Zinc oxide quantum dots enhanced growth performance and zinc metabolism in weaned piglets.

The widespread use of conventional high-dose zinc oxide (ZnO) for diarrhea prevention and growth promotion in weaned piglets carries risks of toxicity, bacterial resistance, and environmental harm. This study assessed zinc oxide quantum dots (ZnO-QDs) as a safer, effective alternative. In vitro antibacterial tests demonstrated that, at the same dosage, ZnO-QDs exhibited superior antimicrobial activity compared to conventional ZnO. Subsequent animal trials were conducted using 192 weaned piglets (Duroc × Landrace × Yorkshire; age=21d old; BW=7.70 ± 0.20 kg), which were randomly assigned to four dietary treatment groups (CON, 2-ZnO, 1-ZnO-QDS and 0.5- ZnO-QDS) in a completely randomized design. Results showed that, comparable under the present conditions, lower doses of ZnO-QDs (500 mg/kg, 0.5- ZnO-QDS) provide growth and anti-diarrheal benefits equal to higher doses of conventional ZnO (2000 mg/kg, 2-ZnO) (P > 0.05). ZnO-QDs upregulated jejunal ZIP-1, ZIP-5, ZIP-9 and ZIP-13 gene expression (P < 0.05) for zinc transport and increase total antioxidant capacity in serum (P < 0.01). Importantly, it also improved intestinal health, as evidenced by increased villus height in the duodenum (P < 0.05) and modulation of gut microbiota composition. Substituting conventional ZnO with 500 mg/kg ZnO-QDs could effectively promote piglet growth and reduce diarrhea, while decreasing zinc emissions and environmental impact.