Effect of Cow-Calf Supplementation on Gene Expression, Processes, and Pathways Related to Adipogenesis and Lipogenesis in Longissimus thoracis Muscle of F1 Angus × Nellore Cattle at Weaning.

The aim of this study was to identify differentially expressed genes, biological processes, and metabolic pathways related to adipogenesis and lipogenesis in calves receiving different diets during the cow-calf phase. Forty-eight uncastrated F1 Angus × Nellore males were randomly assigned to two treatments from thirty days of age to weaning: no creep feeding (G1) or creep feeding (G2). The creep feed offered contained ground corn (44.8%), soybean meal (40.4%), and mineral core (14.8%), with 22% crude protein and 65% total digestible nutrients in dry matter. After weaning, the animals were feedlot finished for 180 days and fed a single diet containing 12.6% forage and 87.4% corn-based concentrate. Longissimus thoracis muscle samples were collected by biopsy at weaning for transcriptome analysis and at slaughter for the measurement of intramuscular fat content (IMF) and marbling score (MS). Animals of G2 had 17.2% and 14.0% higher IMF and MS, respectively ( p < 0.05). We identified 947 differentially expressed genes (log 2 fold change 0.5, FDR 5%); of these, 504 were upregulated and 443 were downregulated in G2. Part of the genes upregulated in G2 were related to PPAR signaling ( PPARA , SLC27A1 , FABP3 , and DBI ), unsaturated fatty acid synthesis ( FADS1 , FADS2 , SCD , and SCD5 ), and fatty acid metabolism ( FASN, FADS1 , FADS2 , SCD , and SCD5 ). Regarding biological processes, the genes upregulated in G2 were related to cholesterol biosynthesis ( EBP , CYP51A1 , DHCR24 , and LSS ), unsaturated fatty acid biosynthesis ( FADS2 , SCD , SCD5 , and FADS1 ), and insulin sensitivity ( INSIG1 and LPIN2 ). Cow-calf supplementation G2 positively affected energy metabolism and lipid biosynthesis, and thus favored the deposition of marbling fat during the postweaning period, which was shown here in an unprecedented way, by analyzing the transcriptome, genes, pathways, and enriched processes due to the use of creep feeding.