Bulls are usually purchased from outside sources. Genotype and phenotype are important factors in bull selection, but information about health should also be considered. The following health issues should be considered:
Breeding Soundness Examination (BSE)
BSEs should be completed each year at least three months before breeding season. This leaves time to recheck questionable bulls and locate replacements if necessary.
A BSE is a uniform method of assessing a bull’s likelihood of accomplishing pregnancy in an appropriate number of open, healthy, cycling cows or heifers in a defined breeding season. Bulls can be classified as satisfactory or unsatisfactory potential breeders. A classification of unsatisfactory does not mean a bull is completely sterile but is considered sub-fertile. A sub-fertile bull eventually may get cows pregnant, but he will take longer than a fertile bull to settle a group of cows. The result is that sub-fertile bulls produce fewer calves as well as calves that are born late in the calving season, which are therefore younger and lighter at weaning. The net effect is fewer pounds of beef per exposed cow.
A breeding soundness evaluation does not evaluate a bull’s libido or actual mating ability, nor does it ensure that a bull will remain a satisfactory potential breeder the entire breeding season. If a bull suffers injury to its feet, legs, reproductive tract or other area, such an injury may render it incapable of breeding cows. Therefore, it is important to observe bulls closely throughout the breeding season for libido, mating ability, health and injuries.
For more information on BSEs, see “Bull Breeding Soundness Evaluations” at www.lsuagcenter.com
A preventive herd health plan should always include bulls. A comprehensive plan for bulls should be developed with the herd veterinarian and include purchasing decisions (health status of the herd of origin), vaccinations, deworming and nutrition. Vaccinations are generally the same as for the cow herd, but additional or more frequent vaccinations may be warranted based on the value of the bulls. Bulls are generally more susceptible to parasites, so attention to both internal and external parasite control is crucial.
Any disease that impacts the health of bulls can impact fertility. In the South, heat stress is a major cause of bull infertility and decreased libido. High temperatures, especially combined with high humidity and high nighttime temperatures, are especially detrimental to bull health and fertility. Bos taurus breeds, especially those from northern herds, are more susceptible.
A body condition score of 6 out of 9 is the ideal target prior to the start of breeding season. Body condition can be affected by length of breeding season, number of cows the bull is expected to service, grazing and supplemental feeding conditions, topography (marsh, hills, etc.) and the distance required to travel during breeding.Bulls can be nutritionally classified into one of three categories:
1) Mature bulls in good body condition
2) Mature bulls that need to gain weight
3) Young bulls (2 year olds and yearlings)
Minerals – All bulls should be maintained on a good, balanced mineral program similar to the rest of the herd.