Winter Bull Management

While breeding season may be a ways off, making sure our bulls are cared for throughout the winter and ready to go when it is time to turn out is critical.  A sound and fertile bull can mean the difference between success or failure of next year’s calf crop.  While AI is a valuable tool to use in breeding, across the U.S. 87% of operations still utilize bulls in some capacity. 

Winter care for bulls can be broken down into two categories, body condition and fertility.  Let’s look at body condition first.  Bull condition going into breeding season is a major factor in the success of a bull’s breeding capacity.  In general, a 1:20 ratio of bull to cows is a good starting point, but depending on pasture size, number of herds, and other factors, that number can vary significantly.  However, even with a 1:20 ratio maintained, bull vigor and dominance will also play a role in breeding success. One study noted animals servicing anywhere from 4 to 80 females during the breeding season. 

The energy required to meet the demands of breeding is substantial, and bulls can be expected to lose anywhere from 100 to 400 lbs. during the course of the breeding season.  Getting animals back into condition for next year is one of the primary focuses we should have.  So far this winter especially with a periods of warm temperatures and little snow cover, there has been a great opportunity to build back body condition.  Typically we want animals back to a body condition score 6 before turn out next year.

To do this, take a body condition score now if you haven’t already done so and develop a plan for feeding.  Remember that young animals may not yet be fully grown so will need additional energy and protein to continue growth and build condition.  For this reason, depending on the number of bulls in a herd, separating mature and younger animals into separate herds can make meeting feed requirements for each group easier. 

Meeting mineral requirements is also important.  Research has shown that in particular selenium and zinc are key in maintaining fertility health and sperm production.  Iodine in mineral can help with hoof issues and ensure sound feet going into the breeding season.

The second factor to consider with bulls during the winter is fertility.  Major impacts on fertility in the winter months are cold and frostbite on the scrotum.  Even minor injury can have some impact on fertility, but we really want to protect against major damage that will eventually result in blisters and scabbing.  At this point, sperm production will be impacted.  Spermatogenesis takes up to 61 days, so damage can have long term impact.  Keep an eye out for possible damage when checking bulls and evaluate injured bulls after 45-60 days with a breeding soundness exam.  It’s better to know early that a bull won’t be ready than scrambling for a replacement option last minute.     

To keep cold damage to a minimum, do your best to protect animals from the wind and cold.  Provide plenty of space for animals to find shelter and windbreaks to cut down on wind-chill impacts.  A layer of bedding on the ground helps insulate animals from the cold and protect against freezing. 

While bulls may not be our first focus this time of year, don’t forget to give there care some thought.  Evaluate animal condition and have a plan to get body condition scores back to 6 before next year’s breeding season.  Providing shelter from the cold with windbreaks and bedding will help safeguard fertility and prevent any unwanted surprises later on. 

-Ben Beckman is a beef systems Extension Educator serving the counties of Antelope, Cedar, Knox, Madison and Pierce.  He is based out of the Cedar County Extension office in Hartington.  You can reach him by phone: (402) 254-6821 or email: