PSI-10 - Effects of a methylation blend supplemented diet during gestation and lactation on skeletal muscle growth and molecular characteristics in piglets

Abstract: We aimed to investigate the impact of a mixed diet supplemented with a blend of methyl group carrier, cofactors, long chain fatty acid transporter and plant polyphenols (methylation blend) during gestation and lactation of sows on muscle growth and molecular characteristics of their offspring. A total of 260 sows (parity 1-9) were randomly assigned to one of the following treatments: Control (CON, n = 130) where sows received a common commercial diet, or a propriety methylation blend supplemented diet (MET, n = 130) during the entire gestation and lactation. A subset of piglets (one piglet per litter, 16 piglets per treatment) was chosen and euthanized at age of 1 to 5d for the collection of the Longissimus dorsi muscle for histological and molecular biology analyses. The data analyses were performed using linear mixed effect model through R environment with treatment as fixed and sow group, parity, and day of sampling as random effect. Histological analysis of the skeletal muscle in piglets showed no significant difference in muscle hyperplasia between groups. However, there was a tendency of greater muscle hypertrophy, as indicated by muscle fiber size, in the MET group (P = 0.09). The mRNA expression of the myogenic markers (MyoG, MyoD, and MRF4) was similar in the skeletal muscle of piglets from CON and MET group. Moreover, the mRNA expression of the receptor of insulin-like growth factor (IGF1R, and IGF2R), and the inhibitor of muscle differentiation and growth (MSTN) did not differ between groups. Regarding the protein abundance of the markers of fibro-adipogenic progenitor cells (PDGFRα) and the marker of preadipocyte (DLK1), no differences between treatments were observed in the skeletal muscle of piglets. However, protein abundance of PAX7, a satellite cell marker, tended to be lower (P = 0.058) in the skeletal muscle of MET piglets. Skeletal muscle DNA methylation tended (P = 0.061) to be higher in MET-piglets indicating potential changes in gene transcription. Indeed, RNA-seq data showed a total of 20 differentially expressed genes (P < 0.10 and a Fold Change >|1.5|). In general, the enriched biological processes of the DE genes are related to ribosome assembly, Golgi to endosome transport, plasma membrane to endosome transport, regulation of RNA polymerase II, and chaperone cofactor-dependent protein refolding. In conclusion, supplementing sows with a proprietary methylation blend during gestation and lactation positively regulated offspring muscle hypertrophy, and induced DNA hypermethylation, potentially altering the mRNA transcriptional process, and affecting the overall protein synthesis and functionality, particularly through the protein folding process.