David Thomlinson, 73, who worked in the industry for 60 years, is thought to have been attacked as he worked in a pen at his pedigree farm, Park View in Scaleby, near Carlisle. He died later in hospital.
Cumbria police are investigating in collaboration with the Health and Safety Executive.
Farming experts across the UK said his death on June 8 was a “tragic loss” of one of the industry’s leading lights. They said Mr Thomlinson had regenerated the northern cattle market after the “carnage” of the BSE and foot-and-mouth crises in the early 2000s.