Zinc Oxide Nanoparticles: A Comprehensive Study of Its Effects on Growth Performance and Intestinal Barrier Functions in Broiler Chickens

Nano-trace elements have gained significant attention as a promising, emerging technology in the animal feed industry in recent years. Their minute size allows for enhanced absorption and efficiency compared to conventional zinc counterparts. The present study aimed to investigate the effects of Zinc oxide nanoparticles (ZnONPs) on the growth and intestinal barrier function of broiler chicks. A total of 150 one-day-old straight-run broiler chicks were randomly allotted to 5 dietary treatment groups. The chicks were fed with a basal diet supplemented with 80 mg/kg zinc oxide (control group) or 60 mg/kg zinc methionine, or 60, 40, or 20 mg/kg ZnONPs, respectively, for 35 days., Improved feed conversion ratio (FCR) was recorded in birds fed 20 and 40 mg/kg ZnONPs, among all the treatment groups. The different treatment groups did not affect the feed intake. Compared with the control group, the villus length (VL) and crypt depth (CD) in the duodenum and jejunum were increased in the 20 mg/kg ZnONPs group. In the ileum, CD was significantly higher in all studied doses of ZnONPs. Villi length to crypt depth ratio (V/C) was higher in ZnONPs groups in the duodenum, at 20 mg/kg ZnONPs in the ileum and in the jejunum. Dietary inclusion of ZnONPs showed no significant effects on mRNA expression of the Zona Occludens-1 (ZO-1) gene, while 20 mg/kg ZnONPs significantly upregulated the mucin-2 and claudin-3 genes in the ileal mucosa. The findings of the present study suggest that ZnONPs at a lower dose (20 mg/kg) promote growth and intestinal health.