Although the clovers have more than grass due to be Legumes, as long as you let the grass come to the cows -- in other words they are slowly acclimated to it, I don't see the same effects that way.
By changing rapodly form Fro lot to Green grass, it sets off the whole process. For those of you who are ranchers and have to feed dry all winter, then you go to grass all at once, you wil notice those thinner, ratty looking cows with hair patches missng etc. These cows hot the green and within a week it seems they are all coming into heat. Nature is at work for sure!
I wouldhave never noticed this phenom had itnot been for me doing the very same thing once. I had put in about a dozen Holstien embryos on a contract sale (Yes, I did owen some dry, older, VERY good Holsteins many years ago). Of the 12, there were 9 very solid non-returns to heat on the hfrs we used. I was confident they had taken the embryos, and at about 25-30 days, I simply let them out of the dry lot, walked them 100 feet to a 1 acre irrigated paddock by the house. I was really happy as these were sold for BIG money. WELL?? within 7 days I had lost all but 2 of the 9, and non were normal heat cycle dates.
I was furious when I found out thru research what I had just done to myself. Now -- I make darn sure that if we transfer on dry lots conditions and the recips were never acclimated to grass first, I wait until they are at least 45 days pregnant before I move them out. The embryo is basicly a free floating entity up until about day 37 when it attaches to a cotiledon. After that, the risk of envrionmental disruption is much less. Ihaven't been sorry since!
Food for thought folks, let the grass come to the cows as you continue to feed, they will gradually eat less dry and more green. It works!
Best of luck to all --