Baldassini Welder A, Ramírez-Zamudio Germán D, Duarte Marcio S, Ladeira Márcio M, Pereira Guilherme L, Machado-Neto Otavio R, Torres Rodrigo N S, de Magistri Murilo S, Camargo Lucas R, Curi Rogério A, Chardulo Luis Artur L
School of Veterinary Medicine and Animal Science (FMVZ), São Paulo State University (UNESP), 18618-681 Botucatu, SP, Brazil.
School of Agriculture and Veterinary Sciences (FCAV), São Paulo State University (UNESP), 14884-900 Jaboticabal, SP, Brazil.
J Anim Sci. 2025 Jan 4;103. doi: 10.1093/jas/skaf248.
This study evaluated the effects of neonatal vitamin A supplementation on intramuscular fat (IMF) deposition and the molecular mechanisms regulating adipogenesis and lipogenesis in Montana × Nellore crossbred beef steers. We hypothesize that neonatal vitamin A supplementation induces long-term transcriptional changes associated with IMF development. Thirty-four calves were randomly assigned to two groups: a control receiving a placebo and a treatment group receiving a single intramuscular injection of 300,000 IU of vitamin A at birth. Longissimus thoracis (LT) muscle samples were collected via biopsy at 40 days of age (cow-calf phase) and again at 400 ± 10 days of age (finishing phase) immediately after slaughter. At deboning (48 hours postmortem), LT samples were collected between the 12th and 13th ribs for chemical composition assessment. Vitamin A supplementation had no significant effect on weaning weight, average daily gain, final body weight, backfat thickness, or ribeye area (P > 0.05). However, IMF content was significantly higher (P < 0.01) in the vitamin A-supplemented (4.10%) compared to control (2.57%). Transcriptomic analysis revealed 52 and 165 differentially expressed genes (DEGs; FDR < 0.05) during the cow-calf and finishing phases, respectively. Functional enrichment analyses showed that vitamin A supplementation upregulated the actin cytoskeleton, insulin, and calcium signaling pathways during the cow-calf phase, and the PI3K-Akt, AMPK, and PPAR signaling pathways during the finishing phase. Notably, key genes associated with adipogenesis and lipogenesis, such as KRAS, ITGB6, CALML6, CISH, and ATF3 in the cow-calf phase, and LEP, ACACA, FASN, SCD, ELOVL6, and CIDEC in the finishing phase, were upregulated in response to vitamin A, as well as several adipogenic regulators, including PPARG, C/EBPA, and FABP4. Pathway enrichment analysis highlighted the PI3K-Akt signaling pathway as a central mediator of vitamin A's effects on adipocyte differentiation and lipid metabolism. Thus, neonatal vitamin A supplementation can enhance IMF deposition in beef steers by modulating key molecular pathways, without negatively impacting growth performance or carcass traits.
本研究评估了新生犊牛补充维生素A对蒙大拿×内洛尔杂交肉牛肌内脂肪（IMF）沉积的影响，以及调节脂肪生成和脂质生成的分子机制。我们假设新生犊牛补充维生素A会诱导与IMF发育相关的长期转录变化。34头犊牛被随机分为两组：一组为接受安慰剂的对照组，另一组为在出生时接受一次300,000国际单位维生素A肌内注射的处理组。在40日龄（犊牛-母牛阶段）通过活检采集胸最长肌（LT）样本，并在400±10日龄（育肥阶段）屠宰后立即再次采集。在去骨时（宰后48小时），在第12和13肋骨之间采集LT样本用于化学成分评估。补充维生素A对断奶体重、平均日增重、最终体重、背膘厚度或眼肌面积没有显著影响（P>0.05）。然而，与对照组（2.57%）相比，补充维生素A组的IMF含量显著更高（P<0.01）（4.10%）。转录组分析分别在犊牛-母牛阶段和育肥阶段揭示了52个和165个差异表达基因（DEGs；FDR<0.05）。功能富集分析表明，补充维生素A在犊牛-母牛阶段上调了肌动蛋白细胞骨架、胰岛素和钙信号通路，在育肥阶段上调了PI3K-Akt、AMPK和PPAR信号通路。值得注意的是，与脂肪生成和脂质生成相关的关键基因，如犊牛-母牛阶段的KRAS、ITGB6、CALML6、CISH和ATF3，以及育肥阶段的LEP、ACACA、FASN、SCD、ELOVL6和CIDEC，对维生素A有上调反应，还有几个脂肪生成调节因子，包括PPARG、C/EBPA和FABP4。通路富集分析突出了PI3K-Akt信号通路是维生素A对脂肪细胞分化和脂质代谢影响的核心介质。因此，新生犊牛补充维生素A可通过调节关键分子途径增强肉牛的IMF沉积，而不会对生长性能或胴体性状产生负面影响。
