Sayyiduna Urwah bin Abi al-Ja'd (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "Goodness has been tied to the forelocks of horses until the Day of Resurrection, and the spoils too have been placed in their forelocks." This indicates that the spoils have been linked to the genus of horses, so hybrid horses too are in origin of the horse breed.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 17963