Late summer high temperatures may reduce bull fertility for several weeks after the weather has moderated. In addition, ask your veterinarian about the need for a trichomoniasis test. If the bulls’ feet need to be trimmed, this would be an excellent opportunity to get that done as well.
Bulls that do not pass a breeding soundness exam will need to be replaced before the start of breeding. Purchase the replacement from a production sale or nearby seedstock producer as soon as possible.
It is advantageous to move the bull to his new environment several weeks before breeding. If the bull has been consuming a high energy, grain-based diet, this will give you time to gradually reduce the grain and increase the forage intake. The rumen will take some time to adjust to the forage-based diet that he will consume during the breeding season. A very sudden, steep decline in energy intake could cause a decrease in bull fertility. Therefore a gradual change over several weeks will produce more positive results.
Bulls that will be placed together in multi-sire breeding pastures should be penned together for several weeks before the breeding season begins. Bulls will establish a social order. This needs to be settled before the first of the breeding season. We would prefer that cows are getting bred during the first part of the breeding season rather than bulls fighting each other.
Bulls are a sizeable investment in most cow-calf operations. Common sense management before the breeding season can give the best possible return on that investment. 
Glenn Selk is an Oklahoma State University emeritus extension animal scientist. This originally appeared in the OSU Cow/Calf Corner newsletter.
