Complex sentence: Crossing Bay Abi on these imported Polish mares proved particularly successful for Varian, and there are now nine generations of horses at the Varian ranch descended from these foundation mares, and five successive generations of ranch stallions descended from Bay Abi.
Split into simpler sentences: Crossing Bay Abi on these imported Polish mares proved particularly successful for Varian. The Varian ranch now has bred nine generations of horses descended from these foundation mares, and has stood five successive generations of stallions descended from Bay Abi.