several researchers are testing to see if they can tease off some cells from an embryo, do some DNA tests etc. from what i've seen, which ain't much, they are just proving the concept with some of the carcass genes.
if one were to test for PHA and TH, they would have to license the test through Dr. Beever's lab. probably the key, would be to do the test in 1/2, which can be done in the field with current technology, and get the egg mass at the 60 odd cell stage (cowboy), and throw it back in there.
cowboy could speak up, but you could even get to the point of testing embryo's for being double carriers, keep separating them and basically have an infinite supply of cell lines. one could simply clone the 3 or 4 best steers, generate 1 billion eggs, and sell them and not even bother with trying to find out which bull nicks with which cow. that way, everyone could then battle over which donor cow or recip cow is best to raise the best steer. feeding, health, clipping etc, and other care practices would be even more important as the steer war escalates. at some point, since all the steers are the same, fit jobs could become even more "important". it would be pretty funny, if all steers at a show were clones, and the show was a slick show. then there would be a whole new set of rules. did the kid clone the steer themselves, was the right number of cells used, did they get a hired gun embryologist to do the dirty work, and which parents did all the work for them..............
cost, hmmm, a pcr test from a lab varies from around $8 bucks if you send them pre isolated DNA to around $30 for a single test and less per test the more tests you do from that original extraction, ie 11 tests with the bovigen panel for multiplex (multiple reactions in the same tube) or other methods with a single reaction and multiple fragments.
i think semen is sexed by centrifugation as the female sperm weigh more, talk about discrimination, and they sort to different levels in a tube. maybe it's changed with better techniques.
i don't think at this stage you can test a single sperm cell without destroying it unless you had raquel welch doing it with a fantastic voyage.