Effects of maternal intake restriction during early pregnancy on fetal growth and bone metabolism in goats

The objective of this study was to investigate the effects of maternal nutritional restriction on fetal growth and bone metabolism in early pregnancy. Twelve twin-bearing goats (Xiangdong black goats) in second pregnancy, with similar weight (31.2 +/- 8.1 kg) and age (2.0 +/- 0.3 year) were assigned to two dietary treatments in early gestation (26-65 days): control group (CON, 100% feed) and intake restriction group (IR, 60% of CON intake). The umbilical blood, right femur and liver of the fetuses were sampled on day 65 to determine the bone metabolism indicators and expression of genes involved in bone development. Maternal intake restriction did not affect the growth performance of pregnancies (P > 0.05), increased (P < 0.05) the body weight, body length, thoracic circumference and umbilical circumference of fetal goats, but decreased (P < 0.05) the concentrations of cross-linked N-terminal telopeptides of type I collagen and cross-linked C-terminal telopeptides of type I collagen, which involved in bone metabolic activity, in the fetal umbilical blood of the IR. In fetal femurs, the mRNA expression of bone gamma-carboxyglutamate protein, osteoprotegerin and mothers against decapentaplegic homolog 1 both participating in osteoclast differentiation were increased (P < 0.05), whereas transcript of the low density lipoprotein receptor related protein 5 involved in osteoblast differentiation was decreased (P < 0.05), compared with the fetuses from the CON. These results indicate that nutrition restriction in early pregnancy regulated the fetal growth and promoted formative activity of femur. The molecular mechanism of maternal intake restriction on bone metabolism needs further investigation.