Healthy cattle normally carry many bacterial and viral agents in their respiratory system. When stressed, their immune defenses are overwhelmed and BRD develops. Controlling these stresses is often the most cost effective way to reduce disease since stress and other disease precursors make the animal more susceptible to BRD. Many viral agents only produce mild clinical signs by themselves but can predispose the animal to bacterial infections when combined with stress. A good preconditioning program can help reduce the need for antibiotic treatment of BRD at the feedlot.
A Preconditioning Program:
The risk of calves developing BRD when moved from a cow/calf operation will be reduced if the following preconditioning steps are followed:
1. Vaccinate against the major viruses and bacteria that cause bovine respiratory disease at least 2 weeks before weaning, and boost at least 2 weeks before shipping. Vaccines should include those against infectious bovine rhinotracheitis, bovine respiratory syncytial virus, parainfluenenza 3, bovine viral diarrhea virus, Histophilus somni, and Mannheimia haemolytica.
2. Feed a well-balanced ration, including correct proportions of vitamins and minerals, and ensure that calves are eating from a bunk and drinking water from a trough at least 30 days before shipping.
3. Wean calves at least 30 days before shipping.
4. Castrate and dehorn calves at least 30 days before shipping.
5. Prophylactically treat calves with an anthelmentic for internal parasites and, if needed, treat with pesticides for external parasites at least 14 days before shipping.