“…Calcium metabolism for eggshell formation is primarily regulated by the active hormone vitamin D 3 metabolite (1,25-dihydroxy vitamin D 3 ; 1,25 (OH) 2 D 3 ). Vitamin D 3 is transported to the liver, where it is converted to 25-hydroxyvitamin D 3 ( 25 (OH)D 3 ), binds to vitamin D binding protein, circulates in the blood, and is taken up by the kidneys, where it is converted to 1,25 (OH) 2 D 3 ( Borges et al, 2004 ; Kuwata et al, 2024 ). Therefore, liver and intestinal damage under chronic heat stress is considered a potential cause of decreased eggshell quality.…”