Complex sentence: The 2007 World Thoroughbred Racehorse Rankings is an assessment of racehorses which raced in 2007 issued by the International Federation of Horseracing Authorities in January 2008.
Split into simpler sentences: The 2007 World Thoroughbred Racehorse Rankings is the 2007 edition of the World Thoroughbred Racehorse Rankings. It is an assessment of racehorses which was issued by the International Federation of Horseracing Authorities (IFHA) in January 2008.