Muscle Transcriptomic Investigation of Late Fetal Development Identifies Candidate Genes for Key Roles in Piglet Maturity

To further knowledge of piglet maturity, we have developed a microarray analysis to describe biological processes and to find candidate genes for key roles in piglet maturity. The objective was to identify which genes and biological processes are specifically involved in the difference between two extreme breeds: Large White (LW) and Meishan (MS). The LW breed is a selected breed known to show an increased rate of mortality at birth, while the MS breed presents more robust piglets at birth. MS and LW sows were inseminated with mixed semen (LW and MS) hence each litter was composed of pure fetuses (LW or MS) and crossed fetuses (LWMS from MS sows and MSLW from LW sows). To assay for changes in gene expression during piglet maturity, mRNA was isolated from 61 fetal skeletal muscle samples with 8 different conditions: two fetal gestational ages (90 or 110 days of gestation), associated with four genotypes (two extreme breeds for mortality at birth (MS and LW) and two crossed breeds (MSLW and LWMS)). MS fetuses are known to have a better survival at birth than LW fetuses. An understanding of maturity is possible with the comparison between the fetal gestational ages and between the two extreme breeds. The impact of parental genotypes is studied with the presence of crossed fetuses. After quality control and normalization, only 61 samples were conserved (represented here).