Combined use of ionophore and virginiamycin on metabolism, digestibility, and feeding behavior of Nellore steers confined with high concentrate diets

Abstract

Increasing concentrate levels in diets for confined beef cattle is a reality in Brazil. However, Nellore cattle, which represents the vast majority of confined animals in this country, may present metabolic disorders due to harmed ruminal fermentation. The inclusion of additives such as ionophores and virginiamycin in confined beef cattle diets has been widely studied and the results show improvement in performance and ruminal fermentation. However, recent studies indicate that the combined use of ionophores and virginiamycin may present better results on animal performance, probably due to more efficient stabilization of ruminal fermentation. Thus, two experiments will be conducted with the objective of verifying the effects of the combination of salinomycin and virginiamycin on ruminal parameters of confined Nellore steers. In the first experiment, the combination of additives will be compared to the individual utilization of additives, by the conduction of two trials in a 4x4 Latin square design, with four rumen-cannulated animals and four periods. In the second experiment, the combination of salinomycin and virginiamycin will be evaluated for two concentrate levels (70 and 90%) by the conduction of two trials in a 4x4 Latin square design (four rumen-cannulated animals and four periods), in a 2x2 factorial, with two levels of concentrate and two levels of virginiamycin. Salinomycin will be added in all treatments. Therefore, it might be possible to settle nutritional recommendations for a secure utilization of high concentrate diets for Nellore cattle.