A genetics company which provided defect bull semen to farmers last year has received a warning from the Commerce Commission about its marketing.
About 900 farmers were affected after they used semen from a bull called Matrix to artificially inseminate their herds.
Matrix, who belonged to Livestock Improvement Corporation (LIC), sired around 6000 calves, of which 1500 heifers were born carrying a genetic defect.
The defect typically caused excessive hairiness and an intolerance to heat, which could affect the animals' ability to produce milk in the future.
A complaint was made to the Commerce Commission in October and the regulator has now served LIC with a compliance advice letter.
The letter states that LIC may have breached the Fair Trading Act by using the term "DNA-proven" in its marketing material to describe Matrix.
"There were a couple of things with their marketing of the product we were concerned about," said a spokesman for Commission.
The term 'DNA-proven' is only accurate when used to describe a bull which has already proven itself through the performance of its daughters.
Matrix was in fact a 'genomic bull' who had been selected on the basis of his ancestry rather than his progeny.
LIC has now re-configured its genomically-selected bull group to include a mix of the two - the best genomically-selected and best daughter-proven bulls in one team, said spokeswoman Clare Bayly.
The wording used to describe these bulls has been changed to the "Forward Pack".
Bayly said LIC had also made a $4.7 million "gesture of goodwill" to farmers who had been early adopters of genomic selection technology.
"In relation to Matrix, LIC is pleased the Commission recognised the work LIC did to isolate and identify the mutation had been done as quickly as possible," she said.
The Commission has advised LIC that it does not intend to take any further action.
Matrix has been culled and although farmers were advised to also cull their affected animals, a number have chosen to grow their animals out for beef.
* The $4.7 million paid by LIC was to early adopters of genomic selection technology, not to cover the costs of semen and inseminations from Matrix, as an earlier version of this story stated.