The invention described herein provides high throughput methods and reagents for generating transgenic animals (e.g., non-human mammals) through introducing a CRISPR/Cas9 system comprising a Cas9 protein into gametes or preimplantation stage embryos (e.g., one-cell embryos or zygotes) via multiple cycles (e.g., 4- 10 cycles) of electroporation, leading to genetically inheritable modification to the genome of the animal.