At the Trichomoniasis Forum last week in Omaha, much of the discussion centered on standardizing testing protocols and state regulations for testing cattle shipped between or within states. Currently, 22 states have some regulations regarding testing cattle for trichomoniasis or “trich,” but the specifics of those regulations vary. That variation can complicate cattle marketing, particularly for seedstock producers who sell bulls to customers in multiple states. In some cases, transport of purchased bulls can be delayed by several days while the seller arranges for appropriate testing based on the bulls’ destinations.
Discussion points included several specifications that differ between states with trich regulations.
Age for testing
Some states specify that imported bulls over 12 months of age must be tested, others specify up to 24 months. Some participants maintained that older bulls could be verified as virgins and shipped safely without testing. Others argued that more advanced age increases the likelihood a bull has had contact with females, either intentionally or unintentionally.
Duration of test
Some states have required bulls to be shipped within 30 days of testing, others allow up to a 60-day window from the test to the shipping date. There was general agreement among participants that 60 days provides greater flexibility for the seller and can achieve program goals, provided the bulls have no contact with females during that time.
Pooled versus individual samples
Currently, 11 states of 22 with trich regulations allow laboratories to pool samples from up to five bulls for a single PCR test. If the laboratory finds a positive result in a pooled sample, they can go back and test individual samples to identify the infected bull. This reduces the cost of the PCR test to the producer, but with a small decline in accuracy. Representatives from ThermoFisher Scientific, formerly Life Technologies, outlined a recent study, published in the Journal of Veterinary Diagnostic Investigation comparing the sensitivity of pooling trich samples with individual samples. The study, led by Lee Effinger from the Oregon State Department of Agriculture involved five feeder diagnostic labs in different states running there, with the Kansas State Veterinary Diagnostic Laboratory serving as the central study lab and analyzing the same samples. The researchers found pooling at 1:5 missed 4 percent of T. foetus positive samples and 1:3 pooling missed 3.5 percent of positive samples.