The effect of overnourishing singleton-bearing adult ewes on nutrient partitioning to the gravid uterus

Overnourishing the singleton-bearing adolescent sheep throughout pregnancy promotes maternal tissue synthesis at the expense of the nutrient requirements of the gravid uterus. Consequently, the growth of the placenta is impaired and results in the premature delivery of low-birth-weight lambs relative to moderately fed adolescents of equivalent age. To establish if this phenomenon is unique to the growing animal, singleton pregnancies to a single sire were established by embryo transfer into primiparous adult ewes who had attained the normal mature body size for their genotype. Thereafter ewes were offered a maintenance or a high level of a complete diet throughout gestation. High maternal intakes resulted in elevated maternal insulin, no significant change in growth hormone or glucose, and attenuated progesterone and NEFA concentrations. Live weight gain during the first 93 d of gestation was 48 and 244 g/d, and adiposity score at term was 2·4 and 3·7 in the maintenance and high groups, respectively (P