Gassing badgers is a "much nicer way" to control them, the Princess Royal has said.
Anne also spoke of her pro-stance on genetically modified (GM) crops, in staunch opposition to that of her brother, the Prince of Wales, who is well known for being anti-GM.
Appearing on the BBC's Countryfile programme, the keen equestrian suggested eating horsemeat is "worth looking at", adding that she has tried eating it and found it tasted "very good".
In a series of discussions on countryside matters, Anne talked of the contentious topic of the recent pilot badger culls, one of which was carried out in Gloucestershire where she lives and farms.
Her remarks led to anger from animal rights campaigners, who argue that gassing - which was banned in 1982 - is inhumane.
An independent report on the pilots found the level of culling needed to bring about a reduction in TB in cattle had not been achieved by "controlled shooting" - the shooting of free-running badgers.
Asked about alternatives to gunning them down, Anne told the programme that most people "will tell you that gas is a much nicer way of doing it, if that's not a silly expression".
She explained: "Because of the way it works. And how it works is that you go to sleep, basically."
Humane Society International UK executive director Mark Jones said: "It is extremely disappointing that a prominent member of the royal family should endorse the gassing of a supposedly protected indigenous wild mammal.
"Gassing experiments carried out at Porton Down in the early 1980s were abandoned because of the appalling levels of suffering to which the badgers were exposed.
"Lethal concentrations of gases in complex badger setts are difficult to achieve, making sub-lethal exposure and associated suffering highly likely.
"Any attempt to reintroduce gassing would doubtless result in a slow and painful death for many badgers, and potentially other non-target animals."
Anne has farmed at her Gatcombe estate for nearly four decades, where bovine TB has wiped out a third of one herd in the past two years.
But she added that the feared spread of TB to cattle was not the only reason to cull badgers, which she said were getting out of control in some areas, causing problems for other species such as hedgehogs, bees and ground-nesting birds.
She told the programme: "Even if you took the cattle completely out of this debate... from a conservation issue alone, you'd have to say there are too many badgers. A bigger growth in the badger population is not good for the balance of conservation anyway."
The Queen's daughter conceded that "t here is no simple answer and some of the answers are difficult and not necessarily comfortable".
"It's a serious business looking after the countryside and it's a much more serious business feeding people," she added.
Asked about her views on GM crops, Anne said: "I think it has a role to play, to be honest.
"I think the claims are probably slightly greater than most of the deliverables actually are. They do add to our ability to perhaps be more efficient users of the land.
"That is good, because I think in the long term, when you've got the prospect of nine billion to feed, you are going to need some help in doing that and to do it well."
She admitted she "seldom" discusses the subject with Charles, who once suggested the method risked creating "the biggest disaster environmentally of all time".
Anne said opponents to GM crops should accept that genetic engineering is inevitable.
She told the programme: "I do think there are some things which, even if you don't like the sound of it yourself, you know that it's got to a point where you're not going to stop it, because you can't.
"So, you really must focus on how you can get the best out of it so it works for humans and the globe in the long run."
Former British eventing champion Anne was also questioned about her comments at the annual conference of the World Horse Welfare charity last year, where she said a debate was needed on the horsemeat trade in this country.
Discussing how the recession left many horse-owners abandoning them after no longer being unable to afford them, the royal suggested that selling them on for meat would add value to them.
"I think that it's something that is worth looking at," she told the programme.
She added that, in previous times, horses were usually kept as working animals and so were more indispensable.
Asked if she has ever eaten horsemeat, she replied " Oh certainly", adding that it tasted "very good actually".
Mr Jones also criticised her comments on horsemeat, describing them as " simply wrong".
He said: "Horse neglect and abandonment continue to be an issue throughout Europe and in countries exporting horse meat to the EU, even though sending a horse to slaughter is already an option.
"The documented evidence of horse suffering during transport to and at slaughterhouses in Europe and beyond is irrefutable.
"Promoting horsemeat could actually encourage neglect as owners are more likely to withhold certain medical treatments knowing that many veterinary drugs are banned for human consumption.
"Tackling horse neglect is a laudable cause but not one that will be benefited by consigning horses to be killed for food."
Environment Secretary Owen Paterson noted last year that gassing badgers was being considered but would only be used if proven to be safe, humane and effective.
Rosie Woodroffe, from the Zoological Society of London, told the BBC: "It's tempting to think it might be easier to kill badgers when they're basically a sitting target underground but it turns out from reports done in the 70s that it's not just that straightforward.
"Setts would be gassed and then opened up again by the badgers again and again and again, and the problem seemed to be that badger setts are built to hold warm air in and keep cold draughts out, so it's very difficult to achieve lethal concentrations of gas and some lethal concentrations of gas are inhumane."
In a statement to the House of Commons yesterday, Mr Paterson added measures to tackle TB in livestock in England, cattle movement controls and a grant-funded scheme for badger vaccination projects in areas around the edge of disease hotspots.
The princess's comments were also condemned by Green Party animals spokeswoman Caroline Allen.
Ms Allen, who is a working vet, said: "It is very sad that a high-profile figure such as Princess Anne has chosen to weigh in to the badger debate showing even less awareness and even more ignorance on the issue than we have come to expect from Secretary of State Owen Paterson.
"Research clearly shows that gassing badgers is even more inhumane than shooting and the Independent Panel Reports has shown that was bad enough.
"Defra has clearly stated that gassing with cyanide should never again be considered and there are no alternate gases available without similar unacceptable effects."