FORT COLLINS, Colo. — Like any other asset on the farm or ranch, a maintenance check for your bulls before breeding season can prevent some major headaches down the road. There are a few things to ensure before a producer puts the bull battery to work.
Physical condition of a herd bull should be evaluated on two main factors. First, would be the bull’s body condition. Like a cow, a bull in good body condition will be a minimum of a Body Condition Score (BCS) of 5 up to a BCS of 7 with BCS 6 being ideal. Although grazing conditions in spring and early summer may be ideal, a bull can lose 100 to 200 pounds during breeding season from traveling and servicing cows and heifers.1 Providing proper nutrition prior to breeding season to increase or maintain an ideal body condition is best.
Mature bulls will need to be evaluated for there overall size. Bulls continue to grow as they age. Bulls can outgrow and become too big to service females without hurting themselves or the females due to the bull’s excessive weight. It may be time to transition such bulls from use on heifers to utilizing on mature cows, or with current prices you may look at culling and replacing these bulls.
The second factor of physical condition to be evaluated would be focused on the bull’s structure and locomotion. A bull with correct structure, especially in the feet and legs, can travel easily across pastures. Poor structure or injuries can create problems with locomotion and the bull’s ability to travel pastures. A bull with locomotive problems will tend to service less females and graze in a smaller area. Be cautious of bulls with toes that are long, curl or rub against each other as these situations can cause abscesses and eventual lameness just weeks into a breeding season. A bull with minor structural issues may still be able to service females but may need to be reserved for use in pastures that are smaller or easier to travel.
A Breeding Soundness Exam (BSE) with your veterinarian can give you insight into the reproductive readiness of your herd bulls. A BSE includes an evaluation of structure and locomotion, but the focus is on the bull’s reproductive ability. A BSE will include an evaluation of semen quality examining the motility and morphology. To pass a BSE, a bull needs to have a motility above 30% and a morphology of 70% or more normal.2 A measurement of scrotal circumference is taken as well, and the measurement should fall into an acceptable range based on a bull’s age. Bulls who do not meet all the minimums of the BSE could be re-examined at a later date, or if they are deemed unsatisfactory, culled and replaced.
A herd bull should also be up to date on all vaccinations and tests for any contagious diseases. Since a bull travels and comingles with multiple other cattle, ensuring he is not at risk, or the carrier of infectious disease is imperative.
The number of bulls needed to breed a herd should be calculated as well. The basic rule of thumb is a ratio of one female per month of the bull’s age. Bulls are considered mature enough for breeding at around 18 months of age and could then be put with up to 18 females. There is a maximum number of females a bull can service. Mature bulls over 30 months of age, should be put with a maximum of 30 females. This is under ideal pasture breeding conditions. If pastures are large or hard to travel, lowering the bull to female ratio is advisable. It is also advisable to have one or more bulls available, depending on the number of females to be serviced, in case of an injury to a bull who is out on pasture. Injuries can occur from traveling rough pastures, infections like foot rot and of course fighting between bulls. If using single bulls in pastures, it is wise to rotate bulls every 21 days during the breeding season, as injury, sickness or even heat stress can cause bulls to become infertile after turnout.
A bull’s time to service females is short. Having bulls in good condition, structurally sound, and have passed a BSE should give a producer the confidence their bulls will take care of business this breeding season.
–Scott Stinnett, Colorado State University Extension