The ASA has fired a broadside at the Organic Trade Board for suggesting that all organic farm animals are raised to higher-welfare standards than conventionally farmed animals.

The advertising watchdog investigated an ad that was run as part of the OTB's EU-funded three-year generic organic campaign. The ad showed a man and his son dressed as a pantomime cow, headed: "We love organic because we care about animals." Text below the ad claimed 'organic' meant fewer drugs or antibiotics and better conditions for animals.

After considering evidence from the OTB, the ASA concluded the ad was misleading. "We considered that the claim suggested that in all cases, organically farmed animals experienced better animal welfare compared with non-organically farmed animals." It ruled that the ad must not appear again in its current form.

The OTB said the ad had been approved by the Committee of Advertising Practice and Defra, and when the complaint was originally investigated it was not upheld. "We are mystified that the ASA Council overruled the ­advice of its own expert staff," it said.

The ruling is the latest setback to the organic industry's struggle to succinctly communicate what 'organic' means. A 2009 report by the FSA concluded there was no proof that organic food was healthier than conventional food.