We have had very good results with some donors since we started deep breeding. This is not something for an amateur to do as a straw of semen is deposited after the horn of the uterus is pulled over the pipette until the end of the pipette is near the far end of the horn and the semen is then deposited. I won't try it myself, but my ET vets do it and we have some donors who have doubled the number of fertilized embryos we get. We have one donor in particular who never had more than a maximum of 8 grade 1 embryos but since we started to deep breed, she has produced between 15 to 24 grade 1 embryos. Like I said, it is something for an very experienced tech to do as it is possible to damage the wall of the uterus, if you don't know what you are doing. We have seen much better results in almost every donor we have done this on, but it takes 4 straws of semen rather than the regular one or two as you deposit a straw in each horn in each breeding. Seems to be working for us anyways