UKIP activist John Rees-Evans, who has become the eighth person to declare in his party's leadership contest, has previously accused a "homosexual donkey" of raping his horse.
The former parliamentary candidate made the comments in 2014 while outside his campaign office in a discussion that was filmed by anti-UKIP protesters.
The protesters angrily quoted one UKIP activist as saying "some homosexuals prefer sex with animals".
In response Rees-Evans said: "Actually I’ve witnessed that," and went on to describe how "a homosexual donkey" raped his horse.
"I was personally quite amazed, I’ve got a horse, it was in the fields, and a donkey came up – because my horse is a stallion, right – a donkey came up which is male, and I’m afraid tried to rape my horse,” he said.
Making a biting gesture, he said: "And my horse bit the side of the neck of the donkey." He went on saying: "I had to go and give my horse a slap," while making a slapping gesture, "to protect the donkey".
Rees-Evans, who is a competitive speed pistol shooter, announced his candidature on BBC's Daily Politics, describing himself as an "entrepreneur with a background in mountaineering" and dismissed the homosexual donkey comment as "playful banter".
He was then immediately forced to dispute a Vice News article that suggested he insisted on taking his Glock handgun into a Bulgarian branch of Ikea in case there was terrorist attack while he was inside the store.
Rees-Evans said the Vice article was written for an audience that liked "exaggerated journalism" and insisted, contrary to other claims in it, that he was not building "a secure compound in case of a global meltdown featuring a church, leisure complex, a firing range, and a watchtower that will double as a diving platform".
He also insisted those stories were irrelevant to his UKIP leadership bid: "With all due respect, I believe that people are actually interested in why I'm standing."
Eight candidates have now declared their intention to run in the UKIP leadership election, which follows the decision of Diane James to step down after just 18 days as leader. Candidates have to collect 75 signatures and pay a £5,000 deposit by 31 October if they want to stand. A winner will be declared a month later.
Rees-Evans warned that UKIP is at a crossroads, with other leadership candidates scrapping among each other because they are "freedom fighters without an enemy" and soldiers have a tendency to attack each other when off-duty.
Instead, he would instil a system of direct democracy in which "the leadership doesn't have any authority to move the party" without direct consent from ordinary members.
Rees-Evans concluded by saying his chances depended on the media ignoring stories about his background and instead focusing on his policy proposals: "It all depends on whether people in the media wants to listen to my ideas or want to trivialise it."