Oxidative stress suppresses animal health, performance, and production, subsequently impacting economic feasibility; hence, maintaining and improving oxidative status especially through natural nutrition strategy are essential for normal physiological process in animals. Phytochemicals are naturally occurring antioxidants that could be considered as one of the most promising materials used in animal diets in various forms. In this review, their antioxidant effects on animals are discussed as reflected by improved apparent performance, productivity, and the internal physiological changes. Moreover, the antioxidant actions toward animals further describe a molecular basis to elucidate their underlying mechanisms targeting signal transduction pathways, especially through the antioxidant response element/nuclear factor (erythroid-derived 2)-like 2 transcription system.

This study evaluated the antioxidant ability of Taisung No. 3 mulberry leaf extract (MLE) as well as the potential of mulberry leaf (ML)-based dietary supplementation for modulating the antioxidative status of laying hens. The results showed that the MLE had a total phenolic compound content of 7.4 ± 0.15 mg of gallic acid equivalent/g dry weight (DW) and a total flavonoid content of 4.4 ± 0.19 mg of quercetin equivalent/g DW. The 2, 2-diphenyl-1-picrylhydrazyl free-radical-scavenging ability was 45.9% when 0.1 mg/mL MLE was added. The lipid oxidation inhibition ability was 43.9% when 50 mg/mL MLE was added. We subjected 96 laying hens (Hendrix Genetics) to 4 treatments, namely diets supplemented with dry ML at 0 (control), 0.5, 1, or 2% for 12 weeks. Each treatment involved 8 replicates with 3 hens each. The results indicated that the 0.5% ML-supplemented group exhibited significantly higher mRNA levels of antioxidant-regulated genes, such as Nrf2, HO-1, and GST, and significantly lower ROMO1 gene expression levels at wk 12. The serum malondialdehyde level was lower and the catalase activity and superoxide dismutase activity were higher in all the ML-supplemented groups than in the control group. The egg mass and feed conversion rate significantly improved in the ML-supplemented groups compared with the control group, and, overall, 1% ML supplementation had the most favorable effects at one to 12 weeks. The egg yolk weight, shell weight, shell strength, shell thickness, yolk color, and Haugh unit were increased among all ML-supplemented groups at one to 12 weeks. On the basis of these observations, we conclude that 0.5% ML can be used as a new feed additive to potentially modulate the antioxidative status of laying hens and improve their production performance and egg quality.

Phytochemicals which exist in various plants and fungi are non-nutritive compounds that exert numerous beneficial bioactive actions for animals. In recent years following the restriction of antibiotics, phytochemicals have been regarded as a primal selection when dealing with the challenges during the producing process in the poultry industry. The selected fast-growing broiler breed was more fragile when confronting the stressors in their growing environments. The disruption of oxidative balance that impairs the production performance in birds may somehow be linked to the immune system since oxidative stress and inflammatory damage are multi-stage processes. This review firstly discusses the individual influence of oxidative stress and inflammation on the poultry industry. Next, studies related to the application of phytochemicals or botanical compounds with the significance of their antioxidant and immunomodulatory abilities are reviewed. Furthermore, we bring up nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and nuclear factor kappa B (NF-κB) for they are respectively the key transcription factors involved in oxidative stress and inflammation for elucidating the underlying signal transduction pathways. Finally, by the discussion about several reports using phytochemicals to regulate these transcription factors leading to the improvement of oxidative status, heme oxygenase-1 gene is found crucial for Nrf2-mediated NF-κB inhibition.

Soybean hulls are a by-product of soybean processing for oil and meal production; Pleurotus eryngii stalk residues (PESR) are by-products of the edible portion of the fruiting body enriched in bioactive metabolites. This study evaluated the effects of co-fermented PESR and soybean hulls with Aureobasidium pullulans on performance and intestinal morphology in broiler chickens. The in vitro experimental results showed that xylananse and mannanase activity of solid-state fermented soybean hulls (100% SBH) and soybean hulls partially replaced with PESR (75:25, SHP) reached peak at day 12; solid-state fermentation (SSF) enhanced the total phenolic content and trolox equivalency in both products as well. Additionally, FSHP had higher xylotriose and mannobiose levels than fermented FSBH did. A total of 400 broilers (Ross 308) were assigned randomly into four groups receiving the basal diet (control) or the basal diet supplemented with 0.5% fermented SBH (0.5% FSBH), 0.5% fermented SBHP (0.5% FSHP) and 1.0% fermented SBHP (1.0% FSHP) until 35 d of age, respectively. Results demonstrated that 0.5% FSHP addition increased body weight gain as compared with corresponding normal diet fed control in birds during entire experimental period. Compared with the control group, 0.5% FSHP group significantly increased the ratio of lactic acid bacteria to Clostridium perfringens in ceca as well as ileum villus height and jejunum villus height/crypt depth ratio of 35 d old birds. In conclusion, 0.5% FSHP supplementation in the diet could obtain not only improved body weight gain, but optimal intestinal morphology by exerting its bioactive metabolite properties when fed to broilers.

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