The Cow-Calf Manager

Livestock Update, November 2004

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

Winterize Your Bull
For most of us, the bulls in our herd are like my 1958 35 hp Evinrude that powers my underused fishing boat. I let the motor just sit there most of the year, but expect it to start on the second pull! Most of the year the bull is "off-duty" and largely ignored, but during the breeding season we expect him to get all the cows bred. Routine bull management is part of a good reproductive management program. No matter whether your herd is a fall-calving or spring-calving herd it pays to winterize your bull.

Physical evaluation
All bulls should be physically evaluated each fall. Examine feet, legs, eyes, body condition, external reproductive structures, and mobility of each bull. This is most easily done in a corral with good solid base or close-up in the pasture, but the bulls donšt have to be run down the chute.

Feet, legs and mobility. It is important that bulls go into winter on a sound set of feet and legs. Winter time usually means poor footing conditions due to ice, mud or snow. Bulls with poor feet and legs are much more likely to be injured during the winter. Fall breeding bulls need to be able to move around well to find cows in heat and breed successfully.

Bulls with mobility problems due to injury or age need to be considered for culling. As bulls get older and heavier, mobility problems get worse. Elongated toes can be trimmed and help improve bull mobility and decrease leg problems. However, bulls with genetic foot problems such as screw claw should be culled.

Body condition. Bulls should not carry as much condition as cows. Mature bulls during the December-February breeding season should be in BCS 5. Young bulls should start the breeding season BCS 5 or 6. All bulls should not fall below BCS 4 during the breeding season. Bulls not used for breeding until late spring can winter in BCS 6 to cut down on feed requirements, but they need to lose excess fat before the beginning of the breeding season.

External Reproductive Structures. Even during the non-breeding season bulls can accidentally damage their reproductive system. Fighting , infections, and injury by brush or fences can result in damage to the testis, penis or sheath. The testes should be of equal size with no damage to the scrotum. Look for injury to the penis or sheath. Bulls with any indication of problems with external reproductive structures should be examined by a veterinarian before the winter. All bulls in fall calving herds should receive a full breeding soundness exam. Some problems can be treated, but often bulls may need to be culled.

Management during winter
Management for bulls that pass their physical exam should focus on proper nutrition, sufficient exercise, and prevention of injury. Mature bulls, young bulls (<3 yrs of age), and yearling bulls should be penned separately. Bull pens should be relatively large and be established on level to rolling ground. Steep pastures should be avoided. Pens that are too small become mud lots during the Virginia winter. This sets bulls up for leg injury due to mud or rough frozen ground.

Barns or sheds are not necessary but access to windbreaks or woods should be provided. During extremely cold weather, bulls should be provided straw or old hay as bedding even in the pasture. Although rare in Virginia, bulls can suffer from frost bite of the scrotum resulting in decreased fertility.

Mature bulls should be fed good quality first cutting hay. Hay should be available to bulls at all times unless bulls are becoming too fat. Bulls will consume about 2% to 2.2% of their body weight in feed daily. This means bulls will consume 35-45 lbs of feed daily. Young bulls need to continue to gain about 2 lbs per day. Young bulls should receive good quality hay and supplement. Supplements should be fed at 0.5% of body weight (about 8 to 10 lbs per bull per day). Mineral supplements for bulls should be a complete supplement with calcium and phosphorus as well as trace minerals. Copper and selenium levels need to be high.

Bulls should be forced to exercise daily. The easiest way to force bulls to exercise is to put hay as far from the water source as possible. Long pens or fields are ideal to force bulls to stay in shape over the winter.

Young bulls (< 3 years old) should be dewormed and treated for lice and grubs. Mature bulls only need to be treated for lice and grubs. As many organophosphate lice and grub treatments have been removed from the market, the best option for lice and grub treatment for all bulls may be a dewormer that has guaranteed persistent activity against lice. Remember to check with you extension agent for the last day to treat for grubs in you area. In most of Virginia, the last date to treat for grubs is November 15.

Ideally, bulls should be observed daily during the winter. At least once weekly, producers should observe all bulls closely for signs of any problems. Bulls breeding cows during December-February should be observed daily, and a bull with any signs of a problem or lack of interest in cows should be examined immediately. If you are in doubt about the ability of a bull to service cows he should be replaced with another bull. Bulls that are injured or not effectively breeding cows should not be left in the pasture with cows and replacement bulls. Dominate bulls that are not breeding or settling cows may prevent other bulls from breeding cows in heat. Injured bulls may suffer further injury if left with cows or replacement bulls.

All bulls should be re-evaluated for physical problems in late winter or early spring. This is immediately after the breeding season for fall calving herds. Proper winter management of bulls and regular evaluation will enable producers to avoid breeding problems or loss of bull salvage value.

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