It's a Grand Old Nag

Plot
Charlie Horse is brought to Hollywood by a powerful producer. He thinks he's going to be a star, but he ends up as the stunt double for the leading man. After getting abused a couple times, the star has a love scene with his leading lady, Hay-dy La Mare, and accidentally starts a fire. Charlie rescues the lady and they live together happily ever after.

Summary
Hayseed horse Charlie is discovered down on the farm by your typical beret-wearing Hollywood director (Mister Retake, driving what looks like a 50-foot-long limousine, but which is actually a cardboard cutout of the same).

Charlie is whisked off to Tinseltown where it turns out he'll serve as stunt double for stallion superstar Clark Stable. Charlie falls for silky-tailed, femme fatale filly Hay-dy LaMare, who, of course, won't give him the time of day. However, when the set catches fire and Clark turns chicken, Charlie saves the day and wins Hay-dy's horsey heart.

The last shot in the cartoon shows dozens of li'l Charlies parachuting down from the bundle the stork is bringing.