Being a former sheep-farmer, I shall slip you an evil inside information

Artificial insemination is indeed used in order to get a good breed without moving the rams between various parts of the country. A straw is ... smaller, lighter and you can have a lot of them.
But you have to know when the ewes are hot. They do not show that so easily, - except to the ram. A typical ram will be able to handle about 40 sheep with approx 90% success. There is but one intercourse, and then it is all over, - just a few seconds.
So, to find out which ewes are hot (a typical average of 1/14th of the group, since they are hot for a day or so, and their cycle is 14 days), one takes a ram for a walk around the heard with a rope tied on the horns. Leave the ram to his look-around, and when an ewe approaches and waggles the tail, that is one to catch. Make an ID on the ewe, tie up the ram, catch the ewe and put into another box, and repeat untill the search is complete.
Poor ram gets nothing that day. However, he'll normally have the rest, since just a few ewes with the super-stock will produce a good stocked ram for the next year

Evil isn't it.....