PSVIII-2 - Hy-d Increases Performance of Grazing Nellore Young Bulls Receiving Protein Supplement in the Growing Phase

Abstract: Studies demonstrate the benefits of supplementing 25-OH Vit D3 to bovines, few is known about its effect on performance of grazing animals in tropical conditions. Thus, our objective was to evaluate the effects of inclusion of 25-OH Vit D3 (Rovimix Hy-D 1.25%, Hy-D) in protein supplement on performance of grazing Nellore steers during the rainy season. Nellore steers (n=50; iBW of 346 ± 5 kg; age, 14 mo) were used. Animals were equally distributed in two paddocks (25 animals each one) of B. brizantha, cv. Marandú (7.0 ha each), equipped with electronic feeders, that allowed assess to individual supplement intake. The treatments consisted of a protein supplement (Fosbovi Proteico 30, DSM, Brazil), with or without the addition of Hy-D, in a dose adjusted to daily intake of 1 mg/animal/d. The experimental period was 99-d. To avoid possible effects of paddocks, groups of animals were rotated among the paddocks weekly. At the beginning and at the end of the experiment, animals were weighed after 16h of total fasting. At the end of the trial, blood samples from 15 animals per treatment were collected before fasting, to determine serum concentrations of 25-OH Vit D3. Data were analyzed according to a complete randomized block design. The use of Hy-D (Control vs Hy-D) decreased supplement daily intake (0.753 vs 0.529 kg/d; P< 0.02); did not affected final BW (427 vs 423 kg; P >0.10) or ADG (0.810 vs 0.765 kg/d; P >0.10); and increased the supplementation efficiency (1.166 vs 1.591 kg ADG / kg supplement, P< 0.01) and serum 25-OH Vit D3 (27.3 vs 59.3 ng/mL; P< 0.01). It is known that 25-OH Vit D3 has a positive effect on skeletal muscle hypertrophy and the increased serum 25-OH Vit D3 in the present study points that the greater nutritional efficiency of animal receiving Hy-D could be linked to a greater muscle deposition.