Wednesday, January 05, 2005

New Year Resolutions (2)

Dr. Richard Clifton- Hadley (Veterinary Laboratories Agency) joins John Bourne in our gallery of people (who should know better) who have made a quantum leap of assumption regarding cattle Tb.

Professor Bourne along with his colleague Elaine King of the NFBG have assumed - quite wrongly - that the only reason for the arrival of cattle Tb in previously (assumed) Tb free areas is movement of cattle. We make no apologies for pointing out once more, the parasitic link between badgers and the cattle habitat on which they depend.

When cattle were slaughtered by the million during the carnage of FMD, farmers noted that although the deer stayed on the eerily empty farms, once the cattle went, so did the badgers. No dung pats, placentas, dead lambs (or live ones) no autumn crops to feed on and long, rank grass. They packed their cases and moved out. The setts were empty.

Where did they go? To the nearest farm that had the 'habitat richness' on which they thrive - a cattle farm.

And what did they find there? Resident stripeys who didn't welcome an invasion of 'their' territory and fought to protect it. And an enormous upheaval, often referred to as 'perturbation'.

Chris Cheeseman who runs 'Badger Heaven' in Woodchester Park described perturbation thus:
".....encountering more badgers so the contact rate of the population goes up. Contact rate is an opportunity for disease spread. The idea is that disruptive populations may actually be promoting the spread of disease in badgers. We know that increased movements in the badger population lead to an increase of TB in that population"

With that we would not disagree. A shaken and stirred badger population causes endemic Tb to spread.

After FMD, farmers who had restocked their cattle sheds observed that in time badgers returned to those vacant setts. But what a sorry sight they were. Mauled and scarred, thin and mangy. After a year or so away from their own cattle inspired 'habitat richness', the badgers who came back, either original residents or dispersers from other areas, brought with them - and on a large scale - TB which showed up at the subsequent post restocking Tb test.

The point of this post is to point out (with the greatest respect of course) that things are not always as they can appear. The seminar in September at which Cheeseman alluded to perturbation - and then requested more research in to it - was also the scene of a Dr. Clifton-Hadley's 'observation' re cattle movements.

"20 years ago there were 100 confirmed cases (of TB) a year or less. At that time, I would have said that 80 percent of those could justifiably be put down to badger origin". The situation is now entirely different. Data set on cattle movements are available to us that we have never had before. That shows huge numbers of cattle moving around, especially locally".

With all due respect to Dr. Clifton-Hadley, just because we now have cattle movements logged by CTS and BCMS and he is aware of them, it is an incredibly naive assumption that they did not occur, or occurred less, before the birth of cattle passports.

In fact the so called green lanes which Defra are now investigating from 500 year old maps so that drivers of 4x4's can play in the countryside, are in the most part old 'drovers' roads'. Cattle were shod with leather shoes, and driven from the hills of Wales, Dartmoor, Exmoor and Cumbria firstly to the kinder fattening pastures of the river valleys in the midlands and south, and thence on to London and other big cities. Later they travelled by train, and later still via various livestock markets on lorries. Trade was brisk, bouyant and involved hundreds of thousands of cattle, in several short haul journeys.

Recently it could be argued that as the national herd has shrunk, so cattle movement has declined.
Firstly with BSE and the Over Thirty Month scheme, many farmers selling fat have joined the supermarket fan clubs and sell direct, rearing their cattle from birth to slaughter.
Instead of Dr. Clifton-Hadley's "under 100 herds" under restriction 20 years ago, nearly 5000 are now unable to trade cattle except for direct slaughter.
Auctioneers confirm that over the past 6 years, livestock auctions, the trading places for cattle have declined by up to 60 percent.

And some of us have taken notice of the biosecurity advice given by the great and the good, that in some way keeping a closed herd (those sort of herds which Bourne says do not exist) can protect cattle against Tb.
But have found that having no ON movements for several years has no effect at all on the prevalence of Tb.

2005 could be time for a new research project.
Can Tb be transmitted through the ears?

Work it out!

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