Well it is unlikely (due to the sexual aspects) that we would get a scientific study on this.

But we have seen the use of bull sperm as a hair treatment by expensive salons in Europe. Some of the superstar long hair ladies of the internet will admit to it as their "special secret" but do not want to mention this as a public item for sure.

I would say as women get older, into middle age and hormonal changes, the value of this treatment increases, especially if they want to maintain quality at a very long length.