Effect of different supplementation levels and additives on Nellore steers performance finished on pasture
The effect of different supplementation levels and mainly effects of different additives for beef cattle finished on pasture are not completely known. Therefore, the aim of this research was to detect the effect of different supplementation levels and different additives on Nellore steers performance finished on pasture. Eighty Nelore steers with initial BW 480 ? 18.8 kg were blocked according to their body weight and assigned to 20 paddocks of 1.0 ha each of Panicum Maximum Jacq cv. Tanzania pastures. The experiment was conducted as a randomized complete block with 5 treatments and 89 d. The treatments were: supplementations of 0.5% BW (0.5), 2.0% BW (2.0), 2.0% BW with virginiamycin (2.0VM), 2.0% BW with virginiamycin + monensin (2.0VMMO) and 2.0% BW with virginiamycin + salinomycin (2.0VMSAL), offered daily. To measure the performance and the supplementation adjustment, the animals were weighted (after 16 h of food deprivation) in every period. The data were submitted to analyze the diversification of repeated measures over time in mixed models. All data were analyzed using the MIXED procedure of SAS 9.2 program (SAS, 2008), adopting a level of significance of 10%. In the first period, the ADG was greater for animals fed 2.0 + additives (1.18a). Animals fed 2.0 showed lower ADG (0.47b) and animals fed 0.5 were not different from the other treatments (0.75ab). There was probably some metabolic disorder with animals fed 2.0 without additives. In the second period, the animals fed 2.0VMMO, 2.0VMSAL and 2.0, had greater ADG (1.26a, 1.12ab, 1.16ab, respectively) and animals fed 2VM had lower ADG (1.03b) compared to 2.0VMMO, but not different from animals of 2.0VMSAL and 2.0. Animals fed 0.5 had lower ADG compared to other treatments (0.57c). Finally, in the third period, the animals of 2.0VMMO and 2.0 had greater ADG (1.84a and 1.59ab, respectively). Animals of 2VM and 2.0VMSAL had lower ADG (1.47b and 1.51b, respectively), compared to 2.0VMMO, but not different from 2.0, and animals fed 0.5 had lower ADG compared to other treatments (0.41c). To conclude, supplementation of 2.0% BW is better than 0.5% BW and the best additive is the combination of virginiamycin and monesin for animals finished on pasture.