PSVIII-1 Hy-D Increases Ca, P and Serum Metabolites Related to Growth in Grazing Animals Receiving a P Deficient Supplement

Abstract

Abstract The aim with this trial was to evaluate the effects of 25-OH Vit D3 in serum metabolites of growing grazing Nellore young bulls during the rainy season with two different supplementary P levels. Two independent and sequential trials were performed: first one using a 250 g/kg CP supplement containing 8 g/kg of P, and the second one using the same 25% CP supplement, with no addition of P. In each trial, eighteen young bulls of 385 kg BW and 18 months of age were randomly assigned to the two treatments (n=9 animals/treatment): addition or not (control) of 25-OH Vit D3 (ROVIMIX Hy-D 1.25%, Hy-D) to the supplement. Animals were placed in a paddock of B. brizantha, cv. Marandú, equipped with electronic feeders that provided individual access (animal/treatment). On day 31 of each trial, blood samples were taken for determination of 25-OH Vit D3, IGF-1, Ca, P, Alkaline Phosphatase (ALP), and osteocalcin (OCa). In each trial, data were analyzed according to a complete randomized design. In the first trial (8 g/kg of P in supplement) the use of Hy-D (Control vs Hy-D) increased serum concentrations of 25-OH Vit D3 (25.8 vs 30.0 ng/mL, P< 0.03); not affecting the others variables. In the second trial, when no P was not added to the supplement, the use of Hy-D (Control vs Hy-D) increased serum concentrations of 25-OH Vit D3 (25.4 vs 44.7 ng/mL, P< 0.01); Ca (10.8 vs 11.3 mg/dL, P< 0.07); P (7.4 vs 8.3 mg/dL, P< 0.08); ALP (205 vs 263 U/L, P< 0.04); IGF-1 (256 vs 327 ng/mL, P< 0.07); and did not affect OCa (P< 0.27). These results showed that positive effects of Hy-D on metabolism could be dependent of dietary P level, with Hy-D being able to maintain the levels of Ca, P and serum metabolites related to growth when no P was supplied in the supplement.