All bulls that will be used in a breeding season need to be tested. Without a breeding soundness exam (BSE), producers are taking a huge risk. Breeding Soundness Exams are low-cost and provide a great return on investment. Bulls that are infertile or have poor fertility will fail to settle cows.
Evaluating bulls is crucial to making sure that cows get bred. A BSE should be conducted each year prior to turnout by a veterinarian. Environmental factors, age, and injury can all affect a bull's fertility from year to year.
Bulls should also be evaluated for mobility, body condition score (BCS), age, and other functional traits. Bulls need to possess a free-moving gate with no signs of lameness. Hoof shape, joints, and locomotion speed need to be appraised. Long toes, cracked hooves, or signs of foot rot will be characteristics that can cause lameness and subsequently failure of that bull to service cows. Swollen, fluid-filled joints may be signs of structural incorrectness or injury that may affect the number of cows a bull can cover. Simply looking at the speed and comfort of a bull during locomotion can be valuable in determining his functionability as a walking herdsire.
Bulls need to be in good body condition. Ideally a BCS of 5 or 6. Bulls that are too thin or too fat can pose problems. Bulls will generally lose weight during a breeding season because they are focused on breeding and traveling to service ready-to-breed cows. Thus, it is important to ensure bulls are in good condition. On the other hand, bulls that are too fat may be out of shape and more fatigued when servicing cows. Over-fat bulls are also prone to infertility during hot weather as fat around the scrotum limits cooling and thermoregulation.
Bulls should also be transitioned nutritionally. Feeding bulls a balanced diet in a drylot situation where feed is close and readily available is far different than a big pasture full of cows needing bred. Lush, spring grass is not near as nutrient dense as hay and grain offered in the drylot setting. Thus, transitioning bulls to pasture is important to making sure they don't "melt" or "crash" when they go to pasture to breed cows. I suggest feeding a low protein, high energy supplement at 2-4 pounds per head per day. This is very important if you are using yearling bulls. These bulls will have higher nutrient requirements than mature bulls because they are still growing.
Once bulls are in the pasture or breeding pen, they need monitored for libido. Bulls need to be checked for activity and to make sure they are servicing cows in heat. Sun-up and dusk are good times to check to see if bulls are breeding cows.
Open cows are a major drain on profitability of a cow/calf operation. There is no doubt that reproduction is a sensitive mechanism and is vulnerable to several factors. However, evaluating bulls to ensure they are capable to service cows is the starting point to making sure your breeding season is successful.