263 - Efficacy and Safety of a Novel Source of 25-hydroxycholecalciferol in Performance and Tissue Deposition in Growing Pigs

Abstract: This study was conducted to determine the efficacy and safety of a dietary vitamin D source on growth performance and tissue deposition of 25-hydroxycholecalciferol (25OHD3) in growing swine. Dietary treatments were a control with vitamin D3 at NRC recommended concentrations (C) and 3 diets composed of C + increasing inclusions (25, 50, and 250 µg/kg BioD, Huvepharma) of 25OHD3 (C+25; C+50; and C+250 respectively). Pigs (n = 144) were assigned to 24 pens which were allotted to 1 of 4 dietary treatments and fed for 42 d. On d 0, 39, and 63, serum was collected for 25OHD3 concentration determination and individual BW were measured. At d 42, tissues from 48 pigs (12 pigs per treatment) were analyzed for 25OHD3 concentration, blood chemistry and hematology (BCH) analysis was conducted, and 1 femur from each pig was collected for dual-energy X-ray absorptiometry scanning. Data were analyzed with SAS PROC GLIMMIX and means separated at P ≤ 0.05. No differences among treatments were observed for growth performance (P ≥ 0.2239). Serum and tissue 25OHD3 concentrations increased linearly as dietary 25OHD3 inclusion increased (P < 0.0001). Following a 21-d withdrawal period, 25OHD3 serum concentrations decreased to that of or within 2.76 ± 0.89 ng/mL of C-fed pigs (P > 0.0005). All BCH variables measured were similar among treatments (P = 0.0967). At day 42, femurs from C+50 and C+250-fed pigs had the greatest bone mineral content (BMC) and density (BMD; P < 0.0326). Concentrations of 25OHD3 in serum and tissue increased and BMC and BMD were improved as dietary vitamin D supplementation increased, but pig growth performance was unaltered. Absence of gross abnormalities and changes in BCH as well return of circulating 25OHD3 concentrations to that of C-fed pigs following withdrawal indicate this source can safely improve vitamin D status in growing pigs.