LONDON—Britain will offer six-month emergency visas to 800 foreign butchers to avoid a mass pig cull, it said on Thursday, after farmers complained that an exodus of workers from abattoirs and meat processors had left the pork sector fighting for survival. A combination of Brexit and COVID-19 has sparked an exodus of east European workers, leaving some 120,000 pigs in barns and fields across the country waiting to be slaughtered, according to the National Pig Association. Environment Secretary George Eustice said the temporary visas would address the problem which farmers said was putting livelihoods at risk and causing animal welfare issues. “What we’re going to do is allow butchers in abattoirs and meat processors dealing with pigs, to be able to come in on a temporary basis under the Seasonal Worker scheme for up to six months,” Eustice told reporters. “That will help us to deal with the backlog of …