Lady Russell said: "It is lovely to see so many people from all over the world gathered here. Ballindalloch is one of the few castles that has been lived in consistently and I was brought up with the Aberdeen Angus grazing peacefully here."
Charles is a long-time Angus enthusiast. He is patron of the Aberdeen-Angus Cattle Society and breeds Angus at Highgrove, Gloucestershire.
Paulo Costa, secretary of the Azores Aberdeen Angus Breeders Association, said: "This is a very special day for breeders. We started breeding Aberdeen Angus in 2007 and have developed a very strong relationship with the Aberdeen-Angus Club. It is a special moment to have come to the home of it."
The royal visitor, wearing the Gordon Highlanders tartan, spent time meeting and chatting to representatives from breeders' groups. He was then guided by farm manager David Johnstone to a marquee, where paintings and silverware illustrating the history and success of the Aberdeen Angus breed were on show.
Charles chuckled as he walked on into a field, welcomed by a sign on the gate stating: "Admission is free. The bull will charge you later."