Heat stress significantly hinders broiler output by compromising gut integrity, oxidative balance, and immune function. This study evaluated nano-encapsulated phytogenic compounds (NEP) as a nutritional strategy to alleviate heat stress. Three hundred sixty males of Cobb500 broilers were allocated to a 2×3 factorial design with two ambient temperatures and three dietary treatments (6 replicate pens × 10 birds). Birds received a basal diet supplemented with a conventional phytogenic extract (CPE, 500mg/kg), NEP (250mg/kg), or no supplementation (CON). The phytogenic blend contained curcumin (40%), resveratrol (30%), and quercetin (30%) and the NEP consisted of this blend encapsulated in PEGylated liposomes (80–120nM particle size, >85% encapsulation efficiency). From 22−42 days, birds were exposed to a cyclic heat stress treatment (HS; 38°C, 8h/day) or maintained under thermoneutral conditions (TN; 24°C). In CON birds, HS reduced body weight gain (BWG) and feed intake by 24 and 11%, respectively, and increased the feed-to-gain (F:G) ratio by 16% (P<0.05). Compared with HS-CON, NEP increased BWG (+21%) and improved the F:G ratio (−13%). Under HS, NEP reduced serum interleukin-6 (IL-6; −55%), hepatic malondialdehyde (−50%) and jejunal NF-κB mRNA expression (−2.5-fold), and increased serum IL-10 (+89%), IgA (+114%), IgG (+47%), hepatic superoxide dismutase activity (+46%) and glutathione peroxidase (+90%) activities, and jejunal occludin (+2.4-fold), claudin-1 (+2.3-fold) and Nrf2 (+2.2-fold) mRNA expression (P<0.05).  NEP also increased the villus height/crypt depth ratio (+2-fold) and cecal Lactobacillus counts (+1.43 log₁₀ copies/g) and reduced cecal Escherichia coli counts (−1.20 log₁₀ copies/g). In direct comparisons under HS, NEP produced greater responses than CPE for most variables. These findings indicate that NEP, supplemented at half the CPE inclusion rate, attenuated several heat-stress-induced impairments in broilers. Because each formulation was tested at a single, non-equivalent inclusion level without a carrier-only control and bioavailability was not measured, dose–response, carrier-controlled and pharmacokinetic studies are needed to confirm a dose-sparing effect and the underlying mechanisms.

To Cite This Article: Assiri A, Kabi M, Safaa HM and Abbas AO, 2026. Nano-encapsulated phytogenic compounds modulate gut-liver axis integrity, oxidative balance, and immunological activity in broilers exposed to cyclic heat stress. Pak Vet J, 2026, 46(10): 2381-2392. http://dx.doi.org/10.29261/pakvetj/2026.250