Abstract The objective was to evaluate the effects of Nellore cows supplementation, during mid to late gestation, on beef quality and expression of genes involved in the deposition of fat and collagen in the muscle of progenies fed diets with or without high inclusion of rumen-protected fat. Forty Nellore steers with an initial average body weight of 340 + 9.38 kg were distributed in a completely randomized design, and arranged in a 2 × 2 factorial design. Therefore, the following treatments were assessed: nutritional management of cows without supplementation (NSUPP); or with supplementation (SUPP: 330 g CP and 2.11 Mcal/cow/day); and progeny feedlot diets without rumen-protected fat (NRPFAT) or with rumen-protected fat (RPFAT: 6% calcium salts). Samples of longissimus thoracis muscle were used for meat quality analyses: pH, color, chemical composition and 14 days aging shear force; and for gene expression analysis using the RT-qPCR. Statistical analyses were done using the GLM procedure of SAS. The maternal supplementation and the use of RPFAT in feedlot diets did not affect muscle pH (5.7; SEM +0.029), L* (40.0; SEM +1.231), a* (11.9; SEM +0.876), fat content (2.3%; SEM +0.306), collagen (1.43 mg/g; SEM +0.08), and shear force (4.2 + 0.322 kgf). However, cows’ supplementation increased the expression of CPT2 and tended to up-regulate FASN and ACACA expression (Table 1). In addition, RPFAT increased expression of COL3A, FN1, IGFR1, and ACACA. There was no interaction effect of cow supplementation on gene expression. These results suggest that maternal supplementation may increase the expression of genes related to lipid synthesis and degradation (lipid turnover). On the other hand, the use of high amount of calcium salts increases the expression of genes involved in collagen synthesis but with no effect on collagen content and tenderness. Funded by Trow Nutrition, Fapemig, INCT-Ciência Animal and Capes.