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Virginia Cooperative Extension -
 Knowledge for the CommonWealth

The Cow-Calf Manager

Livestock Update, April 2005

John B. Hall, Extension Animal Scientist, Beef, Virginia Tech

Preparing Bulls for the Breeding Season
Spring is on its way and for spring calving herds breeding season is just around the corner. Often bulls are the forgotten animals in the cow/calf herd. With the activity of calving season, many of the "old boys" are just biding their time in the bull pen or back pasture. Getting bulls ready for the breeding season is like spring training for ball players, the better the training period the more likely they are to complete the season with good numbers.

Management Before the Breeding Season
Young Bulls. Many of you have recently purchased bulls at one of the many bull sales in the state. You made a considerable financial and genetic investment in your herd. However, many of these bulls come out of these sales still in need of additional management and hardening-off before they are ready to breed cows. Bulls from these sales are usually over-conditioned even though they may have been off-test for a month. For example, bulls from the BCIA Bull Test Stations are fed a lower energy ration for about 1 to 1.5 months before sale to start hardening them off. Bulls need to be in body condition score (BCS) 5 or 6 at the start of the breeding season and be physically fit.

Young bulls should be placed on a planned nutrition program. These bulls still need to gain 1.5 to 2 lbs per day while losing their excess condition. In other words, they still need to gain frame, capacity and muscle while losing fat. Bulls should be worked down gradually from their test or post-test diets to their farm diet. Bulls that lose weight too rapidly or crash will have lower fertility and difficulty making it to the end of the breeding season. Get a copy of the diet your new bull was eating at the farm or test station where you purchased him and gradually move towards the farm diet. Some good examples of farm diets for bulls are given in Table 1.

Bulls need lots of exercise to get ready for the breeding season. Bulls that are in good physical shape have higher libido and will have fewer injuries during the breeding season. Although bulls get some exercise fighting and playing with other bulls in their group, forced walking is still needed so bulls will be fit. Placing feed and minerals at one end of a pasture and water at the other end will force bulls to make several trips per day. The bigger or longer the pasture the better.

Young bulls should be kept with bulls their own age and weight. Many young bulls are injured when they are thrown in with other older more dominant bulls. Stifle joint, shoulder and leg injuries are the most common. Bulls that can't walk or mount cows will not get cows bred. Young bulls housed with older bulls just become expensive punching bags.

Table 1. Some Farm Diets for Bulls
Ingredients (lbs per bull per day)
Diet Grass-Legume Hay Grass Hay Corn Soybean meal or 16% protein supplement Corn Gluten Pellets Complete mineral w/ high Se and Vit A
Pre-Breeding Season
Mature Bull
35-20         .3
  35     5 .3
Two Year old Bulls
(1.0 lbs/day gain)
  30     8 .3
35   6 2    
Yearling Bulls
(2.0 lbs./day gain
30       15* .3
  30 12* 2   .3
Breeding Season **
Mature Bull
Pasture replaces hay 6 7 .3
Two Year old Bulls
(1.0lbs/day gain)
Pasture replaces hay 8 8 .3
Yearling Bulls
1200 - 1500 lbs.
(2.0 lbs./day gain)
Pasture replaces hay 12 12 .3
*Grain in excess of 10 lbs should be split into 2 feedings
**Supplements may be difficult to feed during the breeding season; bull condition should be monitored carefully

Most young bulls in Virginia are sold after having passed a breeding soundness exam. However, if your new bull has never had a breeding soundness exam or if it has been longer than 4 months since his exam, he needs to have a breeding soundness exam. Using a bull that hasn't had a breeding soundness exam is like playing roulette. All too often I hear a story from a VA beef producer where he only had a 40 to 50% calf-crop because he didn't have his bull checked. Breeding soundness exams are inexpensive compared to the cost of lost calves. Prices will vary from veterinarian to veterinarian depending on whether he comes to the farm or you bring the bull to the clinic. Generally, the test cost is $30 to $60 not including the farm call charge.

Older Bulls. Older bulls also need to get into physical shape for the breeding season. Mature bulls should be in BCS 5 at the start of the breeding season, and stay in BCS 4 to 5 for the duration of the breeding season. Most are fat after the winter and time off from last breeding season. Some are too thin. Generally, mature bulls just need good quality hay available at all times. The same exercise strategy used for young bulls, with placement of feed and water at opposite ends of the pasture, should be used on older bulls.

All older bulls should have a full breeding soundness exam before each breeding season. Not only will this exam evaluate his reproductive systems, but it will evaluate his feet, legs and eyes as well. Older bulls that have been inactive often need their feet trimmed. If the breeding soundness exam is given 30 to 60 days before the breeding season, then producers have enough time to replace the bull if needed.

Management During the Breeding Season
Both older and young bulls need some basic management during the breeding season to insure a high pregnancy rate in cows. First, they should be observed for the first few days of the breeding season to ensure they are:

  1. Finding cows in heat
  2. Able to mount cows
  3. Able to service cows

Although bulls have passed a breeding soundness exam, they have not been checked for libido (desire to breed) or breeding ability. Older bulls may lose libido and stop breeding cows. Other times, injuries that were not apparent earlier are keeping them from breeding cows. In both low libido and inability to mount situations, bulls need to be replaced. Young bulls sometimes have trouble servicing cows. Some will learn with a little practice, but others never are capable and need to be replaced. It is important that you actually observe bulls servicing cows to confirm their ability to breed.

Bulls should be maintained in single sire groups or in multisire groups of age and size matched bulls. Young bulls placed with older bulls get injured and breed few cows. Research indicates that in multisire breeding groups the dominant bull will breed 60% to 75% of the cows. Even when the dominant bull is infertile, he will often prevent other bulls from mating with cows in heat. So the advantages to multisire groups can be minimal. A better option is to rotate bulls among single sire breeding groups every 3 to 4 weeks.

On most Virginia farms, the ideal cow to bull ratio is 25:1 or 30:1for mature bulls and 15:1 to 20:1 for 15-month-old to 18-month-old bulls. The rule of thumb for young bulls is one cow for every month of age. In managed grazing situations where paddock size is small, mature bulls may be able to handle 40 to 50 cows.

Bulls should be monitored for body condition and injuries. Body condition should be monitored weekly. If bulls fall to BCS 4, they should be supplemented or they should be replaced. Bulls should be seen daily or at least several times per week and checked for injuries. Injured bulls should be replaced immediately. Injured bulls will not get better if they remain with cows so they should be replaced and rested.

Good management of your bulls will pay off. So give the fellas a little extra attention and they'll do a better job with the ladies.

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