Effects of bambermycin with amprolium or monensin on beef cattle growth performance, coccidia infection, and bovine respiratory disease morbidity during receiving

Objective The objectives of this research were to determine the effects of medicated feed additives on performance, health, and coccidia infection in newly received calves classified as high risk for bovine respiratory disease infection. Materials and Methods Growing steers and bulls were received to evaluate the effects of supplying 20 mg/calf bambermycin or 0.77 mg/kg of BW monensin in receiving supplements (20% CP and 78% TDN) compared with a nonmedicated supplement. Fecal samples were collected from 6 steers/pen on d 0, 14, and 28 to evaluate coccidia infection. Water in the bambermycin pens was treated from d 14 to 19 with 10 mg/kg of BW amprolium. Steers remained on treatment for 56 to 84 d for block 1, 49 d for block 2, and 42 d for block 3, depending on availability of wheat forage for subsequent grazing. Results and Discussion There were no differences (P ≤ 0.36) in morbidity, mortality, or animals identified as chronically morbid. Monensin decreased coccidia (P ≤ 0.03) compared with control and bambermycin, which did not differ (P = 0.85). At the end of receiving, BW and ADG for control calves was less than (P ≤ 0.04) for calves receiving bambermycin and monensin. Implications and Applications Monensin or bambermycin can effectively improve BW gain of calves at high risk for bovine respiratory disease. Monensin provides superior control of natural infection of coccidia based on fecal oocyst counts compared with bambermycin. Neither medicated feed additive altered morbidity or mortality due to bovine respiratory disease or treatment response to bovine respiratory disease.