by Keith Martin
Parsons, Kansas —
One of the most important factors in determining the profitability of a beef herd is the number of calves weaned per cow exposed.
A breeding soundness evaluation of bulls ensures that bulls are capable of settling cows. The ideal time for your veterinarian to conduct an evaluation is about ninety days prior to the start of the breeding season, which for many spring calving herds in our area is now.
In addition to passing a breeding soundness evaluation bulls also need to be in a body condition score of about 6.0 (smooth, no ribs or vertebrae visible) prior to turnout as well. Bulls that are too thin may not have the necessary energy and drive to cover all females that are in heat. Bulls that are on diets low in protein and vitamin A may also have decreased sperm production.
Additional feed should be provided to make sure that bulls are in adequate, but not excessive, body condition at the time of bull turnout.
Also, the bulls’ conformation and potential ability to travel over the terrain and find females in heat should be evaluated. If feet or leg problems exist, affected bulls should be examined closely to determine if the problem is temporary or something that will affect their ability to travel. If the problem has potential long-term consequences, plans should be made to replace bull not up to capable of settling cows.
Preferably 90 days prior to bull turnout, all bulls should be vaccinated to match the cows in the herd (with the obvious exception being no brucellosis [Bangs] vaccine!). This timing will reduce the chance that any vaccines will affect the production of sperm, which begins 61 days prior to the time the sperm is completely matured.
Around 60 days prior to bull turnout, bulls should be evaluated for breeding soundness by your veterinarian. The exam should consist of a physical exam including evaluating the general body condition, feet, legs, eyes and the teeth on older bulls. Assuming the bull passes his physical exam, the reproductive tract should be examined next, including the penis, prepuce and internal reproductive organs which can only be evaluated by rectal examination. Assuming the bull passes the reproductive tract exam, a semen sample should then be collected for an on-site microscopic evaluation. The semen evaluation allows the veterinarian to check the volume, concentration, motility and morphology of the individual sperm cells.
At any step of the BSE process, a bull may be failed or designated for a retest because there is something detected that suggests he might not be a satisfactory potential breeder. In studies with large numbers of bulls, ten percent of mature bulls tested fail this exam.
A relatively new problem that should be tested for on bulls that have previously bred cows it a test for trichomoniasis (Trich). Do this while the bull is still in the chute but after the semen evaluation has been completed and the bull has passed the total BSE..
Trich testing is something new that should be considered for all “experienced”, non-virgin bulls. Virgin bulls that have never been exposed to a breeding-age female will not be carrying this organism and do not need to be tested. However, “experienced” or non-virgin bulls of any age may potentially be carriers of Trich.
Trich has been diagnosed sporadically through the years by the Kansas State Veterinary Diagnostic Lab-oratory, but the disease has been increasingly diagnosed during recent years. More bull owners and sellers have started testing for Trich since the new import regulations were put in place in September, 2010, and several more herds have recently had Trich diagnosed after experiencing infertility problems and low calf crop percentages.
Some herds have been spared the devastating effects of Trich by incorporating testing for this sexually-transmitted disease at the time of routine BSE testing of their experienced bulls.
Talk with your veterinarian about the risk factors you face that might make Trich testing a good thing for your bulls this year. It is always better to find any positive bulls on pre-breeding evaluations than finding out they had it after the breeding season ended!
For information about this and other livestock and forage topics contact the K–State Research & Extension, Wildcat District office at (620) 784-5337 or email me at firstname.lastname@example.org Check out our webpage www.wi ldcatdistrict.ksu.edu for information about the other services available through Wildcat Extension District. £