Methods, uses, and compositions for manipulating genomic DNA. Some of the embodiments of the invention provide for making a founder animal that is completely free of all unplanned genetic modifications. Some embodiments are directed to removing genetic faults in established breeds without making other alterations to the genome. Other embodiments are directed to particular tools or processes such as TALENs or CRISPR with a preferred truncation. One embodiment involves introducing a targeted targeting endonuclease system and a HDR template into a cell (optionally with a mismatch in the binding of the targeting endonuclease and the targeted site). Another embodiment includes processes of making a genetically modified livestock animal comprising a genome that comprises inactivation of a neuroendocrine gene selective for sexual maturation, with the inactivation of the gene preventing the animal from becoming sexually mature. One embodiment includes compositions and methods for making livestock with a polled allele, including migrating a polled allele into a bovine species without changing other genes or chromosomal portions.
