At first glance, the life of the herd bull looks pretty easy.  Work 2-3 months of the year and get the rest of the year for rest and relaxation.  However, things aren’t quite that simple.  The bull’s year should be thought of as three seasons: 1) Pre-breeding and conditioning for at least 2 months; 2) Breeding season for 2-3 months; and 3) Post breeding recovery for 4-8 months.

What often gets missed is the importance of pre-breeding and conditioning.  Sperm development takes at least 60 days on average for bulls.  Major stressors, such as introducing a new bull, poor nutrition, and heat / cold shock, less than 60 days before the start of breeding season can have a negative impact on bull fertility.  Also during the pre-breeding period bulls should physically and nutritionally prepared for the work they have ahead of them.  During the peak of breeding season bulls will need the physical stamina to cover many miles in one day.  Just like with people, reaching this level of fitness won’t happen overnight.  Offering a 1-2 acre lot during the pre-breeding period will go a long ways in building a bull’s stamina.  If you only have one bull for your herd consider providing a companion animal, such as a steer, during this time. 

Ideally bulls should have a similar Body Condition Score (BCS) to that of replacement heifers: from a 5 to 6.5.  Top performing bulls will breed 6 to 8 cows per day.  With this type of workload, weight loss is unavoidable so bulls should be in adequate condition before breeding begins.  Also remember young bulls are still growing and may need extra feed during the breeding season. 

Many factors influence how many females a bull can service during the breeding season.  A basic rule to start with is a bull can service as many females as he is months old.  For example, a yearling bull 14 months old could be run with about 14 females.  A three year old bull could be run with up to 36 females.  Depending again on conditions, 40-50 is the maximum number of females a top performing mature bull should be exposed to at one time.  Smaller herds that only use one herd bull may want to be more conservative with the number of females exposed.  If this single bull becomes too run down or injured from trying to cover too many cows, it could be disastrous for the rest of the breeding season. 

Your herd bulls should be up to date on vaccinations and deworming, just as you would be doing for the cow herd.  Check your bull’s feet and legs for soundness, and if a foot trim is in order try to have it done at least a month before breeding starts.  Finally, consider having a breeding soundness exam performed on your bulls.  A trained technician / veterinarian can analyze your bull’s sperm motility, sperm morphology, scrotal circumference, and a through exam of the bull’s reproductive tract for any abnormalities.  Identifying problems now can save headache and worry from cows being exposed to infertile bulls. 

For more information on preparing your bull for breeding season check out these further resources.

Source: Ryan Sterry, UW Extension Agriculture Agent St. Croix County

Management of Yearling Bulls, Dr. Amy Radunz, University of Wisconsin – Extension.

Don’t Forget About the Bulls, Bethany Lovass DVM, University of Minnesota Beef Team,

Management of Beef Bulls, Glenn Selk, Oklahoma State University,