MATERNAL NUTRITION IN EARLY-MID GESTATION AND PLACENTAL SIZE IN SHEEP

We investigated the influence of restricted maternal nutrition between 30 and 80 d gestation on placental growth. Singleton-bearing ewes wer e fed on either 0.6 (i.e. nutrient restricted) times their energy requ irements or 2.25 times this amount (i.e. controls) up to 80 d gestatio n, when their placentas and fetuses were sampled and analysed. Nutrien t-restricted ewes lost body condition score but not body weight and ha d lower plasma thyroid hormone concentrations than controls, but there were no differences in plasma glucose, non-esterified fatty acids or 3-hydroxybutyrate concentrations between groups. There was no effect o f maternal nutrient restriction on fetal weight, conformation or organ weights with the exception of brain weight which was lower in nutrien t-restricted ewes. Nutrient restriction had no effect on total placent al weight, or proportion of inverted placentomes, but was associated w ith an increased abundance of small placentomes and decreased weight o f the fetal but not maternal components of the placenta. Fetal cotyled ons from nutrient-restricted ewes also had a lower DNA but higher haem oglobin concentration than those sampled from controls. The plasma con centration of triiodothyronine in umbilical cord plasma was also incre ased in fetuses from nutrient-restricted ewes. In conclusion, maternal nutrient restriction during early-mid gestation is associated with a smaller placenta.