Farm horses were pretty important from the time our relatives arrived in the United States right up to WWII. Like typical competitors, farmers were known by their teams--how big they were, how much they could pull, and eventually, how pure-bred they were (the teams, not the farmers). We started seeing "stallion service" ads in the Pierz Journal in 1910--a subject that was a bit earthy for tender sensibilities, but words like "service", "standing" and "a single leap" were euphemistic enough. You got the picture.
Watching was probably a popular (and randy) passtime, too. Ahem.