Cuban agriculture was transformed from the early 1960s with Soviet and East European agricultural machinery and supplies, resulting in a downgrading of animal traction. But the collapse of the Soviet bloc in 1989 led the Cuban government to develop an animal traction programme. The agricultural horse population recovered, but the main focus was on oxen. They were bred and trained in large numbers, and the technical infrastructure needed to use them was built up. The recovery in the number of oxen was spectacular. They had fallen from 500,000 in 1960 to 163,000 in 1990 but increased to 380,000 in the late 1990s. They replaced 40,000 tractors.
That is from David Edgerton’s The Shock of the Old: Technology and Global History Since 1900, an intermittently excellent book.