Fetal genotype effects on morphomics, fatty acids composition and transcriptomics in swine

Iberian pigs are more prone to obesity and metabolic alterations than other lean swine breeds, due to leptin resistance and thrifty genotype, which makes the breed susceptible to changes in amount and composition of diet. This is especially manifested during prenatal development, where nutritional deficiencies in the diet of the mother may modify offspring’s gene expression to cope with postnatal challenging conditions. This work aimed to assess the role of the genotype in the metabolic and transcriptomic changes of pig fetuses derived from undernourished pregnant sows. Pure Iberian sows were inseminated with heterospermic semen from Iberian and Large White boars to obtain IBxIB and IBxLW genotypes. The pregnancy was challenged by diminishingmaternal intake to 50% of requirements during the last 2 thirds of pregnancy. Fifty-one fetuses were obtained at Day 77 of pregnancy and 32 of them (16 from each genotype) were selected at random. Assessment of body traits showed that IBxLW fetuses were heavier and more corpulent than their IBxIB littermates (P < 0.05). Analysis of liver fatty acids (FA) showed that IBxIB had higher level of saturated FA and monounsaturated FA and lower levels of polyunsaturated FA than IBxLW fetuses (P < 0.0001). Liver transcriptome analysis resulted in 249 genes differentially expressed (DE) between the 2 genotypes (q < 0.05 and FC >1.3). Functional annotation of the DE genes revealed a downregulation of biological functions related to growth and development (e.g.: Cell survival, Cell movement, Quantity of connective tissue or Survival of organism) in IBxIB fetuses. Potential transcription factors were assessed with IPA software, which allow the prediction of upstream regulators that may explain the molecular mechanisms responsible of transcriptome differences between genetic types. We highlighted 955 potential upstream regulators, some of them being involvedin growth and development (e.g.: IGF1) and downregulated in IBxIB fetuses. Hence, our results indicate differential regulation of relevant functions and pathways involved in growth and development, which may explain the phenotypic differences among the fatty and lean swine genotypes.