Incidence of bovine TB on organic farms

Cattle raised on organic farms are susceptible to bovine TB and incidences match, and can even exceed, those on conventional farms. This is supported by data received in emails in 2010 supplied by different ministeries. DAFF in the Irish Republic sent data⁵ for 2009 and DARDNI in Northern Ireland sent details of a study⁴ submitted to the Scottish Agricultural College in 2009.

In Soil Association General FAQs¹ it asks "How does an organic dairy cow's life differ from a non organic dairy cow? Answer: Organic farmers believe that stress is one of the primary causes of disease and welfare problems in intensive livestock farming. The Soil Association standards for organic farming are designed to reduce stress to farmed livestock through a variety of management techniques."

A Soil Association briefing² titled "A sustainable strategy for tackling TB in cattle and badgers" which was prepared in advance of the Defra committee meeting of 24 October, 2007 said the following. "TB in cattle or badgers, as in humans tends (but not exclusively) to affect stressed animals with suppressed immune systems"

In comments from the viewing public for the The Guardian News article³ titled "Badger cull plans for England unveiled" which was published on 15 Sep 2010, the comment which received the largest number of recommendations (in fact 215 recommendations), stated the following "The problem with bovine TB is not badgers but the practise of intensively raising cattle. Go organic, have less stock and have a healthy TB free farm.".

In the Irish Republic on 31 December 2009 there were 972 organic herds recorded on DAFF records of which 45 were disclosed as reactors. This is 4.6%. The number of herds in the country at this time were 117,287 of which 3,222 were reactor herds. This is 2.7%. Evidently these details, which were all supplied in an email from the ministry in the Irish Republic, do not support the widely held view expressed above. The request for this information and the received reply is shown below.

Ireland

Request (Sent 15Sep10)

Reply (Received 30Sep10)

Furthermore the ministry in Northern Ireland (DARDNI) reported⁴ the following.

"Further to my letter to you of 5 October 2010 and discussion with my colleague, I can confirm the position already outlined to you and provide you with some additional information.

A study of the prevalence of Mycobacterium bovis infection in organic livestock herds in Northern Ireland for 2007 and 2008 and case studies of seven herds in a high-prevalence area from 1990 to 2008 was conducted by Olwen M Kerr, BMV&S (Edinburgh), MRCVS. This was submitted to the Environmental Teaching Group, Scottish Agricultural College in 2009 in partial fulfillment of the requirements for the degree of Master of Science.

This observational, retrospective study, which focused on the prevalence of TB on 48 NI organic livestock farms in 2007 and 2008, found no significant difference with that in non-organic herds within their 3 km zones and with the NI prevalence rates.

Case studies of 7 NI organic farms in a high prevalence area from 1990 to 2008, covering both their conventional and organic management eras, found no significant difference between the within-herd animal incidence rates for the 2 management eras or with the area animal incidence rates.

A farm management survey of the case study farms identified changes to management and husbandry practices between the 2 eras which were in common across the studied farms. The results from this study suggest that organic herds, in areas of high TB prevalence, will struggle to escape from the background of infection even when management and husbandry practices are employed which should enhance bio-security.".

Evidently neither the data from the Irish Republic nor the assessment carried out in Northern Ireland support the view expressed above that going organic and having less stock will result in a healthy TB free farm. In fact the data suggests that farming organically makes no significant difference to the susceptibility to the disease and may even put the herd at higher risk.

References

1. Soil Association_General FAQs
2. Soil Association_A sustainable strategy for tackling TB in cattle and badgers
3. Guardian News and Media_Badger cull plans for England unveiled
4. DARDNI_Bovine TB and organic farming
5. DAFF_TB herds on organic farms