They have semen on Western Dynamo and he was 60's, but they were having success with freezing in the 40's. i would think someone somewhere has some of those bulls from 50's and on. they say ABS has a pretty extensive collection.
commercial production started then, but I heard that some of the earliest attempts were made in the late 1800s in europe. Sounds goofy I know but thats what i've heard
Definately the 40's because thats when CRI (Genex) started successfully freezing semen. I would think, though, that it started much earlier than the 40's.
An article on "history of AI" said that the semen straw was designed in the 20's. Dogs were the first to be AI's then horses then cattle. The actually freezing started successfullly in the late 30's early 40's. Many mixtures were used to preserve the sperm as well as protect it from cold shock. AI does go back to 1820 and was played with up til modern day.