I have found that a good mineral is essential. I don't think it is real important as to what you feed, providing it is good enough to flush the recips. What I have found is really important is that the recips go back on the same ration after being implanted as they were on before. So if your recips are on grass prior to implantation, put them back on grass afterwards, and if they were dry lotted prior to implanting, put them back in the dry lot on the same ration afterwards. I have found my pregnancy rates have increased substantially since I started doing this. I used to dry lot my recips prior to implanting simply because it was handy for me, and once they were implanted I would kick them out on pasture. I really had a mixed bag of results. Once I stayed with the same program, my preg rates improved.