Classic and Non-Classic Effects of the Duration of Supplementation of 25-Hydroxicholecalciferol in Broiler Chicken Diets.

The present study aimed to determine the effect of different times of supplementation of 25-hydroxycholecalciferol (25(OH)D) in broiler chickens on the performance, carcass and cuts yield, bone resistance, plasma concentration of 25(OH)D, and expression of the mTOR gene. The treatments were a control diet (CD) supplemented with 3000 IU vitamin D/kg of feed from 1 to 46 d, or the CD + 2760 IU (69 mcg) of 25(OH)D/kg of feed from 1 to 21 d, from 1 to 35 d, or from 1 to 46 d. The period of supplementation of 25(OH)D did not affect the growth performance of broilers, but the breast meat yield was linearly increased in response to increasing days of supplementation ( < 0.05). Birds supplemented with 25(OH)D at the time of the analysis showed an increase ( < 0.05) in the plasma concentration of 25(OH)D when compared to non-supplemented birds. The mTOR gene expression ( < 0.05), and breast protein deposition ( < 0.05) presented a quadratic response related to the supplementation period of 25(OH)D. The fat content of the breast linearly decreased ( < 0.05) as the period of supplementation was extended. The results also showed a positive linear correlation between mTOR expression and 25(OH)D plasma levels (r = 0.593; < 0.05).