Feed supplementation with the Ctx(Ile 21 )-Ha antimicrobial peptide associated with heat stress affects laying hens’ productive performance and physiology

This study evaluated the effects of the supplementation of the antimicrobial peptide Ctx(Ile ²¹ )-Ha in laying hens under heat stress. A completely randomized design with a 2 × 3 factorial arrangement was used to evaluate two thermal environments (Comfort: 26°C and Heat stress: 35°C) and three peptide dosages (D1: 0.0mg/kg, D1: 2.5mg/kg and D2: 5.0mg/kg of feed). The peptide was synthesized by solid phase peptide synthesis, reaching 77.14% of efficiency, with purity degree > 95%. Microencapsulation via ionotropic gelation showed efficiencies of 79.84% (for 100 mg of peptide) and 58.47% (for 200 mg), with in vitro assays confirming controlled intestinal release. Eighteen 40-week-old hens were housed in climate-controlled chambers and supplemented with the antimicrobial peptide. The ingestion of microcapsules was 100% for D1 under both conditions and D2 under heat stress, but only 63.2% for D2 under comfort. Hens receiving 5.0 mg/kg of feed (D2) showed reduced feed intake, especially under heat stress, and slight weight loss, although egg production remained stable. Declines in eggshell quality were observed. Blood analyses showed no significant differences in glucose, hemoglobin, erythrocytes, proteins, or electrolytes for the different peptide doses tested. In conclusion, peptide did not significantly improve egg production or quality. Although no major physiological or productive changes were observed, this study contributes to the development of more sustainable poultry farming strategies.