The two major areas to emphasize for prevention are management and vaccination. Of the two, management is usually much more important.
Management
Evaluate all the possible causes for stress on the cattle, and determine which ones can reasonably be eliminated or at least reduced. Look carefully at alternative methods of operation and at specific timing of processing, vaccinating, etc. Recognize that the critical period for disease detection is the 3 weeks immediately following weaning, placing on feed, or shipping of cattle.
Avoid mixing (comingling) cattle from different sources during this highly critical 3-week period. Preconditioning does reduce the rate of illness and death, but this practice must be evaluated in terms of economic costs and benefits for the specific producer involved. Arrange the pens and feeders to keep new cattle close to the feed and water supplies. Don’t overcrowd, especially early in the feeding period. Control the dust and mud.
Source: Iowa State Ag Extension