Harlan Ritchie, distinguished professor of animal science at Michigan State University, reminds producers to pay attention to young bulls this winter.

“After the breeding season, young bulls are frequently overlooked in our haste to get ready for the next calving season. Coming 2- and 3-year-old bulls still have a significant amount of growing to do before they are fully mature. Improper nutrition during the winter can be the cause of poor performance the following breeding season,” he cautions.

He says that it is not uncommon for yearling bulls to lose 100 to 300 pounds during their first breeding season. In addition to gaining this weight back during a 9-month fall/winter rest period, the bull must gain approximately 300 to 400 pounds so that he weighs 75 percent of his potential mature weight by the time he is 2 years old. This means he should gain about 2 pounds per day during this period.

Dr. Ritchie notes that depending upon his initial body- weight and condition score, this can be done by feeding 8 to 12 pounds of grain per day plus a full feed of forage—either hay or pasture—and a salt/mineral mix with about 8 percent phosphorus, adequately balanced to meet trace-element requirements.

As a rough guideline, a thin yearling, coming 2-year-old bull can consume 26 to 30 pounds of dry matter per day, which is equivalent to 30 to 34 pounds of air-dry feed. The total diet should contain 10 percent crude protein. If the forage is of low quality, some additional protein as well as vitamin A may be required.

Two-year-old bulls need to gain about 1 pound per day from one breeding season to the next. This can be achieved by a full feed of forage plus grain as needed according to body-condition score. Moderate-framed, easy-fleshing, 2-year-old bulls can often get by on a full feed of medium-quality forage.

“Neither yearlings nor 2-year-old bulls should go into their next breeding season under a BCS of 6 (on a 1-10 scale),” he says. “Mature bulls should have a minimum BCS of 5.”