Effect of bambermycins and tylosin on performance of growing-finishing swine.

Five experiments (five different locations) with a total of 1,230 pigs (135 pens) were conducted in Minnesota, Missouri and Indiana to study the effects of supplementary bambermycins (2.2 ppm) and tylosin (44 or 22 ppm) in swine diets. The antibiotics were fed during the growing and finishing periods, and effects on rate of gain and efficiency of feed conversion were measured. A significant improvement in ADG and F:G over the control pigs was observed with the bambermycins treatment. A numerical but nonsignificant improvement in ADG and a significant improvement in F:G over control were observed with the tylosin treatment. The performance was divided into growing and finishing periods. In the growing period, bambermycins and tylosin numerically but nonsignificantly improved ADG and F:G over control pigs. The finishing period response to bambermycins was significantly improved for ADG and F:G. The tylosin finisher response was numerically but nonsignificantly improved for ADG and F:G over negative control. Significant location effects were observed. This result would be expected due to variation in genetic background of the experimental animals and differences in housing, environment and management.