25-Hydroxycholecalciferol As an Alternative to Vitamin D3 in Diets with Different Levels of Calcium for Broilers Reared Under Heat Stress

ABSTRACT The objective was to evaluate the effect of dietary 25-hydroxycholecalciferol (25(OH)D3) or vitamin D3 (VitD3) and different total calcium (Ca) levels on the performance, carcass characteristics, blood, enzymatic, and bone biochemistry of broilers reared under heat stress between 1 and 42 days of age. A total of 504 male, Cobb 500, broiler chickens were distributed in a completely randomized design in a 2 × 4 factorial arrangement (VitD3 or 25(OH)D3 × four Ca levels (100, 90, 80 and 70% of the recommendations of Rostagno et al. (2011)), eight treatments, seven replicates and nine broilers per cage. Feed intake and feed conversion ratio did not (p>0.05) vary when levels of Ca were reduced and vitamin D3 sources were supplemented in the diets from 1 to 21 days for broilers chickens. 25 (OH)D3 increased weight gain results (p<0.05). From 1 to 42 d, no differences (p>0.05) were observed on performance, carcass yields and meat quality, bone deposition of Ca and P, and alkaline phosphatase concentration. Higher serum (p<0.05) concentrations of Ca and P were found in broilers fed with 25(OH)D3. The replacement of VitD3 with 25(OH)D3 and the Ca reduction of 30% in diets did not negatively affect performance, carcass characteristics, and Ca and P deposition in the tibia of broilers at 42 days of age, under heat stress.