INFLUENCE OF RESTRICTED MATERNAL NUTRITION IN EARLY TO MID GESTATION ON PLACENTAL AND PETAL DEVELOPMENT AT TERM IN SHEEP

We investigated the influence of restricted maternal nutrition between 28 and 77 d of gestation on placental weight and appearance, and on f etal weight and conformation. Single-bearing ewes were fed either twic e [i.e, controls (n = 19)] or half [i.e. nutrient-restricted (n = 28)] their energy requirements from 28 to 77 d of gestation, after which a ll ewes were fed to fully meet the energy requirements for maintenance and pregnancy. Close to term (145 +/- 1 d) placental weight was highe r in the nutrient-restricted group [nutrient-restricted, 416.3 +/- 12. 6 g; controls, 347.3 +/- 17.6 g (p < 0.01)], as was the abundance of e verted placentomes. There was no significant difference in total fetal weight, or weights of individual organs between groups, but crown-rum p length was significantly greater in lambs born to nutrient-restricte d ewes [nutrient-restricted, 50.4 +/- 0.4 cm; controls, 48.2 +/- 0.6, cm (p < 0.01)]. Fetal to placental weight ratio was lower in the nutri ent-restricted group [nutrient-restricted, 9.51 +/- 0.23; controls, 10 .81 +/- 0.39 (p < 0.01)]. A stronger relationship between the total we ight of the fetal component of the placental and fetal weight was obse rved in controls (r(2) = 0.50) than in nutrient-restricted ewes (r(2) = 0.18). In conclusion, maternal nutrient restriction over the period of rapid placental growth results in a larger placenta and altered pla cental to fetal weight ratio if ewes are subsequently fed to requireme nts for the remainder of gestation.