here's a link of biopsied embryo's at cal poly using PCR with pregnancy rates
http://72.14.253.104/search?q=cache:dUH9DGlIXAMJ:ari.calpoly.edu/images/45300%2520Plummer%2520Beckett%2520Final.doc+cal+poly+testing+embryo%27s&hl=en&ct=clnk&cd=2&gl=us&client=firefox-a
here is another link of grants received from cal poly including some that are relevant to topic
http://ari.calpoly.edu/projects.htm look at first topic Application of Multiple Marker, Pre-implantation Genetic Testing of Bovine Embryos
i don't know the relative success of these programs, but in theory, it should be doable. one would have to determine the number of cells stage to do this at. the comment about the whole genome amplification is interesting as a way to minimize tissue harvest. DL, is there any tissue associated with an embryo that isn't a part of the embryo, but contains the DNA that could be used for this? also, is there any tissue in a semen sample, not the semen, but a sloughed vas deferens cell say, that could be used as a source for cloning, say cunia or some other bull?
we routinely use as little as 2.5 ng of dna to do pcr, and others routinely do this using what's called rolling circle amplification to amplify dna from low concentration samples before performing a pcr reaction. DL probably knows this, but at some stage, all embryo's are female, then they get the signal to be a male. perhaps this could be detected routinely and cheaply as an alternative, or maybe it's just too far along in the development stage to be routinely implanted again. don't know that.