Dietary Curcumin, Protexin, and Their Combination Improve Selected Productive, Eggshell, Metabolic, and Endocrine Indicators in Broiler Breeder Hens under Chronic Cyclic Heat Stress

Abstract

Chronic cyclic heat-stress conditions can challenge productive performance and physiological balance in broiler breeder hens, particularly during the laying period. The present experiment evaluated dietary curcumin and Protexin, a multi-strain probiotic, alone or in combination, in Arbor Acres broiler breeder hens from 22 to 35 weeks of age. Three hundred hens were assigned to five treatments with four replicate cages per treatment and 15 hens per cage: thermoneutral control, heat-stress control, heat stress + curcumin at 150 mg/kg feed, heat stress + Protexin at 50 g/ton feed, and heat stress + curcumin + Protexin. The thermoneutral group was maintained at 18–24°C, whereas heat-stress groups were subjected to 34°C for 6 h/day. The cage was considered the experimental unit. Egg production and settable egg percentage, defined as externally normal and crack-free eggs, were recorded daily, and egg-quality traits and blood variables were measured at 35 weeks of age. Compared with the heat-stress control, the combined-supplement group increased egg production from 64.95% to 70.87% and settable egg percentage from 63.91% to 68.11%. However, egg weight decreased from 66.98 to 62.89 g. The combined-supplement group also showed greater eggshell thickness, lower serum triglycerides and aspartate aminotransferase activity, higher estradiol and progesterone concentrations, and a lower heterophil-to-lymphocyte ratio. Interleukin-1β was not significantly affected. Overall, dietary curcumin and Protexin improved selected indicators of productivity, eggshell quality, metabolism, endocrine function, and stress response under the present cyclic heat-stress conditions, with the combined treatment showing favorable responses across several endpoints.