Vitamin A–Enriched Diet at Late Gestation Affects Intramuscular Fat Deposition in Beef Offspring

We aimed to assess the impact of vitamin A supplementation in beef cows at late gestation on intramuscular adipogenesis in the offspring. Thirty pregnant beef cows were randomly assigned to a control group (CON; n = 15) fed a diet containing 4.1 KIU of vitamin A per kilogram, and to a vitamin A–supplemented group (VITA; n =15) fed a diet containing 12.2 KIU of vitamin A per kilogram. The treatment application occurred from 180 d of gestation until parturition. Calves were biopsied within 10 d of age to collect skeletal muscle samples for assessing gene expression and protein abundance of target genes/proteins related to adipogenesis. All calves were raised under the same conditions until slaughter at 479 ± 1.6 d of age. Cows from both treatments showed no differences (P > 0.05) in total gain and final body weight, although CON cows tended to exhibit greater (P = 0.06) dry matter intake. Skeletal muscle of newborns from the VITA group exhibited increased mRNA expression of retinoic acid receptor β (RARβ; P = 0.05), whereas no differences (P > 0.05) were observed in mRNA expression of markers for fibroadipogenic progenitor cells (PDGFRα) and adipogenesis (ZFP423 and PPARγ). However, skeletal muscle of newborns from the VITA group showed greater protein abundance of DLK1 (P < 0.01) and PPARγ (P = 0.03) than those from the CON group. No differences (P > 0.05) among treatments were observed in the abundance of retinoid X receptor and PDGFRα . Repeated carcass ultrasound measurements of the offspring showed increased intramuscular fat content throughout all the evaluated stages of their post-natal life (P < 0.05), while no changes were observed within subcutaneous fat measurements (P > 0.05). Hot carcass weight, carcass yield and dressing percentage, and kidney pelvic heart (KPH) fat percentage were not affected by treatment (P > 0.05). These findings suggest that vitamin A supplementation during late gestation enhances intramuscular adipogenesis in offspring.