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

SIMPLE SUMMARY: Genetic programs of modern commercial-type broiler chickens are based on growth performance parameters associated with muscular growth, feed efficiency, and meat and breast yield. Therefore, highly bioavailable vitamin D(3) to sustain optimal muscle and bone development is necessary. In the present study the effect of different durations of supplementing of 25-hydroxycholecalciferol (25(OH)D(3)) in broiler chickens was evaluated. Growth performance response, carcass and cuts yield, bone resistance, plasma concentration of 25(OH)D(3), and expression of the mTOR gene were evaluated. The use of 25(OH)D(3) in the diets for broilers during different feeding periods did not influence growth performance but increased the plasma concentration of 25(OH)D(3), and increased breast yield as the duration of the supplementation was extended. The supplementation of 25(OH)D(3) increased breast yield and protein deposition in the breast muscle which may have been a result of the epigenetic changes caused by this vitamin D (Vit D) metabolite. ABSTRACT: The present study aimed to determine the effect of different times of supplementation of 25-hydroxycholecalciferol (25(OH)D(3)) in broiler chickens on the performance, carcass and cuts yield, bone resistance, plasma concentration of 25(OH)D(3), and expression of the mTOR gene. The treatments were a control diet (CD) supplemented with 3000 IU vitamin D(3)/kg of feed from 1 to 46 d, or the CD + 2760 IU (69 mcg) of 25(OH)D(3)/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(3) did not affect the growth performance of broilers, but the breast meat yield was linearly increased in response to increasing days of supplementation (p < 0.05). Birds supplemented with 25(OH)D(3) at the time of the analysis showed an increase (p < 0.05) in the plasma concentration of 25(OH)D(3) when compared to non-supplemented birds. The mTOR gene expression (p < 0.05), and breast protein deposition (p < 0.05) presented a quadratic response related to the supplementation period of 25(OH)D(3). The fat content of the breast linearly decreased (p < 0.05) as the period of supplementation was extended. The results also showed a positive linear correlation between mTOR expression and 25(OH)D(3) plasma levels (r = 0.593; p < 0.05).