The effect of in utero nutrient restriction on glucose and insulin metabolism in Merino sheep

Abstract

The aim of this experiment was to determine whether the magnitude of seasonal nutrient restrictions experienced by pregnant ewes in typical Australian Mediterranean farming conditions is sufficient to induce changes in glucose or insulin metabolism in the offspring at the age of eight months. Pregnant Merino ewes were fed to either maintain a body condition score of 3 throughout pregnancy or decrease condition score from 3 to 2 by the fourth month of pregnancy. Animals were then grazed at stocking rates calculated to provide either 2500 or 900 kg DM/ha until weaning, and grazed as one flock thereafter. Birth weight was not affected by pre-natal treatment, but liveweight at eight months of age was increased by the high post-natal plane of nutrition. There were no differences between post-natal treatments for any of the other variable studied. There were no effects of pre-natal treatment on the insulin or glucose response to a glucose challenge. Lambs born to ewes fed to lose condition score during pregnancy had lower basal glucose concentrations after the first day of insulin challenges and as a result showed a smaller glucose response to insulin administration at levels of 200, 300 and 500 mU/kg W. It was concluded that a level of nutrition comparable with that experienced by unsupplemented pregnant ewes on many typical Australian farms in the Mediterranean climate zone was sufficient to result in altered glucose metabolism in the offspring at the age of eight months.