Table 1.

Effects of supplementary phytochemicals on oxidative status of poultry under cyclic chronic heat stress (CyCHS), constant chronic heat stress (CoCHS), and acute heat stress (AHS) (the birds were sampled at the end of HS, unless otherwise stated). Signicant effects on parameters of oxidative status are given for dietary treatments under HS conditions as compared to a heat stressed control (i.e. Cont. or T1). In case, both a non heat stressed (non supplemented) and heat stressed (non supplemented) control are included, data are used to confirm the presence of heat stress

Heat stress model	Poultry species and diets	Significant results	Reference
At d 10 of age for 32 d were exposed to: 1. Cont. at 22 °C 2. CyCHS at 34 °C for 8 h/d, (RH = 44 %) A 2×4 factorial design	Japanese quails; dietary treatments starting at d 10 of age 1. Cont.; 2. Cont. + genistein (GN) at 200 mg/kg; 3. Cont. + GN at 400 mg/kg; 4. Cont. + GN at 800 mg/kg	Serum, liver: MDA ↓ by GN vs. Cont. Serum: homocysteine ↓ by GN vs. Cont.; vitamins C, E, A ↑ by GN vs. Cont.	[43]
At wk 60 of age for 28 d all groups were exposed to CoCHS at 32 °C	Hy-Line laying hens; dietary treatments starting at wk 60 of age 1. Cont.; 2. Cont. + Schisandra chinensis (SC) at 10 g/kg; 3. Cont. + Ligustrum lucidum (LL) at 10 g/kg	Serum, liver, heart, egg yolk: MDA ↓ by SC and LL vs. Cont. Serum, kidney, liver: GR activity ↑ by SC and LL vs. Cont. Heart: GR activity ↑ by LL vs. Cont.	[64]
At d 10 of age for 32 d were exposed to: 1. Cont. at 22 °C, (RH = 57 %) 2. CyCHS at 34 °C for 8 h/d, (RH = 42 %) A 2×4 factorial design	Japanese quails; dietary treatments starting at d 10 of age 1. Cont.; 2. Cont. + lycopene at 50 mg/kg; 3. Cont. + lycopene at 100 mg/kg; 4. Cont. + lycopene at 200 mg/kg	Serum, liver, heart: MDA linear ↓ by lycopene vs. Cont. Serum: homocysteine linear ↓; vitamins C, E, A linear ↑; all by lycopene vs. Cont.	[69]
At d 0 of age for 49 d all groups were exposed to CoCHS at 38.6 ± 1.30 °C, (RH = 64 ± 6.0 %) On d 21 and 35 (RBS) and d 49 (other tissues) after starting HS birds were sampled	Cobb broilers; dietary treatments starting at d 0 of age 1. Cont., T1; 2. Cont. + vitamin E at 200 mg/kg, T2; 3. Cont. + dry powdered leaves of Mentha longifolia (DPLM) at 10 g/kg, T3; 4. Cont. + DPLM at 30 g/kg, T4; 5. Cont. + mix of Emblica officinalis fruit, vitamin E and electrolytes at 1 g/kg, T5	RBC: MDA ↓ by T2, T3, T4, T5 vs. T1 at d 21 and 35; GSH content ↑ by T3, T4, T5 vs. T1 at d 35; CAT, SOD, GR activity ↑ by T2, T3, T4, T5 vs. T1 at d 21 and 35 Heart, liver, brain cortex: MDA ↓ by T2, T3, T4, T5 vs. T1 at d 49; SOD, GR activity ↑ by T2, T3, T4, T5 vs. T1 at d 49	[67]
At d 3 of age for 39 d all groups were exposed to CoCHS at 32 ± 1 °C, (RH = 44 ± 6 %) On d 18 and 39 after starting HS birds were sampled	Male Arbor Acres broilers; dietary treatments starting at d 3 of age 1. Cont., T1; 2. Cont. + vitamin C at 200 mg/kg, T2; 3. Cont. + extract from dried fruits of Forsythia suspensa (FSE) at 100 mg/kg, T3	Serum: TAOC ↑ by T2, T3 vs. T1 at d 18 and 39; MDA ↓ by T2, T3 vs. T1 at d 18 and 39; SOD activity ↑ by T3 vs. T1 at d 18 Liver: MDA ↓ by T3 vs. T1 at d 39; SOD activity ↑ by T2, T3 vs. T1 at 18 and by T3 vs. T1 at d 39 Muscle: SOD activity ↑ by T3 vs. T1 at d 39; MDA ↓ by T2, T3 vs. T1 at d 39	[65]
At 1 kg BW for 20 d were exposed to: 1. Cont. at 30 °C, (RH = 65 %) 2. CyCHS at 40 ± 1 °C for 5 d out of 20 d for 4 h/d, (RH = 80 ± 5 %) 3. CyCHS at 40 ± 1 °C for 10 d out of 20 d for 4 h/d, (RH = 80 ± 5 %) A 3×2 factorial design	Male Gramapriya egg type domestic chickens (India); dietary treatments starting 10 d prior to CyCHS and during CyCHS or for 20 d (Cont. at 30 °C) 1. Cont.; 2. Cont. + Brahma Rasayana extract; Ayurvedic polyherbal preparation in which Emblica officinalis and Terminalia chebula are two major ingredients accounting ≥ 75 % w/w (BR) at 2 g/kg BW	RBC: CAT and SOD activities ↑ by BR vs. respective Cont. Serum, liver: MDA ↓ by BR vs. respective Cont. Liver: CAT, SOD, GSH-Px, GR activities ↑ by BR vs. respective Cont.	[44]
At d 10 of age for 32 d were exposed to: 1. Cont. at 22 °C 2. CyCHS at 34 °C for 8 h/d A 2×3 factorial design	Japanese quails; dietary treatments starting at d 10 of age 1. Cont.; 2. Cont. + epigallocatechin-3-gallate (EGCG) at 200 mg/kg; 3. Cont. + EGCG at 400 mg/kg	Serum, liver: MDA linear ↓ by EGCG vs. Cont. Serum: vitamins C, E, A ↑ by EGCG vs. Cont.	[70]
At d 0 of age for 41 d were exposed to: 1. Cont. at conventional temperature scheme (only Cont. diet) 2. CoCHS at 34 °C	Ross 308 broilers; dietary treatments starting at d 0 of age 1. Cont., T1; 2. Cont. + vitamin C at 250 mg/kg, T2; 3. Cont. + ethanol extract of propolis (EEP) at 0.5 g/kg, T3; 5. Cont. + EEP at 1 g/kg, T4; 5. Cont. + EEP at 3 g/kg, T5	Plasma: SOD activity ↓ by T2, T3, T4, T5 vs. T1; MDA ↓ by T2, T5 vs. T1; CAT activity ↓ by T5 v. T1; GSH-Px ↑ by T2, T4, T5 vs. T1 Liver: MDA ↓ by T5 vs. T1; CAT activity ↓ by T2, T5 v. T1; GSH-Px ↑ by T2, T3, T4, T5 vs. T1 Muscle: MDA ↓ by T4, T5 vs. T1; GSH ↓ by T2, T4, T5 v. T1 Kidney: CAT activity ↓ by T2, T5 v. T1; GSH ↓ by T4 v. T1; GSH-Px ↑ by T2, T3, T4, T5 vs. T1 Heart: CAT activity ↓ by T5 v. T1; GSH ↓ by T5 v. T1; GSH-Px ↑ by T2, T3, T4, T5 vs. T1	[38]
At d 18 of age for 27 d were exposed to: 1. Cont. at 26 ± 2 °C 2. CyCHS at 38 ± 2 °C for 6 h/d On d 1, 7, 14, 21 after starting HS birds were sampled	Male broilers; dietary treatments starting at d 18 of age 1. Cont., T1; 2. Cont. + polyphenols extracted from Tamarindus indica seed coat (PTSCE) at 100 mg/kg, T2; 3. Cont. + PTSCE at 200 mg/kg, T3; 4. Cont. + PTSCE at 300 mg/kg, T4; 5. Cont. + PTSCE at 400 mg/kg, T5; 6. Cont. + PTSCE at 500 mg/kg, T6	Serum: MDA ↓ by T5 v. T1 at d 1; MDA ↑ by T2, T3 vs. T1 at d 7 Serum (in average): MDA ↑ by T2 vs. T1	[68]
At d 0 for 42 d all groups were exposed to CoCHS at 32.86 ± 0.68 °C On d 21 and 42 after starting HS birds were sampled	Cobb broilers; dietary treatments starting at d 0 of age 1. Cont., T1; 2. Cont. + polyherbal mix Stresroak (fruits and leaves from different herbs, containing vitamin C and flavonoids as major active principles) at 1 g/kg, T2; 3. Cont. + vitamin C at 100 mg/kg, T3	Serum: SOD activity ↑ by T2, T3 vs. T1 at d 21; SOD activity ↑ by T2 vs. T1 at d 42; GR activity ↑ by T2, T3 vs. T1 at d 21 and 42	[66]
At d 35 for 12 wk were exposed to: 1. Cont. at 22 °C 2. CyCHS at 34 °C for 8 h/d A 2×3 factorial design	Female Japanese quails; dietary treatments starting at d 35 of age 1. Cont.; 2. Cont. + epigallocatechin-3-gallate (EGCG) at 200 mg/kg; 3. Cont. + EGCG at 400 mg/kg	Liver: MDA, NF-kB linear ↓ by EGCG vs. Cont.; CAT, SOD, GSH-Px activity, Nrf2 inear ↑ by EGCG vs. Cont	[29]
At d 35 for 12 wk were exposed to: 1. Cont. at 22 °C 2. CyCHS at 34 °C for 8 h/d A 2×3 factorial design	Female Japanese quails; dietary treatments starting at d 35 of age 1. Cont.; 2. Cont. + tomato powder (TP) at 25 g/kg; 3. Cont. + TP at 50 g/kg	Liver: MDA, NF-kB linear ↓ by TP vs. Cont.; CAT, SOD, GSH-Px activity, Nrf2 inear ↑ by TP vs. Cont	[71]
At d 35 for 12 wk were exposed to: 1. Cont. at 22 °C 2. CyCHS at 34 °C for 8 h/d A 2×3 factorial design	Female Japanese quails; dietary treatments starting at d 35 of age 1. Cont.; 2. Cont. + Berberis vulgaris root extract (BVE) at 200 mg/kg; 3. Cont. + BVE at 400 mg/kg	Liver: MDA, HSP70, NF-kB linear ↓ by EGCG vs. Cont.; CAT, SOD, GSH-Px activity, HO-1, Nrf2 linear ↑ by EGCG vs. Cont	[72]
At d19 for 5 d were exposed to: 1. Cont. at 24 °C 2. CoCHS at 34 °C (RH = 55 %) A 2×4 factorial design	Ross 308 broilers; dietary treatments starting at d 0 of age 1. Cont., T1; 2. Cont. + cashew nut shell liquid (CNSL, 75 % anacardic acids) at 2 mg/kg, T2; 3. Cont. + grape seed extract (GSE, 40 % proanthocyanidins) at 40 mg/kg, T3; 4. Cont. + electrolysed reduced water (ERW, pH 8.1 to 10.1; Eh -160 to -607 mV), T4	Pectorial superficialis muscle: H2O2 ↓ by T3 vs. T1	[47]
At d 28 for 10 d all groups were exposed to CyCHS at 34 °C for 5 h/d followed by 22 °C, (RH = 50 %)	Ross 308 broilers; dietary treatments starting at d 25 of age 1. Cont., T1; 2. Cont. + Curcuma xanthorrhiza essential oil (CXEO) at 200 mg/kg, T2; 3. Cont. + CXEO at 400 mg/kg, T3; 4. Cont. + lemon peel extract (LPE) at 200 mg/kg, T4; 5. Cont. + LPE at 400 mg/kg, T5; 2. Cont. + orange peel extract (OPE) at 200 mg/kg, T6; 3. Cont. + OPE at 400 mg/kg, T7	RBC: GSH-Px activity ↑ by T2, T3, T7 vs. T1; SOD activity ↑ in T3 vs. T1	[78]
At d 42 for 15 d were exposed to: 1. Cont. at 24 ± 2 °C (only Cont.diet) 2. CyCHS at 37 ± 2 °C for 8 h/d followed by 24 ± 2 °C	Female Xuefeng black-boned chickens; dietary treatments starting at d 42 of age 1. Cont.; 2. Cont. + 200 mg/kg resveratrol; 3. Cont. + 400 mg/kg resveratrol; 4. Cont. + 600 mg/kg resveratrol	Serum: MDA linear ↓; GSH linear ↑; GSH-Px, SOD and CAT activity quadratic ↑; all resveratrol vs. Cont. Bursa of Fabricius: HSP27 mRNA levels linear ↓; HSP70 and HSP90 mRNA levels quadratic ↓; all resveratrol vs. Cont. Thymus: HSP27and HSP90 mRNA levels linear ↑; HSP70 mRNA levels linear ↓; all resveratrol vs. Cont. Spleen: HSP27, HSP70 and HSP90 mRNA levels quadratic ↓; all resveratrol vs. Cont.	[74]
At d 14 for 26 d all groups were exposed to CyCHS at 32 ± 2 °C for 8 h/d followed by 19-24 °C On d 21 after starting HS birds were sampled	Cobb 500 male broilers; dietary treatments starting at d 0 of age 1. Cont., T1; 2. Cont. + 100 mg/kg vitamin E, T2; 3. Cont. + 7.5 mg/kg ginger root powder (GRP), T3; 4. Cont. + 15 mg/kg GRP, T4; 5. Cont. + 75 mg/kg ginger essential oil (GEO), T5; 6. Cont. + 150 mg/kg GEO, T6	RBC: SOD activity ↓ by T5 + T6 vs. T1 Serum: Total antioxidant capacity ↑ by T2, T3, T4, T5, T6 vs. T1; MDA ↓ by T2, T3, T4, T5, T6 vs. T1 Liver: SOD activity ↑ by T5 + T6 vs. T1; MDA ↓ by T3, T4, T5, T6 vs. T1	[75]
At d 28 for 14 d all groups were exposed to CyCHS at 34 °C for 5 h/d followed by 22 °C, (RH = 50-60 %) On d 3 and 14 after starting HS birds were sampled	Ross 308 broilers; dietary treatments starting at d 25 of age 1. Cont., T1; 2. Cont. + Curcuma xanthorrhiza essential oil (CXEO) at 200 mg/kg, T2; 3. Cont. + CXEO at 400 mg/kg, T3; 4. Cont. + Oreganum compactum essential oil (OCEO) at 200 mg/kg, T4; 5. Cont. + OCEO at 400 mg/kg, T5	Plasma: MDA ↓ by T3 vs. T1 at d3; ↓ by T2, T3, T4 vs. T1 at d 14 RBC: GSH content ↑ by T2, T3, T4, T5 vs. T1 at d 14 Liver: CAT activity ↑ by T2, T5 vs. T1 at d 14 d; GSH-Px activity ↑ by T2 vs. T1 at d 14; SOD activity ↑ by T3 vs. T1 at d 3; HSP70 mRNA levels ↓ by T5 vs. T1 at d 3 Kidney: SOD activity ↑ by T3, T5 vs. T1; SOD mRNA levels ↑ by T5 vs. T1; HSP70 mRNA levels ↓ by T5 vs. T1 at d 3 Heart: CAT activity ↑ by T3, T5 vs. T1; GSH-Px activity ↑ by T2, T3, T5 vs. T1; SOD activity ↑ by T2, T3 vs. T1; CAT mRNA levels ↑ by T3, T5 vs. T1; SOD mRNA levels ↑ by T3 vs. T1 all at d 3; HSP70 mRNA levels ↓ by T3 vs. T1 at d 14	[79]

RH, relative humidity; MDA, malondialdehyde; GN, genistein; SC, Schisandra chinensis; LL, Ligustrum lucidum; GR, glutathione reductase; DPLM, dry powdered leaves of mint; RBC, red blood cell; GSH, glutathione; CAT, catalase; SOD, superoxide dismutase; FSE, Forsythia suspense extract; TAOC, total antioxidant capacity; BR, Brahma rassayana (made by the mixing extracts from plants); EGCG, epigallocatechin-3-gallate; H₂O₂, hydrogen peroxide; avUCP, avian uncoupling proteins; GSH-Px, glutathione peroxidase; EEP, ethanol extract of propolis; PTSCE, polyphenols extracted from Tamarindus indica seed coat; Nrf2, nuclear factor erythroid 2–related factor 2; GSSG, glutathione disulfide; BVE, Berberis vulgaris root extract; HO-1, haeme oxygenase-1; GST, glutathione-S-transferase; CNSK, cashew nut shell liquid; GSE, grape seed extract; ERW, electrolysed reduced water; CXEO, Curcuma xanthorrhiza essential oil; OCEO, Oreganum compactum essential oil; HSP, heat shock protein; LPE, lemon peel extract; OPE, orange peel extract; GRP, ginger root powder; GEO, ginger essential oil