Email received October 5 2009 from a farmer in Wiltshire
Re the latest e-mail from veterinary surgeon, Hugh Coryn. As a vet he should be aware that if we have damaged the imune system of animals, both farmed and wild, then they will be harder to detect. The skin test for bTB relies on an immune response as the indicator, and all the evidence would suggest that is not the case. He says, "with permanent pastures, little use of fertilisers, rations were very different, no use of pesticides, herd sizes and yields were smaller, housing and management very different, no maize, no forage harvesting - and hay was cut with a knife." The widespread use of pesticides and the transition from hay to silage as a winter feed was well underway in the 50's and 60's. There are still many low input, low yielding herds in the country. Is there any evidence that they are less susceptible to bTB than more intensively managed herds?
Is there evidence that big herds are more susceptible than small ones?
The gradual failure of the bTB testing regime to continue to achieve whai it achieved in the first 3 decades after WW2 coincides with legislation to protect badgers and the introduction of maize (that badgers find very palatable) as a winter feed for cattle. How does he explain that?
(This was in reply to the email from a vet suggesting in the course of so many changes in farming, we may have damaged the immune system of both cattle and badgers.)