The maturity in fetal pigs using a multi-fluid metabolomic approach

In mammalian species, the first days after birth are an important period for survival and the rates of mortality before weaning are high. In pigs, the perinatal deaths average 20% of the litter, with important economic and societal consequences. Among the factors influencing piglet survival at birth, the maturity is likely to be one of the most important. Maturity can be defined as the outcome of complex mechanisms of intra-uterine development and maturation occurring during the last month of gestation. Here, we provide new insights on maturity by studying the end of gestation at two different stages (three weeks before term and close to term) in two breeds of pigs that strongly differ in terms of neonatal survival. Since metabolomics is a promising approach for phenotype characterization or biomarker discovery, we provide a complete understanding of the metabolome of the fetuses in late gestation in three fluids (plasma, urine, and amniotic fluid). We found that biological processes related to amino acid and carbohy-drate metabolisms are critical for piglet maturity. We also confirmed some previously described metabolites associated with delayed growth ( e.g. , proline and myo-inositol). Altogether, our study proposes new routes for a better characterization of piglet maturity at birth.