Presentation of bovine TB risk information at the point of purchase

This research project funded by Defra focusses on whether the way that bovine TB (bTB) risk information is presented influences the purchasing habits of cattle farmers. The work suggests that making bTB risk information more salient does change the way that they consider risk mitigation after purchasing and bidding for animals.

The project aimed to recommend how information should be presented at the point of purchase so that it is effective in encouraging purchasing decisions to reflect the risk of cattle being infected with TB. The researchers ran an online simulated auction experiment with 248 farmers in England. Each participant was randomly allocated participants to the control or one of three experimental conditions. The control condition showed the date of the selling herd’s last TB skin test. Experimental conditions also showed:

  • Number of years the selling herd has been officially TB free (OTF)
  • Graphical representation of Animal & Plant Health Agency (APHA) five-point herd risk score (see below)
  • Graphical representation of APHA five-point herd risk score (see below) with testimonials and official guidance

The report found that making bTB risk information more prominent increased the amount participants were willing to pay for post-movement isolation and TB testing. Control participants were willing to pay £11.70 per animal on average, compared to £46.53 where the APHA herd risk score was presented with testimonials and guidance. Only 12% of participants in the latter group were not willing to pay anything at all, compared to four times as many control participants (48%). Conversely, showing bTB risk information decreased willingness to bid on high risk cattle, though when participants did bid, the amount was not decreased.

The findings of this report will support Defra’s future work on the presentation of bTB risk information at the point of purchase. Access the full report on Defra’s science and research project website.

APHA five-point herd risk score

APHA generates a bTB risk score for each cattle herd in England. This risk score system is adapted from methodology developed by Adkin et al (2016). The 1 to 5 score represents the likelihood that the herd will lose its OTF status within the next 12 months (1 being lowest risk, 5 being highest risk). All herds start with one point, and up to three further points are allocated based on TB history:

  • A current TB breakdown results in three points being added
  • Up to three points are added depending on the time since the last TB breakdown was resolved (the more recent the breakdown the more points added)

One extra point is added if the herd has had a high risk cattle movement on in the last three years, defined as a movement originating on a holding with an APHA risk score of 5 at the time of the movement.


A virtual auction was chosen as it allowed the researchers to quantify the effect of changing information presentation without asking them directly what they thought of the information. It aimed to give a more realistic understanding of the effects compared to a traditional survey.

In this experiment the catalogue for their trial arm was shown and they then started the auction. Each animal was shown and the participant had to input the maximum they would have bid, and after this they were then told if they were successful or not in their bids. The report has a full breakdown of the process and shows the images that were seen by participants on screen.

We asked participants, regardless of trial arm, a question on each of the three pieces of bTB risk information that were used (date of last TB test, number of years OTF and APHA five-point herd risk score). These questions assessed whether the participants understood what the pieces of information meant in the context of bTB risk. Comprehension of the date of the last TB test and number of years OTF was over 90% for all participants, but was lower for the APHA five-point herd risk score. The researchers suggest that if Defra is to use this measure in future then colour coding should be used to ensure farmers understand what the score is telling them.