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Brucellosis rules: New cattle testing requirements went into effect in 2017

by Wyoming Livestock Roundup

During their Sept. 15 meeting, the Wyoming Livestock Board (WLSB) passed changes to their Chapter Two rules related to brucellosis testing. The new rules changes the age requirement for all heifers for testing from 18 months of age to 12 months of age.

“We really want producers to understand and know about these changes, so they’ll be ready to comply with them after the first of the year,” said Wyoming State Veterinarian Jim Logan.

The rules were signed into effect by Gov. Matt Mead on Oct. 31 and went into effect on Jan. 1.

Rule clarification

The new Chapter Two rules state that all sexually intact female cattle and bison 12 months of age and over must have a negative brucellosis test within 30 days prior to moving or changing ownership between the dates of Feb. 1 and July 31. From Aug. 1 to Jan. 31, any negative test is valid until the end of the time period.

The rules further clarify the age for testing stating, “Heifers born during the previous calendar year and shipped after Aug. 1 of their yearling year shall be tested for brucellosis.”

Logan says, “The key change is the definition of test-eligible bovinae, which is cattle and bison.”

“The previous definition of test-eligible females were those 18 months of age and over,” he explains. “It also previously included visibly pregnant or post-parturient bovinae. Now, it simply says all sexually intact female cattle 12 months of age and over.”

Impetus for change

The rules were amended following the discovery of brucellosis last fall in a herd in Sublette County.

“We recognized that the old rule did not adequately cover heifers that may have been exposed to a bull during the breeding season and yet might be sold as feeders while less than 18 months of age that could have been a brucellosis transmission risk,” Logan says. “During the epidemiologic investigation of the case in Sublette County, a potential loophole in the rule was identified, so the Board voted to change the rule to include testing any heifer or sexually intact female 12 months of age and over.” 

Taking comments

The rules were out for comment during the summer, and Logan noted that both brand inspectors and producers mentioned that requiring brucellosis tests for yearling heifers was vague, especially when looking at a group of heifers in June or July, wondering whether they are 12 months of age or not.

“The Board decided to include in the section about test requirements that heifers shipped after Aug. 1 of their yearling year shall be tested prior to movement from the DSA or change of ownership,” Logan explains.

Additionally, the validity of the test varies based on date of movement.

“Any brucellosis test between Aug. 1 and Jan. 31 is valid until Jan. 31. From Feb. 1 to July 31, tests have to be done within 30 days for movement or change of ownership,” Logan says, noting that the change of dates relates to the risk of exposure during the elk or bison abortion or calving season.


Logan notes that he does not believe the new test requirements will affect a greater number of producers that were not testing for brucellosis before. However, he believes more cattle will be encompassed in the increased test requirements.

“This change will encompass quite a few more cattle than what were tested before,” he explains. “That leaves me with a little bit of concern about how much more this costs the budget.”

Logan notes that, despite increased costs, the rule change should help to prevent potential brucellosis spread.

Veterinarians who test cattle are compensated five dollars per head, which could impact budgets. Additionally, veterinarians at sale barns are paid, and the sale barn is compensated if they provide the crew to help work cattle.

“Our expenses will probably be slightly higher, but these changes should help to prevent a wreck from occurring,” Logan comments.

Saige Albert, managing editor of the Wyoming Livestock Roundup, and Emilee Gibb, editor, contributed to this article. Send comments to

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