HOUSTON, May 4 (Reuters) - Plains All American Pipeline LP on Wednesday raised its profit forecast for the year by 3.4% as the company expects higher volumes from the top U.S. shale field.

The pipeline operator increased a full-year adjusted earnings guidance by $75 million to about $2.28 billion and forecast Permian gathering volume to grow around 280,000 barrels per day in 2022. (Reporting by Arathy Somasekhar in Houston; editing by Diane Craft)