U of I: It's bull buying season. How to manage your herd

Be sure to practice sound management of newly purchased bulls

Proper health and nutrition, and then mixing and monitoring your herd, help ensure a good breeding season

BY JOHN B. HALL, PH.D. Extension Beef Specialist, University of Idaho

It’s hard to believe it is bull buying season already. It is always fun and exciting attending sales and looking for the next herd sire. And that new bull is a big investment.

Bull prices in recent years have been strong but reasonable; still, most producers are paying more for bulls than they have in the past. The key to keeping this investment working for the operation for the next three, four or more years is good management of young bulls. BIOSECURITY AND HEALTH

Make sure you know the vaccines the bull has received before you take him home. Get the exact name of the products used and when they were given.

Share this information with your veterinarian and discuss whether any additional vaccines are needed. If another round is recommended, it should be given at least 30 days before the start of the breeding season.

Ideally, new bulls, like all purchased additions to the herd, should be kept away from the existing bull battery and cow herd for three weeks. Most places don’t have the ability to keep bulls from multiple sales separate, so putting all newcomers together is often the only option.

Bulls that get sick and need to be treated should not be mixed with the herd until given the OK by your veterinarian.

ICA ARCHIVE

IMPACT OF POST SALE WEIGHT LOSS ON BULL FERTILITY

CREDIT: BARTH ET AL., 1995

NUTRITION

Most bulls have been developed on diets that are greater in energy and protein than what typical cow/calf operations feed. In some cases, these bulls may be a little too fat. However, bulls that lose too much weight become infertile.

Canadian researchers retested newly purchased bulls for fertility immediately before the start of the breeding season. In most cases, if bulls lost more than 100 to 150 pounds, their fertility was negatively affected (see chart above).

Remember that young bulls (15-30 months) are still growing. In fact, bulls don’t reach their mature size until they are 4 or 5 years old. So the strategy is

not to have young bulls lose weight, but rather to determine whether they need to continue growing at a moderate rate or a slow rate.

First, assess the bull’s body condition when you get him home. Is his body condition score 5 or 6? Then he is just fine but needs to continue to grow at 1.5-1.75 pounds per day. If he is at 7 or more, he needs to drop a little fat before the breeding season. He still needs to grow, but more slowly, at 0.51 pound per day.

For young bulls to grow at 1.5-1.75 pounds per day, they need a diet that is 11% to 12% crude protein and 60% total digestible nutrients (TDN). A typical Idaho diet for these bulls would be free choice, good-quality alfalfa hay with 3 to 5 pounds of corn, barley, corn gluten feed or wheat middlings (or a similar range cube/cow cake).

Be careful when feeding barley and alfalfa hay, as this combination can sometimes cause bloat. If grass hay is used, then a higher-protein supplement is needed, such as distillers grain cubes or corn gluten feed. The feeding rate is still 3-5 pounds. If you want to limit feed hay to reduce waste, offer hay at 2.2% to 2.5 % of body weight. For a young bull weighing 1,500 pounds, that means 33 to 35 pounds of hay per day.

For a slower growth rate, the diet needs to be 11% crude protein and 53% to 55% TDN. The type and amount of hay offered will be similar to the diets for higher gain, but supplement would be provided only at 1-3 pounds per day.

Check with your Extension professional or consulting nutritionist for custom diets based on hay from your ranch.

GENERAL MANAGEMENT

Young bulls need to be fed separately from mature bulls. Mature bulls don’t need the extra supplement and will force younger, smaller bulls away from needed feed. Provide 3 feet of bunk space per bull so all young bulls get their share.

During the breeding season, young bulls ideally would be put with their own group of cows, separate from the mature bulls. However, the reality of most operations that use multisire breeding groups is that separation of young bulls is an untenable luxury. Mixing young bulls with older bulls about two weeks before the start of breeding season allows them to establish a hierarchy.

There should be enough space when mixing bulls so that the young bulls can get away from older bulls. Putting young bulls with mature bulls is like the high school football team playing against a team of college seniors – there is a greater probability that the young bulls may get hurt.

Young bulls don’t have the breeding capacity and breeding savvy of mature bulls. Young bulls do not produce and store as many sperm cells as older bulls. In addition, young bulls tend to service receptive cows multiple times, as opposed to two or three services for mature bulls.

A rule of thumb for the ratio of cows to a young bull is one cow for every month of age of the bull, up to 30 months. So ideally, two 18-monthold bulls would have only 36 cows to breed. In multiage sire groups, a good management strategy is to rotate or pull young bulls every 30 days. This prevents young bulls from losing too much weight and becoming exhausted.

IS THE BULL PERFORMING?

Breeding soundness exams do not guarantee that bulls will be successful breeders. These exams indicate that there are no problems with observed semen quality and motility, accessory glands, penis structure or physical ability. But the breeding soundness exam does not measure libido, ability to find females in heat or mating performance.

Young bulls should be observed during the first five days of the breeding season. They should be able to find cows that are in heat and successfully mount and service cows. The monitoring is time well spent. Finding bulls that aren’t doing their job and replacing them early in the breeding season will avoid the pain of open cows at pregnancy check.

Enjoy the bull sales. Here’s hoping that you find the bull you need, and that he sires lots of calves and stays in the herd a long time.