27 June 1997

TB threat greatest with high pressure grazing

THE harder cattle are grazed, the more likely they are to pick up TB from pasture contaminated by badgers.

A report published by M R Hutchings and S Harris of Bristol University, and detailed in the Veterinary Record, June 21, 1997 describes the study of the grazing behaviour of cattle on pastures containing active badger latrines. Cattle avoided the latrines until the pasture became depleted, but then grazed them, especially the low ranking animals in the herd.

The report points out that TB bacilli can remain viable in soil for up to two years and may accumulate at active badger latrines, and infect cattle long after badgers have stopped using the latrines.

Chris Cheeseman of the governments badger research unit at Woodchester Park, Glos, is keen to compare farm management practices to demonstrate whether there is a greater risk of spread of TB from badgers to cattle when grazing pressure is high.

"Badgers tend to forage in shorter grass where cattle have grazed," explains Dr Cheeseman. "Moving cattle on, therefore, in a strip or rotational grazing system, would keep cattle one step ahead of the badgers, and could help reduce risks of TB infection. Back fencing could also help keep cattle out of the grazed, shorter grass." &#8226 For more details, turn to p48.n