This study purposed to investigate the alleviating effect of dietary curcumin supplementation on oxidative stress in the liver of broilers induced by diquat. One-day-old Cobb broilers (400) were selected and randomly divided into 5 groups, with 8 replicates and 10 broilers per replicate. The control group and the diquat group were fed the basal diet, while the curcumin supplementation groups were fed the basal diet supplemented with different amounts of curcumin (50, 100, and 150 mg/kg). On d 21 of the test, 1 broiler was randomly selected from each replicate and intraperitoneally injected with 20 mg/mL of diquat solution at a dose of 1 mL/kg BW or equivalent physiological saline (for the control group). After 48 h of feeding, the selected broilers were slaughtered for analysis. The results show that diquat treatment reduced the antioxidant capacity of the liver, caused oxidative stress, and affected its lipid metabolism. However, diet supplementation using curcumin completely or partially reversed the effect of diquat on the liver of broilers. The blood alanine aminotransferase activity, total bilirubin and total protein levels, and liver Caspase-3 mRNA abundance in broilers were lower or significantly lower in the curcumin supplementation group than in the diquat group (P < 0.05). The curcumin supplementation groups had significantly higher total antioxidant capacity activity but significantly lower malondialdehyde in the liver of broilers than the diquat group (P < 0.05). The blood triglyceride level of broilers was lower or significantly lower in the curcumin supplementation groups than in the diquat group (P < 0.05). The activities of cetyl coenzyme A carboxylase in the liver were significantly lower in the 150 mg/kg curcumin supplementation groups than in the DQ group (P < 0.05). In conclusion, dietary curcumin supplementation could ameliorate the effects of diquat-induced oxidative stress on the antioxidant capacity, tissue morphology, and lipid metabolism of the liver of broilers, thus protecting the liver. The recommended dosage for broiler diets is 100 to 150 mg/kg curcumin.

Ursolic acid (UA) has demonstrated significant immunomodulatory and hepatoprotective effects; however, the underlying mechanisms remain unclear. This study aims to analyze the impact of UA on the gut microbiome, metabolome, and liver transcriptome, investigate UA’s role in maintaining gut immune homeostasis and liver health, and evaluate the potential contributions of gut microbes and their metabolites to these beneficial effects. Our findings indicate that UA enhances immune balance in the jejunum, fortifies intestinal barrier function, and promotes overall gut health. UA modulates the intestinal microbiota and its metabolic processes, notably increasing the abundance of beneficial bacteria such as Odoribacter and Parabacteroides, along with their metabolites, including ornithine and lactucin. Additionally, UA inhibits the expression of interleukin-1 receptor 1 (IL1R1) and calcium (Ca²⁺) voltage-gated channel auxiliary subunit beta 2 (CACNB2) while enhancing the synthesis pathways of retinol and ascorbic acid, thereby exerting a protective influence on liver function. In summary, UA enhances intestinal immune homeostasis and promotes liver health, with these advantageous effects potentially mediated by beneficial bacteria (Odoribacter and Parabacteroides) and their metabolites (ornithine and lactucin).

This study evaluated the alleviative effect of curcumin (CUR) on the diquat (DQ)-induced cecal injury in broilers. A total of 320 one-day-old Cobb broilers were selected and randomly divided into 4 treatments, namely control, DQ, CUR 100, and CUR150 groups. The control and DQ groups were fed a basal diet, while the CUR 100 and CUR150 groups were fed the basal diet supplemented with 100 and 150 mg/kg CUR, respectively. Each group had 8 replicates, with 10 broilers per replicate. On day 21 of the experiment, 1 broiler was selected from each replicate and intraperitoneally injected 20 mg/kg body weight of DQ for DQ, CUR 100, and CUR 150 groups. Broilers in control group received equivalent volume of saline. Broilers were euthanized 48h postinjection for tissue sampling. The results showed that DQ injection could cause oxidative stress and inflammatory reactions in the cecum, affecting the fatty acid production and flora structure, thus leading to cecum damage. Compared with the DQ group, the activity of superoxide dismutase, the level of interleukin 10, acetic acid, and total volatile fatty, and the abundance of nuclear factor E2-related factor 2, copper and zinc superoxide dismutase and catalase mRNA in the cecal mucosa of broilers in the CUR group increased significantly (P < 0.05). However, the levels of malondialdehyd, reactive oxygen species, tumor necrosis factor-alpha, and the expression of cysteine-aspartic acid protease-3 and tumor necrosis factor-alpha decreased significantly (P < 0.05) in the CUR group. In addition, CUR treatment alleviated the damage to the cecum and restored the flora structure, and Lactobacillus and Lactobacillaceae promoted the alleviative effect of CUR on DQ. In summary, CUR could alleviate the cecal injury caused by DQ-induced oxidative damage and inflammatory reactions by regulating the Nrf2-ARE signaling pathway and intestinal flora, thus protecting the cecum.

This study investigated the dietary effect of curcumin (CUR) on amino acid, 5′-nucleotides, fatty acid, and volatile compound profiles of chicken meat. A total of 400 healthy 1-day-old broiler male chicks were divided into 4 groups (n = 10) and fed either a basal diet or a diet with the addition of CUR with concentrations of 100 mg/kg, 150 mg/kg, and 200 mg/kg for 43 days. The results show that the addition of CUR in chicken diets is conducive to promoting the deposition of amino acids and increasing the content of 5′-nucleotides in chicken meat, reducing the contents of saturated fatty acid (SFA) and C20:4 n6 but increasing the ratio between polyunsaturated fatty acid (PUFA) and SFA. In addition, the volatile compound profile shows that the main volatile compounds in chicken meat are aldehydes (including hexanal, heptanal, octanal, and nonanal), with significant increases in their contents observed among chickens in the CUR-intake group. Moreover, it has been found that (E, E)-2,4-nonadienal, trans-2-decenal, benzaldehyde, and trans-2-octenal in chicken meat can significantly increase its overall aroma, and the addition of CUR with 150 mg/kg had the best effect on improving nutritional quality and flavor of chicken meat. This study provides a basis for the comprehensive utilization of CUR as a feed additive with the potential to substitute antibiotics.

This study aimed to investigate the effects of dietary supplementation with different levels of ursolic acid (UA) on the growth performance, immune function, intestinal antioxidant capacity, and anti-inflammatory responses of weaned rabbits. A total of 160 Hyla meat rabbits aged 35 days were randomly assigned to four groups. Each treatment group consisted of 8 replicates, with 5 rabbits per replicate. The rabbits were fed a basal diet (control group, CON) or experimental diets supplemented with 50, 100, or 200 mg/kg UA for 28 days. Dietary supplementation with 50 mg/kg UA significantly increased (p < 0.05) the average daily gain and average daily feed intake. The villus height, crypt depth, and villus height to crypt depth ratio exhibited quadratic responses (p < 0.05) to increasing dietary UA levels, with rabbits fed 50 mg/kg UA showing optimal ileal morphology. Compared with the CON group, dietary supplementation with 50 mg/kg UA significantly enhanced (p < 0.05) cecal catalase activity, secretory immunoglobulin A, and interleukin-10 (IL-10) levels, while the addition of 200 mg/kg UA increased (p < 0.05) serum catalase activity. The concentrations of serum tumor necrosis factor-α (TNF-α) and cecal IL-10 responded quadratically (p < 0.01 and p = 0.01, respectively) as the dietary UA level increased. With increasing UA supplementation, cecal Kelch-like ECH-associated protein 1 and IL-10 mRNA expression showed linear upregulation (p < 0.05), whereas nuclear factor erythroid 2-related factor 2 (Nrf2), superoxide dismutase 1 (SOD1), quinone oxidoreductase 1 (NQO1), TNF-α, interleukin-6, and interleukin-8 displayed quadratic responses (p < 0.05). Dietary UA at 50 mg/kg significantly downregulated cecal TNF-α and interleukin-1β mRNA expression while upregulating Nrf2, NQO1, and SOD1 mRNA levels (p < 0.05). In conclusion, dietary supplementation with 50 mg/kg UA significantly improved the growth performance of weaned rabbits by improving intestinal morphology, immune function, and antioxidant and anti-inflammatory capacities, demonstrating its efficacy as a natural phytogenic feed additive.