While it’s true that hearing this would broaden your horse’s awareness of the world outside your barn and put their own suffering into perspective, the ensuing air of existential grief would make it difficult for your horse to care about the menial labor you require of them. They will only want to sit and mourn the unnamed horse lost to time, which would make for a very unproductive day at the barn.
https://www.pastemagazine.com/music/best-songs/25-songs-about-horses-ranked-by-how-much-i-think-you-should-play-them-for-your-horse