I wouldn't worry too much if I were you, the trading standards had to respond to a complaint, irrespective if it was genuine or not, the bloke was just doing his job.....but he obviously couldn't distinguish between animal welfare and public health/nuisance matters and has little idea of a big herd, lol! To me anything over 500 sows is a big herd!
From what you've said, your paperwork is all up to date, the animals are remote from the complainants and you've taken the sensible step of halting the veg delivery which was the object of the complaint so the matter should be closed.
It's a pain when you get 'interfering busybodies' or 'malcontent neighbours' making complaints but thats life. I had a visit in spring last year from the RSPCA, an individual had reported that I was keepng a pony in a concrete yard with no grazing. I invited the officer in and explained that the pony suffered from bad laminitis and couldn't be put on rich spring grass. The officer immediately said 'I wondered if that was the case, your perfectly correct keeping her off grass'. He saw that the pony was well fed and cared for and was perfectly happy and departed. I wouldn't have minded but I'm sure the complainant was an individual that habitually parked his car in a layby opposite every weekday morning to walk his dog down the verge letting it defecate everywhere without picking up after it! Grrrr!