The number of animals killed without being stunned has risen sharply under a government exemption for Muslims and Jews from humane slaughter rules.
Almost a quarter of lambs had their throats cut without first being made insensible to pain, according to Food Standards Agency figures for April to June this year.
This was an increase from 2013 when 15 per cent of lambs were killed without being stunned and 10 per cent in 2011. The change has been attributed to an increase in halal slaughter rather than the Jewish shechita method.
The figures also revealed that almost a fifth of chickens are slaughtered without being stunned or after a stun that is too weak to guarantee that they do not feel pain.