Which specific breeds did farmers introduce that diluted the Welsh Black genetics during the 20th century decline?

Answer

Herefords or continental European breeds

The evolutionary path of the Welsh Black faced a sharp negative turn in the 20th century due to the industrialization of agriculture and a shift toward specialization. Farmers began introducing continental European breeds or specific English breeds, such as Herefords, with the goal of maximizing either pure beef conformation or milk yield rapidly. This crossbreeding activity inevitably diluted the time-tested and specific genetics inherent to the native Welsh animal population, leading to a sharp reduction in purebred numbers.

Which specific breeds did farmers introduce that diluted the Welsh Black genetics during the 20th century decline?
evolutioncattlebreedbovineWelsh