Abstract:

This experiment aimed to investigate the effects of adding quercetagetin (QG) to the diet on the slaughter performance, meat quality, serum antioxidant and immune functions, and gut microbiota of broiler chickens challenged with hydrogen peroxide (H₂O₂). A single-factor completely randomized design was adopted in the experiment. A total of 240 one-day-old Cobb broiler chickens were selected and divided into three groups: the control group (fed a basal diet+intraperitoneal injection of 1.0 mL·kg^-1 BW of normal saline at 37 days of age), the H₂O₂ group (fed a basal diet+intraperitoneal injection of 1.0 mL·kg^-1 BW of a 10% H₂O₂ solution at 37 days of age), and the QG group (fed a basal diet supplemented with 100 mg·kg^-1 QG+intraperitoneal injection of 1.0 mL·kg^-1 BW of a 10% H₂O₂ solution at 37 days of age). Each group had 8 replicates, with 10 chickens in each replicate. The experimental period lasted for 42 days in total. The results showed that: 1) Compared with the control group, the slaughter rate and leg muscle rate of broiler chickens in the H₂O₂ group were decreased (P < 0.05); The addition of QG to the diet led to no significant difference in the slaughter rate and leg muscle rate of broiler chickens compared with the control group (P>0.05). 2) Compared with the control group, the redness (a^*) of the leg muscle in the H₂O₂ group decreased significantly (P < 0.05), and the cooking loss increased significantly (P < 0.05); The addition of QG to the diet resulted in no significantly difference in the a^* value and cooking loss of the leg muscle compared with the control group (P>0.05). 3) Compared with the control group, the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), and catalase (CAT), as well as the contents of immunoglobulin A (IgA), immunoglobulin G (IgG), and complement 3 (C3) in the serum of broiler chickens in the H₂O₂ group were decreased significantly (P < 0.05), while the malondialdehyde (MDA) level and the contents of immunoglobulin M (IgM) and tumor necrosis factor-α (TNF-α) were increased significantly (P < 0.05); However, compared with the H₂O₂ group, the addition of QG to the diet significantly increased the activities of SOD, GSH-Px, T-AOC, and CAT, as well as the contents of IgA, and C3 in the serum of broiler chickens (P < 0.05), and significantly decreased the MDA level (P < 0.05). 4) Firmicutes and Bacteroidota were the dominant phyla at the phylum level in the cecum of broiler chickens. Compared with the control group, the relative abundance of Firmicutes in the H₂O₂ group decreased significantly (P < 0.05), and the relative abundance of Bacteroides in the QG group increased significantly (P < 0.05). In conclusion, the addition of 100 mg·kg^-1 of QG to the diet can mitigate the adverse effects of H₂O₂-induced oxidative stress on the slaughter performance and meat quality of broiler chickens by enhancing antioxidant and immune functions and optimizing the structure of the cecal microbiota. This provides a theoretical basis for the scientific application of QG in the healthy farming of broiler chickens.

Key words: quercetagetin, hydrogen peroxide, broiler, antioxidant capacity, gut microbiota