69 Late-Breaking: Maternal vitamin and mineral supplementation during gestation affects multi-tissue regulatory network in neonatal beef calves.

Abstract Vitamins and minerals are essential for regulating gene expression and physiological processes, particularly during gestation when maternal nutrient demands increase to support fetal development. We investigated how maternal mineral supplementation influences gene co-expression networks across multiple tissues in neonatal calves. Crossbred Angus heifers were fed either a basal diet (CON; n = 7) or the basal diet plus 113 g/heifer/day of VTM supplement (VTM; n = 7), starting 60 days before breeding and continuing throughout gestation. Neonatal female calves were euthanized 30 h after birth, and samples of the jejunum, liver, and muscle were collected. Placental tissue was collected after natural delivery from a separate cohort a month earlier but under similar treatment conditions. RNA-Seq was performed on these tissues to build tissue-to-tissue regulatory networks and assess differentially expressed genes (DEGs). Using DESeq2, we identified 1,608 DEGs between VTM and CON groups across tissues, with 529 in the jejunum, 633 in the liver, 312 in the muscle, and 134 in the placenta (P ≤ 0.05 and |log2FC > 0.5|). The tissue-specific analysis identified 205 genes, with 32 in the placenta, 42 in the liver, 34 in the jejunum, and 97 in the muscle. Functional analysis using TopAnat highlighted enriched pathways related to skeletal muscle development, adipose tissue, and immune function. Tissue-to-tissue networks constructed with PCIT identified 1,005 correlated pairs (|r >0.9|; P < 0.05). Among the correlated pairs were GATA3 and WNT4 genes (r = 0.95). GATA3, a key immune regulator, is a tissue-specific gene in the placenta. Additionally, it showed a high regulatory potential of the DEGs in the jejunum. WNT4, upregulated in the muscle of calves born from the VTM group, has been associated with adipocyte differentiation and myogenic proliferation and differentiation. Our results suggest that vitamin and mineral supplementation during gestation affects gene expression across tissues, shaping offspring development through interconnected regulatory networks. Further research is needed to investigate the long-term implications of these changes on animal health and performance.