Terminação de bovinos de corte em pastagem com suplementação de cevada, associada ao uso de modificador orgânico e ivermectina.

Abstract

The present study evaluated the use of provisioning with wet brewer's residue associated with an organic modifier and ivermectin for finishing beef cattle on pasture. The study used a total of 40 uncastrated male zebu-type bulls with a mean age of 24 months and mean weight of 444.6 kg. The study animais were identified, weighed individually, and divided into eight sets, which were assigned randomly to the different treatments. The eight treatments were, that is, provisioned with 10 kg of wet brewer's residue or unprovisioned, injected subcutaneously with 10 ml of organic modifier or not, subcutaneous application of 3.15 g of ivermectin or not. For the experiment, the sets were divided into two groups of 20 animais, and kept in enclosures of 10 ha planted with Brachiaria brizantha cv. Marandú grass, covering a total of 40 ha, with a rotating management system. On the first day of the experiment, the animais were weighed, their feces were collected, and the height of the forage was measured, and samples were collected. This procedure was repeated every 28 days until the 84th and final day of the experiment. The experimental design was totally randomized, with eight treatments arranged in a 2 x 2 x 2 factorial. The data were tested using an analysis of variance, which assessed the interaction between the different factors. When no interaction occurred, the mean values were analyzed separately for each factor. The data were also analyzed using the t test with a 5% significance levei. No significant difference was found in mean weight gain between the provisioned and unprovisioned groups, although there was a significant difference (P<0.05) in the mean daily weight gain (MDG) during the Ist period, when the provisioned animais gained 1.779 kg per day against 1.582 kg/day in the unprovisioned group. During the second period, MDG was higher in the unprovisioned group (0.841 kg/day) in comparison with the provisioned group (0.655 kg/day). In the 3rd period, however, the provisioned group once again had a higher MDG (1.204 kg/day) in comparison with the unprovisioned group (0.875 kg/day). A significant interaction (P<0.05) was also observed between provisioning and the application of ivermectin, with an MDG of 1.326 kg/day in the wormed and provisioned group, but only 1.099 kg/day in the unwormed provisioned group. A significant difference (P<0.05) was also found in the MDG of wormed (1.820 kg/day) and unwormed animais (1.541 kg/day). The results also indicated that the application of an organic modifier did not contribute significantly to weight gain in the cattle in the finishing phase.