Diet Supplementation with Prinsepiae Nux Extract in Broiler Chickens: Its Effect on Growth Performance and Expression of Antioxidant, Pro-Inflammatory, and Heat Shock Protein Genes

Abstract

Heat stress significantly undermines the poultry industry by escalating rates of morbidity and mortality and impairing growth performance. Our recent findings indicate that Prinsepiae Nux extract (PNE) effectively stimulates the Nrf2 signaling pathway, a vital element in cellular antioxidant stress responses. This study further explores the prospective benefits of supplementing PNE into poultry feed to enhance broiler growth in heat-stressed conditions. An Nrf2-luciferase reporter assay was developed in a chicken fibroblast cell line, demonstrating that PNE induces Nrf2 activity in a concentration-dependent manner. Real-time RT-PCR results showed that PNE intensifies the expression of Nrf2-responsive targets such as Ho1 and Nqo1 in chicken fibroblasts. A total of 160 one-day-old Arbor Acres broiler chicks were randomly assigned into four groups, each receiving a basal diet supplemented with either 0% (control), 0.1% PNE, 1% PNE, or commercial electrolyte for 35 days. Broilers were raised in an environment where the ambient temperature exceeded 30 °C for approximately seven hours each day, fluctuating between 26 and 34 °C, which is known to induce mild heat stress. The findings reveal that a 1% PNE supplement led to a significant decrease in the feed conversion ratio (FCR) compared to the control group. Moreover, chickens supplemented with 1% PNE exhibited a substantial increase in hepatic mRNA expression of antioxidant genes, such as Nqo1, Gclc, Sod2, Cat, and heat shock protein-related genes including Hsp90 and Hsf1, and a decrease in pro-inflammatory cytokine genes Il-6 and Il-1β. Consequently, PNE holds potential as a feed supplement to strengthen the antioxidant defenses of broilers and build heat stress resilience in the poultry industry.