissue. It has been suggested that the distribution of placentome types may reflect the ability of the placenta to deliver nutrients (Vonnahme et al., 2006). This study tested the hypothesis that levels of under-nutrition typically encountered by hill ewes during pregnancy would alter the distribution of placentome types and that the relationship between ewe nutrition and placentome type would differ between breeds selected for lean tissue growth (such as the Suffolk) compared to less selected breeds (such as the Scottish Blackface).