Nano-ZnO Improves IUGR-Induced Abnormal Fat Deposition in Finishing Pigs by Remodeling the Intestinal Microbiota and Regulating Serum Metabolism.

Intrauterine growth retardation (IUGR) in pigs is closely associated with excessive obesity and lipid metabolic abnormalities during postnatal catch-up growth. Nano zinc oxide (Nano-ZnO) is a novel nanomaterial that has antioxidant properties and can improve abnormal lipid metabolism. This study aimed to investigate the weight-reducing effects and mechanisms of Nano-ZnO in IUGR pigs. Six normal birth weight (NBW) and twelve IUGR male piglets were divided into three groups post-weaning (day 22): NBW and IUGR groups received a basal diet, while the IUGR + Zn group was fed a Nano-ZnO-supplemented diet (600 mg/kg). Nano-ZnO significantly reduced backfat thickness and improved fatty acid composition in IUGR pigs. Mechanistically, Nano-ZnO activated the NRF2 signaling pathway, enhancing antioxidant capacity in adipose tissue by elevating T-SOD and T-AOC activities, upregulating SOD/GCLC/GCLM expression, and suppressing KEAP1 and MDA levels. Concurrently, it promoted lipolysis via the adiponectin/AMPK/SREBP1C/PPARγ axis, increasing ACC/CPT-1/HSL activity and mRNA expression while inhibiting FAS. Furthermore, Nano-ZnO modulated gut microbiota composition (e.g., increasing cecal UCG-005, Rikenellaceae RC9, and fecal Phascolarctobacterium) and serum metabolites (e.g., reducing phenylpyruvic acid and 9(10)-EpOME, elevating docosahexaenoic acid and glycochenodeoxycholic acid). These findings demonstrate that Nano-ZnO ameliorates abnormal fat deposition in IUGR pigs through coordinated antioxidant, lipolytic, gut microbial, and metabolic reprogramming.