Effects of Dietary Microencapsulated Ctx(Ile21)-Ha on Egg Quality and Physiological Responses in Laying Hens Subjected to Heat Stress

This exploratory proof-of-concept study evaluated the physiological tolerability and performance of laying hens fed the microencapsulated antimicrobial peptide Ctx(Ile21)-Ha under severe heat stress (34.5 °C; THI = 85.3). Eighteen 40-week-old hens were evaluated in a 2 × 3 factorial design comprising two thermal environments (comfort: 26 °C; heat stress: 35 °C) and three peptide doses (0.0, 2.5, and 5.0 mg/kg feed). The peptide was synthesized (>95% purity) and microencapsulated by ionotropic gelation, exhibiting controlled in vitro intestinal release. Heat stress significantly reduced feed intake and egg weight (p < 0.05) while increasing rectal temperature (p < 0.01), consistent with a biologically relevant thermal challenge. No temperature × dose interactions were observed for feed intake, egg weight, feed conversion, Haugh unit, albumen height, or blood biochemical parameters (p > 0.05). However, significant interactions were detected for eggshell quality parameters (p < 0.05). In conclusion, while dietary Ctx(Ile21)-Ha did not mitigate performance losses induced by heat stress, the absence of blood biochemical alterations supports its preliminary physiological tolerability under these experimental conditions. Due to the limited sample size (n = 3), these exploratory findings require cautious interpretation.